1 Week 11 TCP Congestion Control. 2 Principles of Congestion Control Congestion: r informally:...

1

Week 11TCP Congestion Control

2

Principles of Congestion Control

Congestion informally ldquotoo many sources sending too

much data too fast for network to handlerdquo

different from flow control

manifestations

lost packets (buffer overflow at routers)

long delays (queueing in router buffers)

a top-10 problem

3

Causescosts of congestion scenario 1

two senders two receivers

one router infinite buffers

no retransmission

large delays when congested

maximum achievable throughput

unlimited shared output link buffers

Host Ain original data

Host B

out

4


one router finite buffers

sender retransmission of lost packet

finite shared output link buffers

Host A in original data

Host B

out

in original data plus retransmitted data

5

Causescosts of congestion scenario 2 always (goodput)

ldquoperfectrdquo retransmission only when loss

retransmission of delayed (not lost) packet makes

larger (than perfect case) for same

in

out

=

in

out

gt

in

out

ldquocostsrdquo of congestion

more work (retrans) for given ldquogoodputrdquo

unneeded retransmissions link carries multiple copies of pkt

R2

R2in

ou

t

b

R2

R2in

ou

t

a

R2

R2in

ou

t

c

R4

R3

6

Causescosts of congestion scenario 3 four senders

multihop paths

timeoutretransmit

inQ what happens as

and increase in



Host B

out


7

Example

What happens when each demand peaks at unity rateThroughput = 152 (How) twice the unity rate T = 107

8

Max-min fair allocation

Given a network and a set of sessions we would like to find a maximal flow that it is fair

We will see different definitions for max-min fairness and will learn a flow control algorithm

The tutorial will give understanding what is max-min fairness

9

How define fairness

Any session is entitled to as much network use as is any other

Allocating the same share to all

10

Max-Min Flow Control Rule

The rule is maximizing the network use allocated to the sessions with the minimum allocation

An alternative definition is to maximize the allocation of each session i under constraint that an increase in irsquos allocation doesnrsquot cause a decrease in some other session allocation with the same or smaller rate than i

11

Example

Maximal fair flow division will be to give for the sessions 012 a flow rate of 13 and for the session 3 a flow rate of 23

C=1 C=1

Session 1

Session 2 Session 3

Session 0

12

Notation

G=(NA) - Directed network graph (N is set of vertexes and A is set of edges)

Ca ndash the capacity of a link a

Fa ndash the flow on a link a

P ndash a set of the sessions rp ndash the rate of a session p

We assume a fixed single-path routing method

13

Definitions

We have following constraints on the vector r= rp | p Є P

A vector r satisfying these constraints is said to be feasible

alink crossing

p sessions allpa r F

allfor

allfor 0

AaCF

Ppr

aa

p

14

Definitions

A vector of rates r is said to be max-min

fair if is a feasible and for each p Є P rp

can not be increased while maintaining

feasibility without decreasing rprsquo for

some session prsquo for which rprsquo le rp

We want to find a rate vector that is max-min fair

15

Bottleneck Link for a Session

Given some feasible flow r we say that a is a bottleneck link with respect to r for a session p crossing a if Fa = Ca and rp ge rprsquo for all sessions prsquo crossing link a

1

2 3

4

5

213313513

12341

a

b

c

d

All link capacity is 1 Bottlenecks for 12345 respectively are caadaNote c is not a bottleneck for 5 and b is not a bottleneck for 1

16

Max-Min Fairness Definition Using Bottleneck Theorem A feasible rate vector r is

max-min fair if and only if each session has a bottleneck link with respect to r

17

Algorithm for Computing Max-Min Fair Rate Vectors

The idea of the algorithm Bring all the sessions to the state that they

have a bottleneck link and then according to theorem it will be the maximal fair flow

We start with all-zero rate vector and to increase rates on all paths together until Fa = Ca for one or more links a

At this point each session using a saturated link has the same rate as every other session using this link Thus these saturated links serve as bottleneck links for all sessions using them

18

Algorithm for Computing Max-Min Fair Rate Vectors At the next step all sessions not using the

saturated links are incremented equally in rate until one or more new links become saturated

Note that the sessions using the previously saturated links might also be using these newly saturated links (at a lower rate)

The algorithm continues from step to step always equally incrementing all sessions not passing through any saturated link until all session pass through at least one such link

19

Algorithm for Computing Max-Min Fair Rate VectorsInit k=1 Fa

0=0 rp0=0 P1=P and A1=A

1 For all aA nak= num of sessions pPk

crossing link a2 Δr=minaA

k(Ca-Fak-1)na

k (find inc size)3 For all p Pk rp

k=rpk-1+ Δr (increment)

for other p rpk=rp

k-1

4 Fak=Σp crossing arp

k (Update flow)5 Ak+1= The set of unsaturated links6 Pk+1=all prsquos such that p cross only links in

Ak+1

7 k=k+18 If Pk is empty then stop else goto 1

Rami Cohen
שומר על פיסיביליות ועל הגינות

20

Example of Algorithm Running

Step 1 All sessions get a rate of 13 because of a and the link a is saturated

Step 2 Sessions 1 and 4 get an additional rate increment of 13 for a total of 23 Link c is saturated now

Step 3 Session 4 gets an additional rate increment of 13 for a total of 1 Link d is saturated

End

1

2 3

4

5

213313513

12341

a

b

c

d

All link capacity is 1

21

Example revisited

Max-min fair vector if Tij = infin r = (frac12 frac12 frac12 frac12 ) T = 2 gt 152

What if the demands T13

and T31 = frac14

T24 = frac12 T42 = infin r = (frac14 frac12 frac14 frac34)

22


Another ldquocostrdquo of congestion

when packet dropped any ldquoupstream transmission capacity used for that packet was wasted

Host A

Host B

o

u

t

23

Approaches towards congestion control

End-end congestion control

no explicit feedback from network

congestion inferred from end-system observed loss delay

approach taken by TCP

Network-assisted congestion control

routers provide feedback to end systems

single bit indicating congestion (SNA DECbit TCPIP ECN ATM)

explicit rate sender should send at

Two broad approaches towards congestion control

24

Case study ATM ABR congestion control

ABR available bit rate ldquoelastic servicerdquo

if senderrsquos path ldquounderloadedrdquo

sender should use available bandwidth

if senderrsquos path congested

sender throttled to minimum guaranteed rate

RM (resource management) cells

sent by sender interspersed with data cells

bits in RM cell set by switches (ldquonetwork-assistedrdquo)

NI bit no increase in rate (mild congestion)

CI bit congestion indication

RM cells returned to sender by receiver with bits intact

25


two-byte ER (explicit rate) field in RM cell congested switch may lower ER value in cell

senderrsquo send rate thus minimum supportable rate on path

EFCI bit in data cells set to 1 in congested switch if data cell preceding RM cell has EFCI set sender sets CI bit

in returned RM cell

26

TCP Congestion Control

end-end control (no network assistance)

sender limits transmission LastByteSent-LastByteAcked

CongWin

Roughly

CongWin is dynamic function of perceived network congestion

How does sender perceive congestion

loss event = timeout or 3 duplicate acks

TCP sender reduces rate (CongWin) after loss event

three mechanisms AIMD

slow start

conservative after timeout events

rate = CongWin

RTT Bytessec

27

TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow

multiplicative decrease cut CongWin in half after loss event

additive increase increase CongWin by 1 MSS every RTT in the absence of loss events probing

Long-lived TCP connection

28

Additive Increase

increase CongWin by 1 MSS every RTT in the absence of loss events probing

cwnd += SMSSSMSScwnd () This adjustment is executed on every

incoming non-duplicate ACK Equation () provides an acceptable

approximation to the underlying principle of increasing cwnd by 1 full-sized segment per RTT

29

TCP Slow Start

When connection begins CongWin = 1 MSS Example MSS = 500

bytes amp RTT = 200 msec

initial rate = 20 kbps

available bandwidth may be gtgt MSSRTT desirable to quickly ramp

up to respectable rate

When connection begins increase rate exponentially fast until first loss event

30

TCP Slow Start (more) When connection

begins increase rate exponentially until first loss event double CongWin every

RTT

done by incrementing CongWin for every ACK received

Summary initial rate is slow but ramps up exponentially fast

Host A

one segment

RTT

Host B

time

two segments

four segments

31

Refinement After 3 dup ACKs

CongWin is cut in half Threshold is set to CongWin

window then grows linearly

But after timeout event

Threshold set to CongWin2 and

CongWin instead set to 1 MSS

window then grows exponentially

to a threshold then grows linearly

bull 3 dup ACKs indicates network capable of delivering some segmentsbull timeout before 3 dup ACKs is ldquomore alarmingrdquo

Philosophy

32

Refinement (more)Q When should the

exponential increase switch to linear

A When CongWin gets to 12 of its value before timeout

Implementation Variable Threshold

At loss event Threshold is set to 12 of CongWin just before loss event

33

Summary TCP Congestion Control

When CongWin is below Threshold sender in slow-start phase window grows exponentially

When CongWin is above Threshold sender is in congestion-avoidance phase window grows linearly

When a triple duplicate ACK occurs Threshold set to CongWin2 and CongWin set to Threshold

When timeout occurs Threshold set to CongWin2 and CongWin is set to 1 MSS

34

TCP sender congestion controlEvent State TCP Sender Action Commentary

ACK receipt for

previously unacked

data

Slow Start (SS) CongWin = CongWin + MSS

If (CongWin gt Threshold)

set state to ldquoCongestion

Avoidancerdquo

Resulting in a doubling of

CongWin every RTT

ACK receipt for

previously unacked

data

Congestion

Avoidance (CA)

CongWin = CongWin+MSS

(MSSCongWin)

Additive increase resulting in

increase of CongWin by 1 MSS

every RTT

Loss event detected

by triple duplicate

ACK

SS or CA Threshold = CongWin2

CongWin = Threshold

Set state to ldquoCongestion

Avoidancerdquo

Fast recovery implementing

multiplicative decrease CongWin

will not drop below 1 MSS

Timeout SS or CA Threshold = CongWin2

CongWin = 1 MSS

Set state to ldquoSlow Startrdquo

Enter slow start

Duplicate ACK SS or CA Increment duplicate ACK count

for segment being acked

CongWin and Threshold not

changed

35

TCP Futures

Example 1500 byte segments 100ms RTT want 10 Gbps throughput

Requires window size W = 83333 in-flight segments

Throughput in terms of loss rate

p = 210-10

New versions of TCP for high-speed needed

pRTT

MSS221

36

Macroscopic TCP model

Deterministic packet losses

1p packets transmitted in a cycle

losssuccess

37

TCP Model Contd

Equate the trapozeid area 38 W2 under to 1p

22123 C

38

Fairness goal if K TCP sessions share same bottleneck link of bandwidth R each should have average rate of RK

TCP connection 1

bottleneckrouter

capacity R

TCP connection 2

TCP Fairness

39

Why is TCP fair

Two competing sessions Additive increase gives slope of 1 as throughout increases

multiplicative decrease decreases throughput proportionally

R

R

equal bandwidth share

Connection 1 throughputConnect

ion 2

th

roughput

congestion avoidance additive increaseloss decrease window by factor of 2


40

Fairness (more)

Fairness and UDP

Multimedia apps often do not use TCP do not want rate

throttled by congestion control

Instead use UDP pump audiovideo at

constant rate tolerate packet loss

Research area TCP friendly DCCP

Fairness and parallel TCP connections

nothing prevents app from opening parallel cnctions between 2 hosts

Web browsers do this

Example link of rate R supporting 9 cnctions new app asks for 1 TCP gets

rate R10

new app asks for 10 TCPs gets R2

41

Queuing Disciplines

Each router must implement some queuing discipline

Queuing allocates both bandwidth and buffer space Bandwidth which packet to serve (transmit)

next

Buffer space which packet to drop next (when required)

Queuing also affects latency

42

Typical Internet Queuing FIFO + drop-tail

Simplest choice

Used widely in the Internet

FIFO (first-in-first-out) Implies single class of traffic

Drop-tail Arriving packets get dropped when queue is full regardless

of flow or importance

Important distinction FIFO scheduling discipline

Drop-tail drop policy

43

FIFO + Drop-tail Problems

Leaves responsibility of congestion control completely to the edges (eg TCP)

Does not separate between different flows

No policing send more packets get more service

Synchronization end hosts react to same events

44


Full queues Routers are forced to have have large queues

to maintain high utilizations

TCP detects congestion from lossbull Forces network to have long standing queues in

steady-state

Lock-out problem Drop-tail routers treat bursty traffic poorly

Traffic gets synchronized easily allows a few flows to monopolize the queue space

45

Active Queue Management

Design active router queue management to aid congestion control

Why Router has unified view of queuing behavior

Routers see actual queue occupancy (distinguish queue delay and propagation delay)

Routers can decide on transient congestion based on workload

46

Design Objectives

Keep throughput high and delay low High power (throughputdelay)

Accommodate bursts

Queue size should reflect ability to accept bursts rather than steady-state queuing

Improve TCP performance with minimal hardware changes

47

Lock-out Problem

Random drop Packet arriving when queue is full causes

some random packet to be dropped

Drop front On full queue drop packet at head of queue

Random drop and drop front solve the lock-out problem but not the full-queues problem

48

Full Queues Problem

Drop packets before queue becomes full (early drop)

Intuition notify senders of incipient congestionExample early random drop (ERD)

bull If qlen gt drop level drop each new packet with fixed probability p

bull Does not control misbehaving users

49

Random Early Detection (RED) Detect incipient congestion

Assume hosts respond to lost packets

Avoid window synchronization Randomly mark packets

Avoid bias against bursty traffic

50

RED Algorithm

Maintain running average of queue length

If avg lt minth do nothing Low queuing send packets through

If avg gt maxth drop packet Protection from misbehaving sources

Else mark packet in a manner proportional to queue length Notify sources of incipient congestion

51

RED OperationMin threshMax thresh

Average Queue Length

minth maxth

maxP

10

Avg queue length

P(drop)

52

Improving QOS in IP NetworksThus far ldquomaking the best of best effortrdquo

Future next generation Internet with QoS guarantees

RSVP signaling for resource reservations

Differentiated Services differential guarantees

Integrated Services firm guarantees

simple model for sharing and congestion studies

53

Principles for QOS Guarantees Example 1Mbps IP phone FTP share 15 Mbps

link bursts of FTP can congest router cause audio loss

want to give priority to audio over FTP

packet marking needed for router to distinguish between different classes and new router policy to treat packets accordingly

Principle 1

54

Principles for QOS Guarantees (more) what if applications misbehave (audio sends higher than

declared rate) policing force source adherence to bandwidth allocations

marking and policing at network edge similar to ATM UNI (User Network Interface)

provide protection (isolation) for one class from othersPrinciple 2

55

Principles for QOS Guarantees (more) Allocating fixed (non-sharable) bandwidth to flow

inefficient use of bandwidth if flows doesnrsquot use its allocation

While providing isolation it is desirable to use resources as efficiently as possible

Principle 3

56

Principles for QOS Guarantees (more) Basic fact of life can not support traffic demands

beyond link capacity

Call Admission flow declares its needs network may block call (eg busy signal) if it cannot meet needs

Principle 4

57

Summary of QoS Principles

Letrsquos next look at mechanisms for achieving this hellip

58

Scheduling And Policing Mechanisms scheduling choose next packet to send on link

FIFO (first in first out) scheduling send in order of arrival to queue real-world example

discard policy if packet arrives to full queue who to discard

bull Tail drop drop arriving packet

bull priority dropremove on priority basis

bull random dropremove randomly

59

Scheduling Policies morePriority scheduling transmit highest priority

queued packet

multiple classes with different priorities class may depend on marking or other header info eg

IP sourcedest port numbers etc

60

Scheduling Policies still moreround robin scheduling

multiple classes

cyclically scan class queues serving one from each class (if available)

61

Scheduling Policies still more

Weighted Fair Queuing

generalized Round Robin

each class gets weighted amount of service in each cycle

62

Deficit Weighted Round Robin (DWRR) DWRR addresses the limitations of the WRR

model by accurately supporting the weighted fair distribution of bandwidth when servicing queues that contain variable-length packets

DWRR addresses the limitations of the WFQ model by defining a scheduling discipline that has lower computational complexity and that can be implemented in hardware This allows DWRR to support the arbitration of output port bandwidth on high-speed interfaces in both the core and at the edges of the network

63

DRR

In DWRR queuing each queue is configured with a number of parameters A weight that defines the percentage of the output

port bandwidth allocated to the queue A DeficitCounter that specifies the total number of

bytes that the queue is permitted to transmit each time that it is visited by the scheduler The DeficitCounter allows a queue that was not permitted to transmit in the previous round because the packet at the head of the queue was larger than the value of the DeficitCounter to save transmission ldquocreditsrdquo and use them during the next service round

64

DWRR In the classic DWRR algorithm the scheduler

visits each non-empty queue and determines the number of bytes in the packet at the head of the queue

The variable DeficitCounter isincremented by the value quantum If the size of the packet at the head of the queue is greater than the variable DeficitCounter then the scheduler moves on to service the next queue

If the size of the packet at the head of the queue is less than or equal to the variable DeficitCounter then the variable DeficitCounter is reduced by the number of bytes in the packet and the packet is transmitted on the output port

65

DWRR A quantum of service that is proportional to the

weight of the queue and is expressed in terms of bytes The DeficitCounter for a queue is incremented by the quantum each time that the queue is visited by the scheduler

The scheduler continues to dequeue packets and decrement the variable DeficitCounter by the size of the transmitted packet until either the size of the packet at the head of the queue is greater than the variable DeficitCounter or the queue is empty

If the queue is empty the value of DeficitCounter is set to zero

66

DWRR Example

600400300

400 400300

600300400

Queue 1 50 BW quantum[1] =1000



Modified Deficit Round Robin gives priority to one say VoIP class

67

Policing MechanismsGoal limit traffic to not exceed declared parameters

Three common-used criteria

(Long term) Average Rate how many pkts can be sent per unit time (in the long run) crucial question what is the interval length 100 packets per sec or 6000 packets per min

have same average

Peak Rate eg 6000 pkts per min (ppm) avg 1500 ppm peak rate

(Max) Burst Size max number of pkts sent consecutively (with no intervening idle)

68

Policing Mechanisms

Token Bucket limit input to specified Burst Size and

Average Rate

bucket can hold b tokens

tokens generated at rate r tokensec unless bucket full

over interval of length t number of packets admitted less than or equal to (r t + b)

69

Policing Mechanisms (more)

token bucket WFQ combine to provide guaranteed upper bound on delay ie QoS guarantee

WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic

Week 11 TCP Congestion Control




Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14


Max-Min Fairness Definition Using Bottleneck


Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start

TCP Slow Start (more)

Refinement

Refinement (more)


TCP sender congestion control

TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines

Typical Internet Queuing


Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem

Random Early Detection (RED)

RED Algorithm

RED Operation

Improving QOS in IP Networks

Principles for QOS Guarantees

Principles for QOS Guarantees (more)

Slide 55

Slide 56


Scheduling And Policing Mechanisms

Scheduling Policies more


Slide 61

Deficit Weighted Round Robin (DWRR)

DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


2


Congestion informally ldquotoo many sources sending too

much data too fast for network to handlerdquo

different from flow control

manifestations

lost packets (buffer overflow at routers)

long delays (queueing in router buffers)

a top-10 problem

3




no retransmission





Host B

out

4






Host B

out


5





in

out

=

in

out

gt

in

out




R2

R2in

ou

t

b

R2

R2in

ou

t

a

R2

R2in

ou

t

c

R4

R3

6


multihop paths

timeoutretransmit

inQ what happens as

and increase in



Host B

out


7

Example


8





9

How define fairness



10




11

Example


C=1 C=1

Session 1

Session 2 Session 3

Session 0

12

Notation






13

Definitions



alink crossing


allfor

allfor 0

AaCF

Ppr

aa

p

14

Definitions







15



1

2 3

4

5

213313513

12341

a

b

c

d


16



17






18





19


0=0 rp0=0 P1=P and A1=A



k(Ca-Fak-1)na



for other p rpk=rp

k-1



Ak+1


Rami Cohen

20





End

1

2 3

4

5

213313513

12341

a

b

c

d


21

Example revisited



and T31 = frac14


22




Host A

Host B

o

u

t

23











24













25





in returned RM cell

26




CongWin

Roughly






slow start


rate = CongWin

RTT Bytessec

27

TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow




28

Additive Increase





29

TCP Slow Start







30



RTT



Host A

one segment

RTT

Host B

time

two segments

four segments

31










Philosophy

32






33






34


ACK receipt for

previously unacked

data




Avoidancerdquo


CongWin every RTT

ACK receipt for

previously unacked

data

Congestion

Avoidance (CA)


(MSSCongWin)



every RTT

Loss event detected

by triple duplicate

ACK


CongWin = Threshold


Avoidancerdquo





CongWin = 1 MSS


Enter slow start




changed

35

TCP Futures




p = 210-10


pRTT

MSS221

36




losssuccess

37

TCP Model Contd


22123 C

38


TCP connection 1

bottleneckrouter

capacity R

TCP connection 2

TCP Fairness

39

Why is TCP fair



R

R



ion 2

th

roughput



40

Fairness (more)

Fairness and UDP










rate R10


41

Queuing Disciplines



next



42


Simplest choice







43






44





steady-state



45






46

Design Objectives


Accommodate bursts



47

Lock-out Problem





48

Full Queues Problem





49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


3




no retransmission





Host B

out

4






Host B

out


5





in

out

=

in

out

gt

in

out




R2

R2in

ou

t

b

R2

R2in

ou

t

a

R2

R2in

ou

t

c

R4

R3

6


multihop paths

timeoutretransmit

inQ what happens as

and increase in



Host B

out


7

Example


8





9

How define fairness



10




11

Example


C=1 C=1

Session 1

Session 2 Session 3

Session 0

12

Notation






13

Definitions



alink crossing


allfor

allfor 0

AaCF

Ppr

aa

p

14

Definitions







15



1

2 3

4

5

213313513

12341

a

b

c

d


16



17






18





19


0=0 rp0=0 P1=P and A1=A



k(Ca-Fak-1)na



for other p rpk=rp

k-1



Ak+1


Rami Cohen

20





End

1

2 3

4

5

213313513

12341

a

b

c

d


21

Example revisited



and T31 = frac14


22




Host A

Host B

o

u

t

23











24













25





in returned RM cell

26




CongWin

Roughly






slow start


rate = CongWin

RTT Bytessec

27

TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow




28

Additive Increase





29

TCP Slow Start







30



RTT



Host A

one segment

RTT

Host B

time

two segments

four segments

31










Philosophy

32






33






34


ACK receipt for

previously unacked

data




Avoidancerdquo


CongWin every RTT

ACK receipt for

previously unacked

data

Congestion

Avoidance (CA)


(MSSCongWin)



every RTT

Loss event detected

by triple duplicate

ACK


CongWin = Threshold


Avoidancerdquo





CongWin = 1 MSS


Enter slow start




changed

35

TCP Futures




p = 210-10


pRTT

MSS221

36




losssuccess

37

TCP Model Contd


22123 C

38


TCP connection 1

bottleneckrouter

capacity R

TCP connection 2

TCP Fairness

39

Why is TCP fair



R

R



ion 2

th

roughput



40

Fairness (more)

Fairness and UDP










rate R10


41

Queuing Disciplines



next



42


Simplest choice







43






44





steady-state



45






46

Design Objectives


Accommodate bursts



47

Lock-out Problem





48

Full Queues Problem





49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


4






Host B

out


5





in

out

=

in

out

gt

in

out




R2

R2in

ou

t

b

R2

R2in

ou

t

a

R2

R2in

ou

t

c

R4

R3

6


multihop paths

timeoutretransmit

inQ what happens as

and increase in



Host B

out


7

Example


8





9

How define fairness



10




11

Example


C=1 C=1

Session 1

Session 2 Session 3

Session 0

12

Notation






13

Definitions



alink crossing


allfor

allfor 0

AaCF

Ppr

aa

p

14

Definitions







15



1

2 3

4

5

213313513

12341

a

b

c

d


16



17






18





19


0=0 rp0=0 P1=P and A1=A



k(Ca-Fak-1)na



for other p rpk=rp

k-1



Ak+1


Rami Cohen

20





End

1

2 3

4

5

213313513

12341

a

b

c

d


21

Example revisited



and T31 = frac14


22




Host A

Host B

o

u

t

23











24













25





in returned RM cell

26




CongWin

Roughly






slow start


rate = CongWin

RTT Bytessec

27

TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow




28

Additive Increase





29

TCP Slow Start







30



RTT



Host A

one segment

RTT

Host B

time

two segments

four segments

31










Philosophy

32






33






34


ACK receipt for

previously unacked

data




Avoidancerdquo


CongWin every RTT

ACK receipt for

previously unacked

data

Congestion

Avoidance (CA)


(MSSCongWin)



every RTT

Loss event detected

by triple duplicate

ACK


CongWin = Threshold


Avoidancerdquo





CongWin = 1 MSS


Enter slow start




changed

35

TCP Futures




p = 210-10


pRTT

MSS221

36




losssuccess

37

TCP Model Contd


22123 C

38


TCP connection 1

bottleneckrouter

capacity R

TCP connection 2

TCP Fairness

39

Why is TCP fair



R

R



ion 2

th

roughput



40

Fairness (more)

Fairness and UDP










rate R10


41

Queuing Disciplines



next



42


Simplest choice







43






44





steady-state



45






46

Design Objectives


Accommodate bursts



47

Lock-out Problem





48

Full Queues Problem





49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


5





in

out

=

in

out

gt

in

out




R2

R2in

ou

t

b

R2

R2in

ou

t

a

R2

R2in

ou

t

c

R4

R3

6


multihop paths

timeoutretransmit

inQ what happens as

and increase in



Host B

out


7

Example


8





9

How define fairness



10




11

Example


C=1 C=1

Session 1

Session 2 Session 3

Session 0

12

Notation






13

Definitions



alink crossing


allfor

allfor 0

AaCF

Ppr

aa

p

14

Definitions







15



1

2 3

4

5

213313513

12341

a

b

c

d


16



17






18





19


0=0 rp0=0 P1=P and A1=A



k(Ca-Fak-1)na



for other p rpk=rp

k-1



Ak+1


Rami Cohen

20





End

1

2 3

4

5

213313513

12341

a

b

c

d


21

Example revisited



and T31 = frac14


22




Host A

Host B

o

u

t

23











24













25





in returned RM cell

26




CongWin

Roughly






slow start


rate = CongWin

RTT Bytessec

27

TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow




28

Additive Increase





29

TCP Slow Start







30



RTT



Host A

one segment

RTT

Host B

time

two segments

four segments

31










Philosophy

32






33






34


ACK receipt for

previously unacked

data




Avoidancerdquo


CongWin every RTT

ACK receipt for

previously unacked

data

Congestion

Avoidance (CA)


(MSSCongWin)



every RTT

Loss event detected

by triple duplicate

ACK


CongWin = Threshold


Avoidancerdquo





CongWin = 1 MSS


Enter slow start




changed

35

TCP Futures




p = 210-10


pRTT

MSS221

36




losssuccess

37

TCP Model Contd


22123 C

38


TCP connection 1

bottleneckrouter

capacity R

TCP connection 2

TCP Fairness

39

Why is TCP fair



R

R



ion 2

th

roughput



40

Fairness (more)

Fairness and UDP










rate R10


41

Queuing Disciplines



next



42


Simplest choice







43






44





steady-state



45






46

Design Objectives


Accommodate bursts



47

Lock-out Problem





48

Full Queues Problem





49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


6


multihop paths

timeoutretransmit

inQ what happens as

and increase in



Host B

out


7

Example


8





9

How define fairness



10




11

Example


C=1 C=1

Session 1

Session 2 Session 3

Session 0

12

Notation






13

Definitions



alink crossing


allfor

allfor 0

AaCF

Ppr

aa

p

14

Definitions







15



1

2 3

4

5

213313513

12341

a

b

c

d


16



17






18





19


0=0 rp0=0 P1=P and A1=A



k(Ca-Fak-1)na



for other p rpk=rp

k-1



Ak+1


Rami Cohen

20





End

1

2 3

4

5

213313513

12341

a

b

c

d


21

Example revisited



and T31 = frac14


22




Host A

Host B

o

u

t

23











24













25





in returned RM cell

26




CongWin

Roughly






slow start


rate = CongWin

RTT Bytessec

27

TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow




28

Additive Increase





29

TCP Slow Start







30



RTT



Host A

one segment

RTT

Host B

time

two segments

four segments

31










Philosophy

32






33






34


ACK receipt for

previously unacked

data




Avoidancerdquo


CongWin every RTT

ACK receipt for

previously unacked

data

Congestion

Avoidance (CA)


(MSSCongWin)



every RTT

Loss event detected

by triple duplicate

ACK


CongWin = Threshold


Avoidancerdquo





CongWin = 1 MSS


Enter slow start




changed

35

TCP Futures




p = 210-10


pRTT

MSS221

36




losssuccess

37

TCP Model Contd


22123 C

38


TCP connection 1

bottleneckrouter

capacity R

TCP connection 2

TCP Fairness

39

Why is TCP fair



R

R



ion 2

th

roughput



40

Fairness (more)

Fairness and UDP










rate R10


41

Queuing Disciplines



next



42


Simplest choice







43






44





steady-state



45






46

Design Objectives


Accommodate bursts



47

Lock-out Problem





48

Full Queues Problem





49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


7

Example


8





9

How define fairness



10




11

Example


C=1 C=1

Session 1

Session 2 Session 3

Session 0

12

Notation






13

Definitions



alink crossing


allfor

allfor 0

AaCF

Ppr

aa

p

14

Definitions







15



1

2 3

4

5

213313513

12341

a

b

c

d


16



17






18





19


0=0 rp0=0 P1=P and A1=A



k(Ca-Fak-1)na



for other p rpk=rp

k-1



Ak+1


Rami Cohen

20





End

1

2 3

4

5

213313513

12341

a

b

c

d


21

Example revisited



and T31 = frac14


22




Host A

Host B

o

u

t

23











24













25





in returned RM cell

26




CongWin

Roughly






slow start


rate = CongWin

RTT Bytessec

27

TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow




28

Additive Increase





29

TCP Slow Start







30



RTT



Host A

one segment

RTT

Host B

time

two segments

four segments

31










Philosophy

32






33






34


ACK receipt for

previously unacked

data




Avoidancerdquo


CongWin every RTT

ACK receipt for

previously unacked

data

Congestion

Avoidance (CA)


(MSSCongWin)



every RTT

Loss event detected

by triple duplicate

ACK


CongWin = Threshold


Avoidancerdquo





CongWin = 1 MSS


Enter slow start




changed

35

TCP Futures




p = 210-10


pRTT

MSS221

36




losssuccess

37

TCP Model Contd


22123 C

38


TCP connection 1

bottleneckrouter

capacity R

TCP connection 2

TCP Fairness

39

Why is TCP fair



R

R



ion 2

th

roughput



40

Fairness (more)

Fairness and UDP










rate R10


41

Queuing Disciplines



next



42


Simplest choice







43






44





steady-state



45






46

Design Objectives


Accommodate bursts



47

Lock-out Problem





48

Full Queues Problem





49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


8





9

How define fairness



10




11

Example


C=1 C=1

Session 1

Session 2 Session 3

Session 0

12

Notation






13

Definitions



alink crossing


allfor

allfor 0

AaCF

Ppr

aa

p

14

Definitions







15



1

2 3

4

5

213313513

12341

a

b

c

d


16



17






18





19


0=0 rp0=0 P1=P and A1=A



k(Ca-Fak-1)na



for other p rpk=rp

k-1



Ak+1


Rami Cohen

20





End

1

2 3

4

5

213313513

12341

a

b

c

d


21

Example revisited



and T31 = frac14


22




Host A

Host B

o

u

t

23











24













25





in returned RM cell

26




CongWin

Roughly






slow start


rate = CongWin

RTT Bytessec

27

TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow




28

Additive Increase





29

TCP Slow Start







30



RTT



Host A

one segment

RTT

Host B

time

two segments

four segments

31










Philosophy

32






33






34


ACK receipt for

previously unacked

data




Avoidancerdquo


CongWin every RTT

ACK receipt for

previously unacked

data

Congestion

Avoidance (CA)


(MSSCongWin)



every RTT

Loss event detected

by triple duplicate

ACK


CongWin = Threshold


Avoidancerdquo





CongWin = 1 MSS


Enter slow start




changed

35

TCP Futures




p = 210-10


pRTT

MSS221

36




losssuccess

37

TCP Model Contd


22123 C

38


TCP connection 1

bottleneckrouter

capacity R

TCP connection 2

TCP Fairness

39

Why is TCP fair



R

R



ion 2

th

roughput



40

Fairness (more)

Fairness and UDP










rate R10


41

Queuing Disciplines



next



42


Simplest choice







43






44





steady-state



45






46

Design Objectives


Accommodate bursts



47

Lock-out Problem





48

Full Queues Problem





49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


9

How define fairness



10




11

Example


C=1 C=1

Session 1

Session 2 Session 3

Session 0

12

Notation






13

Definitions



alink crossing


allfor

allfor 0

AaCF

Ppr

aa

p

14

Definitions







15



1

2 3

4

5

213313513

12341

a

b

c

d


16



17






18





19


0=0 rp0=0 P1=P and A1=A



k(Ca-Fak-1)na



for other p rpk=rp

k-1



Ak+1


Rami Cohen

20





End

1

2 3

4

5

213313513

12341

a

b

c

d


21

Example revisited



and T31 = frac14


22




Host A

Host B

o

u

t

23











24













25





in returned RM cell

26




CongWin

Roughly






slow start


rate = CongWin

RTT Bytessec

27

TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow




28

Additive Increase





29

TCP Slow Start







30



RTT



Host A

one segment

RTT

Host B

time

two segments

four segments

31










Philosophy

32






33






34


ACK receipt for

previously unacked

data




Avoidancerdquo


CongWin every RTT

ACK receipt for

previously unacked

data

Congestion

Avoidance (CA)


(MSSCongWin)



every RTT

Loss event detected

by triple duplicate

ACK


CongWin = Threshold


Avoidancerdquo





CongWin = 1 MSS


Enter slow start




changed

35

TCP Futures




p = 210-10


pRTT

MSS221

36




losssuccess

37

TCP Model Contd


22123 C

38


TCP connection 1

bottleneckrouter

capacity R

TCP connection 2

TCP Fairness

39

Why is TCP fair



R

R



ion 2

th

roughput



40

Fairness (more)

Fairness and UDP










rate R10


41

Queuing Disciplines



next



42


Simplest choice







43






44





steady-state



45






46

Design Objectives


Accommodate bursts



47

Lock-out Problem





48

Full Queues Problem





49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


10




11

Example


C=1 C=1

Session 1

Session 2 Session 3

Session 0

12

Notation






13

Definitions



alink crossing


allfor

allfor 0

AaCF

Ppr

aa

p

14

Definitions







15



1

2 3

4

5

213313513

12341

a

b

c

d


16



17






18





19


0=0 rp0=0 P1=P and A1=A



k(Ca-Fak-1)na



for other p rpk=rp

k-1



Ak+1


Rami Cohen

20





End

1

2 3

4

5

213313513

12341

a

b

c

d


21

Example revisited



and T31 = frac14


22




Host A

Host B

o

u

t

23











24













25





in returned RM cell

26




CongWin

Roughly






slow start


rate = CongWin

RTT Bytessec

27

TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow




28

Additive Increase





29

TCP Slow Start







30



RTT



Host A

one segment

RTT

Host B

time

two segments

four segments

31










Philosophy

32






33






34


ACK receipt for

previously unacked

data




Avoidancerdquo


CongWin every RTT

ACK receipt for

previously unacked

data

Congestion

Avoidance (CA)


(MSSCongWin)



every RTT

Loss event detected

by triple duplicate

ACK


CongWin = Threshold


Avoidancerdquo





CongWin = 1 MSS


Enter slow start




changed

35

TCP Futures




p = 210-10


pRTT

MSS221

36




losssuccess

37

TCP Model Contd


22123 C

38


TCP connection 1

bottleneckrouter

capacity R

TCP connection 2

TCP Fairness

39

Why is TCP fair



R

R



ion 2

th

roughput



40

Fairness (more)

Fairness and UDP










rate R10


41

Queuing Disciplines



next



42


Simplest choice







43






44





steady-state



45






46

Design Objectives


Accommodate bursts



47

Lock-out Problem





48

Full Queues Problem





49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


11

Example


C=1 C=1

Session 1

Session 2 Session 3

Session 0

12

Notation






13

Definitions



alink crossing


allfor

allfor 0

AaCF

Ppr

aa

p

14

Definitions







15



1

2 3

4

5

213313513

12341

a

b

c

d


16



17






18





19


0=0 rp0=0 P1=P and A1=A



k(Ca-Fak-1)na



for other p rpk=rp

k-1



Ak+1


Rami Cohen

20





End

1

2 3

4

5

213313513

12341

a

b

c

d


21

Example revisited



and T31 = frac14


22




Host A

Host B

o

u

t

23











24













25





in returned RM cell

26




CongWin

Roughly






slow start


rate = CongWin

RTT Bytessec

27

TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow




28

Additive Increase





29

TCP Slow Start







30



RTT



Host A

one segment

RTT

Host B

time

two segments

four segments

31










Philosophy

32






33






34


ACK receipt for

previously unacked

data




Avoidancerdquo


CongWin every RTT

ACK receipt for

previously unacked

data

Congestion

Avoidance (CA)


(MSSCongWin)



every RTT

Loss event detected

by triple duplicate

ACK


CongWin = Threshold


Avoidancerdquo





CongWin = 1 MSS


Enter slow start




changed

35

TCP Futures




p = 210-10


pRTT

MSS221

36




losssuccess

37

TCP Model Contd


22123 C

38


TCP connection 1

bottleneckrouter

capacity R

TCP connection 2

TCP Fairness

39

Why is TCP fair



R

R



ion 2

th

roughput



40

Fairness (more)

Fairness and UDP










rate R10


41

Queuing Disciplines



next



42


Simplest choice







43






44





steady-state



45






46

Design Objectives


Accommodate bursts



47

Lock-out Problem





48

Full Queues Problem





49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


12

Notation






13

Definitions



alink crossing


allfor

allfor 0

AaCF

Ppr

aa

p

14

Definitions







15



1

2 3

4

5

213313513

12341

a

b

c

d


16



17






18





19


0=0 rp0=0 P1=P and A1=A



k(Ca-Fak-1)na



for other p rpk=rp

k-1



Ak+1


Rami Cohen

20





End

1

2 3

4

5

213313513

12341

a

b

c

d


21

Example revisited



and T31 = frac14


22




Host A

Host B

o

u

t

23











24













25





in returned RM cell

26




CongWin

Roughly






slow start


rate = CongWin

RTT Bytessec

27

TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow




28

Additive Increase





29

TCP Slow Start







30



RTT



Host A

one segment

RTT

Host B

time

two segments

four segments

31










Philosophy

32






33






34


ACK receipt for

previously unacked

data




Avoidancerdquo


CongWin every RTT

ACK receipt for

previously unacked

data

Congestion

Avoidance (CA)


(MSSCongWin)



every RTT

Loss event detected

by triple duplicate

ACK


CongWin = Threshold


Avoidancerdquo





CongWin = 1 MSS


Enter slow start




changed

35

TCP Futures




p = 210-10


pRTT

MSS221

36




losssuccess

37

TCP Model Contd


22123 C

38


TCP connection 1

bottleneckrouter

capacity R

TCP connection 2

TCP Fairness

39

Why is TCP fair



R

R



ion 2

th

roughput



40

Fairness (more)

Fairness and UDP










rate R10


41

Queuing Disciplines



next



42


Simplest choice







43






44





steady-state



45






46

Design Objectives


Accommodate bursts



47

Lock-out Problem





48

Full Queues Problem





49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


13

Definitions



alink crossing


allfor

allfor 0

AaCF

Ppr

aa

p

14

Definitions







15



1

2 3

4

5

213313513

12341

a

b

c

d


16



17






18





19


0=0 rp0=0 P1=P and A1=A



k(Ca-Fak-1)na



for other p rpk=rp

k-1



Ak+1


Rami Cohen

20





End

1

2 3

4

5

213313513

12341

a

b

c

d


21

Example revisited



and T31 = frac14


22




Host A

Host B

o

u

t

23











24













25





in returned RM cell

26




CongWin

Roughly






slow start


rate = CongWin

RTT Bytessec

27

TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow




28

Additive Increase





29

TCP Slow Start







30



RTT



Host A

one segment

RTT

Host B

time

two segments

four segments

31










Philosophy

32






33






34


ACK receipt for

previously unacked

data




Avoidancerdquo


CongWin every RTT

ACK receipt for

previously unacked

data

Congestion

Avoidance (CA)


(MSSCongWin)



every RTT

Loss event detected

by triple duplicate

ACK


CongWin = Threshold


Avoidancerdquo





CongWin = 1 MSS


Enter slow start




changed

35

TCP Futures




p = 210-10


pRTT

MSS221

36




losssuccess

37

TCP Model Contd


22123 C

38


TCP connection 1

bottleneckrouter

capacity R

TCP connection 2

TCP Fairness

39

Why is TCP fair



R

R



ion 2

th

roughput



40

Fairness (more)

Fairness and UDP










rate R10


41

Queuing Disciplines



next



42


Simplest choice







43






44





steady-state



45






46

Design Objectives


Accommodate bursts



47

Lock-out Problem





48

Full Queues Problem





49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


14

Definitions







15



1

2 3

4

5

213313513

12341

a

b

c

d


16



17






18





19


0=0 rp0=0 P1=P and A1=A



k(Ca-Fak-1)na



for other p rpk=rp

k-1



Ak+1


Rami Cohen

20





End

1

2 3

4

5

213313513

12341

a

b

c

d


21

Example revisited



and T31 = frac14


22




Host A

Host B

o

u

t

23











24













25





in returned RM cell

26




CongWin

Roughly






slow start


rate = CongWin

RTT Bytessec

27

TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow




28

Additive Increase





29

TCP Slow Start







30



RTT



Host A

one segment

RTT

Host B

time

two segments

four segments

31










Philosophy

32






33






34


ACK receipt for

previously unacked

data




Avoidancerdquo


CongWin every RTT

ACK receipt for

previously unacked

data

Congestion

Avoidance (CA)


(MSSCongWin)



every RTT

Loss event detected

by triple duplicate

ACK


CongWin = Threshold


Avoidancerdquo





CongWin = 1 MSS


Enter slow start




changed

35

TCP Futures




p = 210-10


pRTT

MSS221

36




losssuccess

37

TCP Model Contd


22123 C

38


TCP connection 1

bottleneckrouter

capacity R

TCP connection 2

TCP Fairness

39

Why is TCP fair



R

R



ion 2

th

roughput



40

Fairness (more)

Fairness and UDP










rate R10


41

Queuing Disciplines



next



42


Simplest choice







43






44





steady-state



45






46

Design Objectives


Accommodate bursts



47

Lock-out Problem





48

Full Queues Problem





49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


15



1

2 3

4

5

213313513

12341

a

b

c

d


16



17






18





19


0=0 rp0=0 P1=P and A1=A



k(Ca-Fak-1)na



for other p rpk=rp

k-1



Ak+1


Rami Cohen

20





End

1

2 3

4

5

213313513

12341

a

b

c

d


21

Example revisited



and T31 = frac14


22




Host A

Host B

o

u

t

23











24













25





in returned RM cell

26




CongWin

Roughly






slow start


rate = CongWin

RTT Bytessec

27

TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow




28

Additive Increase





29

TCP Slow Start







30



RTT



Host A

one segment

RTT

Host B

time

two segments

four segments

31










Philosophy

32






33






34


ACK receipt for

previously unacked

data




Avoidancerdquo


CongWin every RTT

ACK receipt for

previously unacked

data

Congestion

Avoidance (CA)


(MSSCongWin)



every RTT

Loss event detected

by triple duplicate

ACK


CongWin = Threshold


Avoidancerdquo





CongWin = 1 MSS


Enter slow start




changed

35

TCP Futures




p = 210-10


pRTT

MSS221

36




losssuccess

37

TCP Model Contd


22123 C

38


TCP connection 1

bottleneckrouter

capacity R

TCP connection 2

TCP Fairness

39

Why is TCP fair



R

R



ion 2

th

roughput



40

Fairness (more)

Fairness and UDP










rate R10


41

Queuing Disciplines



next



42


Simplest choice







43






44





steady-state



45






46

Design Objectives


Accommodate bursts



47

Lock-out Problem





48

Full Queues Problem





49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


16



17






18





19


0=0 rp0=0 P1=P and A1=A



k(Ca-Fak-1)na



for other p rpk=rp

k-1



Ak+1


Rami Cohen

20





End

1

2 3

4

5

213313513

12341

a

b

c

d


21

Example revisited



and T31 = frac14


22




Host A

Host B

o

u

t

23











24













25





in returned RM cell

26




CongWin

Roughly






slow start


rate = CongWin

RTT Bytessec

27

TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow




28

Additive Increase





29

TCP Slow Start







30



RTT



Host A

one segment

RTT

Host B

time

two segments

four segments

31










Philosophy

32






33






34


ACK receipt for

previously unacked

data




Avoidancerdquo


CongWin every RTT

ACK receipt for

previously unacked

data

Congestion

Avoidance (CA)


(MSSCongWin)



every RTT

Loss event detected

by triple duplicate

ACK


CongWin = Threshold


Avoidancerdquo





CongWin = 1 MSS


Enter slow start




changed

35

TCP Futures




p = 210-10


pRTT

MSS221

36




losssuccess

37

TCP Model Contd


22123 C

38


TCP connection 1

bottleneckrouter

capacity R

TCP connection 2

TCP Fairness

39

Why is TCP fair



R

R



ion 2

th

roughput



40

Fairness (more)

Fairness and UDP










rate R10


41

Queuing Disciplines



next



42


Simplest choice







43






44





steady-state



45






46

Design Objectives


Accommodate bursts



47

Lock-out Problem





48

Full Queues Problem





49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


17






18





19


0=0 rp0=0 P1=P and A1=A



k(Ca-Fak-1)na



for other p rpk=rp

k-1



Ak+1


Rami Cohen

20





End

1

2 3

4

5

213313513

12341

a

b

c

d


21

Example revisited



and T31 = frac14


22




Host A

Host B

o

u

t

23











24













25





in returned RM cell

26




CongWin

Roughly






slow start


rate = CongWin

RTT Bytessec

27

TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow




28

Additive Increase





29

TCP Slow Start







30



RTT



Host A

one segment

RTT

Host B

time

two segments

four segments

31










Philosophy

32






33






34


ACK receipt for

previously unacked

data




Avoidancerdquo


CongWin every RTT

ACK receipt for

previously unacked

data

Congestion

Avoidance (CA)


(MSSCongWin)



every RTT

Loss event detected

by triple duplicate

ACK


CongWin = Threshold


Avoidancerdquo





CongWin = 1 MSS


Enter slow start




changed

35

TCP Futures




p = 210-10


pRTT

MSS221

36




losssuccess

37

TCP Model Contd


22123 C

38


TCP connection 1

bottleneckrouter

capacity R

TCP connection 2

TCP Fairness

39

Why is TCP fair



R

R



ion 2

th

roughput



40

Fairness (more)

Fairness and UDP










rate R10


41

Queuing Disciplines



next



42


Simplest choice







43






44





steady-state



45






46

Design Objectives


Accommodate bursts



47

Lock-out Problem





48

Full Queues Problem





49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


18





19


0=0 rp0=0 P1=P and A1=A



k(Ca-Fak-1)na



for other p rpk=rp

k-1



Ak+1


Rami Cohen

20





End

1

2 3

4

5

213313513

12341

a

b

c

d


21

Example revisited



and T31 = frac14


22




Host A

Host B

o

u

t

23











24













25





in returned RM cell

26




CongWin

Roughly






slow start


rate = CongWin

RTT Bytessec

27

TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow




28

Additive Increase





29

TCP Slow Start







30



RTT



Host A

one segment

RTT

Host B

time

two segments

four segments

31










Philosophy

32






33






34


ACK receipt for

previously unacked

data




Avoidancerdquo


CongWin every RTT

ACK receipt for

previously unacked

data

Congestion

Avoidance (CA)


(MSSCongWin)



every RTT

Loss event detected

by triple duplicate

ACK


CongWin = Threshold


Avoidancerdquo





CongWin = 1 MSS


Enter slow start




changed

35

TCP Futures




p = 210-10


pRTT

MSS221

36




losssuccess

37

TCP Model Contd


22123 C

38


TCP connection 1

bottleneckrouter

capacity R

TCP connection 2

TCP Fairness

39

Why is TCP fair



R

R



ion 2

th

roughput



40

Fairness (more)

Fairness and UDP










rate R10


41

Queuing Disciplines



next



42


Simplest choice







43






44





steady-state



45






46

Design Objectives


Accommodate bursts



47

Lock-out Problem





48

Full Queues Problem





49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


19


0=0 rp0=0 P1=P and A1=A



k(Ca-Fak-1)na



for other p rpk=rp

k-1



Ak+1


Rami Cohen

20





End

1

2 3

4

5

213313513

12341

a

b

c

d


21

Example revisited



and T31 = frac14


22




Host A

Host B

o

u

t

23











24













25





in returned RM cell

26




CongWin

Roughly






slow start


rate = CongWin

RTT Bytessec

27

TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow




28

Additive Increase





29

TCP Slow Start







30



RTT



Host A

one segment

RTT

Host B

time

two segments

four segments

31










Philosophy

32






33






34


ACK receipt for

previously unacked

data




Avoidancerdquo


CongWin every RTT

ACK receipt for

previously unacked

data

Congestion

Avoidance (CA)


(MSSCongWin)



every RTT

Loss event detected

by triple duplicate

ACK


CongWin = Threshold


Avoidancerdquo





CongWin = 1 MSS


Enter slow start




changed

35

TCP Futures




p = 210-10


pRTT

MSS221

36




losssuccess

37

TCP Model Contd


22123 C

38


TCP connection 1

bottleneckrouter

capacity R

TCP connection 2

TCP Fairness

39

Why is TCP fair



R

R



ion 2

th

roughput



40

Fairness (more)

Fairness and UDP










rate R10


41

Queuing Disciplines



next



42


Simplest choice







43






44





steady-state



45






46

Design Objectives


Accommodate bursts



47

Lock-out Problem





48

Full Queues Problem





49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


20





End

1

2 3

4

5

213313513

12341

a

b

c

d


21

Example revisited



and T31 = frac14


22




Host A

Host B

o

u

t

23











24













25





in returned RM cell

26




CongWin

Roughly






slow start


rate = CongWin

RTT Bytessec

27

TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow




28

Additive Increase





29

TCP Slow Start







30



RTT



Host A

one segment

RTT

Host B

time

two segments

four segments

31










Philosophy

32






33






34


ACK receipt for

previously unacked

data




Avoidancerdquo


CongWin every RTT

ACK receipt for

previously unacked

data

Congestion

Avoidance (CA)


(MSSCongWin)



every RTT

Loss event detected

by triple duplicate

ACK


CongWin = Threshold


Avoidancerdquo





CongWin = 1 MSS


Enter slow start




changed

35

TCP Futures




p = 210-10


pRTT

MSS221

36




losssuccess

37

TCP Model Contd


22123 C

38


TCP connection 1

bottleneckrouter

capacity R

TCP connection 2

TCP Fairness

39

Why is TCP fair



R

R



ion 2

th

roughput



40

Fairness (more)

Fairness and UDP










rate R10


41

Queuing Disciplines



next



42


Simplest choice







43






44





steady-state



45






46

Design Objectives


Accommodate bursts



47

Lock-out Problem





48

Full Queues Problem





49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


21

Example revisited



and T31 = frac14


22




Host A

Host B

o

u

t

23











24













25





in returned RM cell

26




CongWin

Roughly






slow start


rate = CongWin

RTT Bytessec

27

TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow




28

Additive Increase





29

TCP Slow Start







30



RTT



Host A

one segment

RTT

Host B

time

two segments

four segments

31










Philosophy

32






33






34


ACK receipt for

previously unacked

data




Avoidancerdquo


CongWin every RTT

ACK receipt for

previously unacked

data

Congestion

Avoidance (CA)


(MSSCongWin)



every RTT

Loss event detected

by triple duplicate

ACK


CongWin = Threshold


Avoidancerdquo





CongWin = 1 MSS


Enter slow start




changed

35

TCP Futures




p = 210-10


pRTT

MSS221

36




losssuccess

37

TCP Model Contd


22123 C

38


TCP connection 1

bottleneckrouter

capacity R

TCP connection 2

TCP Fairness

39

Why is TCP fair



R

R



ion 2

th

roughput



40

Fairness (more)

Fairness and UDP










rate R10


41

Queuing Disciplines



next



42


Simplest choice







43






44





steady-state



45






46

Design Objectives


Accommodate bursts



47

Lock-out Problem





48

Full Queues Problem





49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


22




Host A

Host B

o

u

t

23











24













25





in returned RM cell

26




CongWin

Roughly






slow start


rate = CongWin

RTT Bytessec

27

TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow




28

Additive Increase





29

TCP Slow Start







30



RTT



Host A

one segment

RTT

Host B

time

two segments

four segments

31










Philosophy

32






33






34


ACK receipt for

previously unacked

data




Avoidancerdquo


CongWin every RTT

ACK receipt for

previously unacked

data

Congestion

Avoidance (CA)


(MSSCongWin)



every RTT

Loss event detected

by triple duplicate

ACK


CongWin = Threshold


Avoidancerdquo





CongWin = 1 MSS


Enter slow start




changed

35

TCP Futures




p = 210-10


pRTT

MSS221

36




losssuccess

37

TCP Model Contd


22123 C

38


TCP connection 1

bottleneckrouter

capacity R

TCP connection 2

TCP Fairness

39

Why is TCP fair



R

R



ion 2

th

roughput



40

Fairness (more)

Fairness and UDP










rate R10


41

Queuing Disciplines



next



42


Simplest choice







43






44





steady-state



45






46

Design Objectives


Accommodate bursts



47

Lock-out Problem





48

Full Queues Problem





49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


23











24













25





in returned RM cell

26




CongWin

Roughly






slow start


rate = CongWin

RTT Bytessec

27

TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow




28

Additive Increase





29

TCP Slow Start







30



RTT



Host A

one segment

RTT

Host B

time

two segments

four segments

31










Philosophy

32






33






34


ACK receipt for

previously unacked

data




Avoidancerdquo


CongWin every RTT

ACK receipt for

previously unacked

data

Congestion

Avoidance (CA)


(MSSCongWin)



every RTT

Loss event detected

by triple duplicate

ACK


CongWin = Threshold


Avoidancerdquo





CongWin = 1 MSS


Enter slow start




changed

35

TCP Futures




p = 210-10


pRTT

MSS221

36




losssuccess

37

TCP Model Contd


22123 C

38


TCP connection 1

bottleneckrouter

capacity R

TCP connection 2

TCP Fairness

39

Why is TCP fair



R

R



ion 2

th

roughput



40

Fairness (more)

Fairness and UDP










rate R10


41

Queuing Disciplines



next



42


Simplest choice







43






44





steady-state



45






46

Design Objectives


Accommodate bursts



47

Lock-out Problem





48

Full Queues Problem





49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


24













25





in returned RM cell

26




CongWin

Roughly






slow start


rate = CongWin

RTT Bytessec

27

TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow




28

Additive Increase





29

TCP Slow Start







30



RTT



Host A

one segment

RTT

Host B

time

two segments

four segments

31










Philosophy

32






33






34


ACK receipt for

previously unacked

data




Avoidancerdquo


CongWin every RTT

ACK receipt for

previously unacked

data

Congestion

Avoidance (CA)


(MSSCongWin)



every RTT

Loss event detected

by triple duplicate

ACK


CongWin = Threshold


Avoidancerdquo





CongWin = 1 MSS


Enter slow start




changed

35

TCP Futures




p = 210-10


pRTT

MSS221

36




losssuccess

37

TCP Model Contd


22123 C

38


TCP connection 1

bottleneckrouter

capacity R

TCP connection 2

TCP Fairness

39

Why is TCP fair



R

R



ion 2

th

roughput



40

Fairness (more)

Fairness and UDP










rate R10


41

Queuing Disciplines



next



42


Simplest choice







43






44





steady-state



45






46

Design Objectives


Accommodate bursts



47

Lock-out Problem





48

Full Queues Problem





49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


25





in returned RM cell

26




CongWin

Roughly






slow start


rate = CongWin

RTT Bytessec

27

TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow




28

Additive Increase





29

TCP Slow Start







30



RTT



Host A

one segment

RTT

Host B

time

two segments

four segments

31










Philosophy

32






33






34


ACK receipt for

previously unacked

data




Avoidancerdquo


CongWin every RTT

ACK receipt for

previously unacked

data

Congestion

Avoidance (CA)


(MSSCongWin)



every RTT

Loss event detected

by triple duplicate

ACK


CongWin = Threshold


Avoidancerdquo





CongWin = 1 MSS


Enter slow start




changed

35

TCP Futures




p = 210-10


pRTT

MSS221

36




losssuccess

37

TCP Model Contd


22123 C

38


TCP connection 1

bottleneckrouter

capacity R

TCP connection 2

TCP Fairness

39

Why is TCP fair



R

R



ion 2

th

roughput



40

Fairness (more)

Fairness and UDP










rate R10


41

Queuing Disciplines



next



42


Simplest choice







43






44





steady-state



45






46

Design Objectives


Accommodate bursts



47

Lock-out Problem





48

Full Queues Problem





49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


26




CongWin

Roughly






slow start


rate = CongWin

RTT Bytessec

27

TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow




28

Additive Increase





29

TCP Slow Start







30



RTT



Host A

one segment

RTT

Host B

time

two segments

four segments

31










Philosophy

32






33






34


ACK receipt for

previously unacked

data




Avoidancerdquo


CongWin every RTT

ACK receipt for

previously unacked

data

Congestion

Avoidance (CA)


(MSSCongWin)



every RTT

Loss event detected

by triple duplicate

ACK


CongWin = Threshold


Avoidancerdquo





CongWin = 1 MSS


Enter slow start




changed

35

TCP Futures




p = 210-10


pRTT

MSS221

36




losssuccess

37

TCP Model Contd


22123 C

38


TCP connection 1

bottleneckrouter

capacity R

TCP connection 2

TCP Fairness

39

Why is TCP fair



R

R



ion 2

th

roughput



40

Fairness (more)

Fairness and UDP










rate R10


41

Queuing Disciplines



next



42


Simplest choice







43






44





steady-state



45






46

Design Objectives


Accommodate bursts



47

Lock-out Problem





48

Full Queues Problem





49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


27

TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow




28

Additive Increase





29

TCP Slow Start







30



RTT



Host A

one segment

RTT

Host B

time

two segments

four segments

31










Philosophy

32






33






34


ACK receipt for

previously unacked

data




Avoidancerdquo


CongWin every RTT

ACK receipt for

previously unacked

data

Congestion

Avoidance (CA)


(MSSCongWin)



every RTT

Loss event detected

by triple duplicate

ACK


CongWin = Threshold


Avoidancerdquo





CongWin = 1 MSS


Enter slow start




changed

35

TCP Futures




p = 210-10


pRTT

MSS221

36




losssuccess

37

TCP Model Contd


22123 C

38


TCP connection 1

bottleneckrouter

capacity R

TCP connection 2

TCP Fairness

39

Why is TCP fair



R

R



ion 2

th

roughput



40

Fairness (more)

Fairness and UDP










rate R10


41

Queuing Disciplines



next



42


Simplest choice







43






44





steady-state



45






46

Design Objectives


Accommodate bursts



47

Lock-out Problem





48

Full Queues Problem





49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


28

Additive Increase





29

TCP Slow Start







30



RTT



Host A

one segment

RTT

Host B

time

two segments

four segments

31










Philosophy

32






33






34


ACK receipt for

previously unacked

data




Avoidancerdquo


CongWin every RTT

ACK receipt for

previously unacked

data

Congestion

Avoidance (CA)


(MSSCongWin)



every RTT

Loss event detected

by triple duplicate

ACK


CongWin = Threshold


Avoidancerdquo





CongWin = 1 MSS


Enter slow start




changed

35

TCP Futures




p = 210-10


pRTT

MSS221

36




losssuccess

37

TCP Model Contd


22123 C

38


TCP connection 1

bottleneckrouter

capacity R

TCP connection 2

TCP Fairness

39

Why is TCP fair



R

R



ion 2

th

roughput



40

Fairness (more)

Fairness and UDP










rate R10


41

Queuing Disciplines



next



42


Simplest choice







43






44





steady-state



45






46

Design Objectives


Accommodate bursts



47

Lock-out Problem





48

Full Queues Problem





49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


29

TCP Slow Start







30



RTT



Host A

one segment

RTT

Host B

time

two segments

four segments

31










Philosophy

32






33






34


ACK receipt for

previously unacked

data




Avoidancerdquo


CongWin every RTT

ACK receipt for

previously unacked

data

Congestion

Avoidance (CA)


(MSSCongWin)



every RTT

Loss event detected

by triple duplicate

ACK


CongWin = Threshold


Avoidancerdquo





CongWin = 1 MSS


Enter slow start




changed

35

TCP Futures




p = 210-10


pRTT

MSS221

36




losssuccess

37

TCP Model Contd


22123 C

38


TCP connection 1

bottleneckrouter

capacity R

TCP connection 2

TCP Fairness

39

Why is TCP fair



R

R



ion 2

th

roughput



40

Fairness (more)

Fairness and UDP










rate R10


41

Queuing Disciplines



next



42


Simplest choice







43






44





steady-state



45






46

Design Objectives


Accommodate bursts



47

Lock-out Problem





48

Full Queues Problem





49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


30



RTT



Host A

one segment

RTT

Host B

time

two segments

four segments

31










Philosophy

32






33






34


ACK receipt for

previously unacked

data




Avoidancerdquo


CongWin every RTT

ACK receipt for

previously unacked

data

Congestion

Avoidance (CA)


(MSSCongWin)



every RTT

Loss event detected

by triple duplicate

ACK


CongWin = Threshold


Avoidancerdquo





CongWin = 1 MSS


Enter slow start




changed

35

TCP Futures




p = 210-10


pRTT

MSS221

36




losssuccess

37

TCP Model Contd


22123 C

38


TCP connection 1

bottleneckrouter

capacity R

TCP connection 2

TCP Fairness

39

Why is TCP fair



R

R



ion 2

th

roughput



40

Fairness (more)

Fairness and UDP










rate R10


41

Queuing Disciplines



next



42


Simplest choice







43






44





steady-state



45






46

Design Objectives


Accommodate bursts



47

Lock-out Problem





48

Full Queues Problem





49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


31










Philosophy

32






33






34


ACK receipt for

previously unacked

data




Avoidancerdquo


CongWin every RTT

ACK receipt for

previously unacked

data

Congestion

Avoidance (CA)


(MSSCongWin)



every RTT

Loss event detected

by triple duplicate

ACK


CongWin = Threshold


Avoidancerdquo





CongWin = 1 MSS


Enter slow start




changed

35

TCP Futures




p = 210-10


pRTT

MSS221

36




losssuccess

37

TCP Model Contd


22123 C

38


TCP connection 1

bottleneckrouter

capacity R

TCP connection 2

TCP Fairness

39

Why is TCP fair



R

R



ion 2

th

roughput



40

Fairness (more)

Fairness and UDP










rate R10


41

Queuing Disciplines



next



42


Simplest choice







43






44





steady-state



45






46

Design Objectives


Accommodate bursts



47

Lock-out Problem





48

Full Queues Problem





49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


32






33






34


ACK receipt for

previously unacked

data




Avoidancerdquo


CongWin every RTT

ACK receipt for

previously unacked

data

Congestion

Avoidance (CA)


(MSSCongWin)



every RTT

Loss event detected

by triple duplicate

ACK


CongWin = Threshold


Avoidancerdquo





CongWin = 1 MSS


Enter slow start




changed

35

TCP Futures




p = 210-10


pRTT

MSS221

36




losssuccess

37

TCP Model Contd


22123 C

38


TCP connection 1

bottleneckrouter

capacity R

TCP connection 2

TCP Fairness

39

Why is TCP fair



R

R



ion 2

th

roughput



40

Fairness (more)

Fairness and UDP










rate R10


41

Queuing Disciplines



next



42


Simplest choice







43






44





steady-state



45






46

Design Objectives


Accommodate bursts



47

Lock-out Problem





48

Full Queues Problem





49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


33






34


ACK receipt for

previously unacked

data




Avoidancerdquo


CongWin every RTT

ACK receipt for

previously unacked

data

Congestion

Avoidance (CA)


(MSSCongWin)



every RTT

Loss event detected

by triple duplicate

ACK


CongWin = Threshold


Avoidancerdquo





CongWin = 1 MSS


Enter slow start




changed

35

TCP Futures




p = 210-10


pRTT

MSS221

36




losssuccess

37

TCP Model Contd


22123 C

38


TCP connection 1

bottleneckrouter

capacity R

TCP connection 2

TCP Fairness

39

Why is TCP fair



R

R



ion 2

th

roughput



40

Fairness (more)

Fairness and UDP










rate R10


41

Queuing Disciplines



next



42


Simplest choice







43






44





steady-state



45






46

Design Objectives


Accommodate bursts



47

Lock-out Problem





48

Full Queues Problem





49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


34


ACK receipt for

previously unacked

data




Avoidancerdquo


CongWin every RTT

ACK receipt for

previously unacked

data

Congestion

Avoidance (CA)


(MSSCongWin)



every RTT

Loss event detected

by triple duplicate

ACK


CongWin = Threshold


Avoidancerdquo





CongWin = 1 MSS


Enter slow start




changed

35

TCP Futures




p = 210-10


pRTT

MSS221

36




losssuccess

37

TCP Model Contd


22123 C

38


TCP connection 1

bottleneckrouter

capacity R

TCP connection 2

TCP Fairness

39

Why is TCP fair



R

R



ion 2

th

roughput



40

Fairness (more)

Fairness and UDP










rate R10


41

Queuing Disciplines



next



42


Simplest choice







43






44





steady-state



45






46

Design Objectives


Accommodate bursts



47

Lock-out Problem





48

Full Queues Problem





49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


35

TCP Futures




p = 210-10


pRTT

MSS221

36




losssuccess

37

TCP Model Contd


22123 C

38


TCP connection 1

bottleneckrouter

capacity R

TCP connection 2

TCP Fairness

39

Why is TCP fair



R

R



ion 2

th

roughput



40

Fairness (more)

Fairness and UDP










rate R10


41

Queuing Disciplines



next



42


Simplest choice







43






44





steady-state



45






46

Design Objectives


Accommodate bursts



47

Lock-out Problem





48

Full Queues Problem





49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


36




losssuccess

37

TCP Model Contd


22123 C

38


TCP connection 1

bottleneckrouter

capacity R

TCP connection 2

TCP Fairness

39

Why is TCP fair



R

R



ion 2

th

roughput



40

Fairness (more)

Fairness and UDP










rate R10


41

Queuing Disciplines



next



42


Simplest choice







43






44





steady-state



45






46

Design Objectives


Accommodate bursts



47

Lock-out Problem





48

Full Queues Problem





49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


37

TCP Model Contd


22123 C

38


TCP connection 1

bottleneckrouter

capacity R

TCP connection 2

TCP Fairness

39

Why is TCP fair



R

R



ion 2

th

roughput



40

Fairness (more)

Fairness and UDP










rate R10


41

Queuing Disciplines



next



42


Simplest choice







43






44





steady-state



45






46

Design Objectives


Accommodate bursts



47

Lock-out Problem





48

Full Queues Problem





49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


38


TCP connection 1

bottleneckrouter

capacity R

TCP connection 2

TCP Fairness

39

Why is TCP fair



R

R



ion 2

th

roughput



40

Fairness (more)

Fairness and UDP










rate R10


41

Queuing Disciplines



next



42


Simplest choice







43






44





steady-state



45






46

Design Objectives


Accommodate bursts



47

Lock-out Problem





48

Full Queues Problem





49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


39

Why is TCP fair



R

R



ion 2

th

roughput



40

Fairness (more)

Fairness and UDP










rate R10


41

Queuing Disciplines



next



42


Simplest choice







43






44





steady-state



45






46

Design Objectives


Accommodate bursts



47

Lock-out Problem





48

Full Queues Problem





49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


40

Fairness (more)

Fairness and UDP










rate R10


41

Queuing Disciplines



next



42


Simplest choice







43






44





steady-state



45






46

Design Objectives


Accommodate bursts



47

Lock-out Problem





48

Full Queues Problem





49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


41

Queuing Disciplines



next



42


Simplest choice







43






44





steady-state



45






46

Design Objectives


Accommodate bursts



47

Lock-out Problem





48

Full Queues Problem





49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


42


Simplest choice







43






44





steady-state



45






46

Design Objectives


Accommodate bursts



47

Lock-out Problem





48

Full Queues Problem





49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


43






44





steady-state



45






46

Design Objectives


Accommodate bursts



47

Lock-out Problem





48

Full Queues Problem





49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


44





steady-state



45






46

Design Objectives


Accommodate bursts



47

Lock-out Problem





48

Full Queues Problem





49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


45






46

Design Objectives


Accommodate bursts



47

Lock-out Problem





48

Full Queues Problem





49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


46

Design Objectives


Accommodate bursts



47

Lock-out Problem





48

Full Queues Problem





49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


47

Lock-out Problem





48

Full Queues Problem





49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


48

Full Queues Problem





49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


49





50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


50

RED Algorithm





51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


51



minth maxth

maxP

10

Avg queue length

P(drop)

52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


52







53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


53





Principle 1

54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


54





55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


55




Principle 3

56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


56




Principle 4

57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


57



58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


58







59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


59


queued packet



60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


60


multiple classes


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


61





62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


62




63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


63

DRR




64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


64





65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


65





66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


66

DWRR Example

600400300

400 400300

600300400





67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


67




have same average



68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


68

Policing Mechanisms


Average Rate




69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


69



WFQ

token rate r

bucket size b

per-flowrate R

D = bRmax

arrivingtraffic





Slide 5


Example


How define fairness


Slide 11

Notation

Definitions

Slide 14




Slide 18

Slide 19


Example revisited

Slide 22



Slide 25


TCP AIMD

Additive Increase

TCP Slow Start


Refinement

Refinement (more)



TCP Futures


TCP Model Contd

TCP Fairness

Why is TCP fair

Fairness (more)

Queuing Disciplines



Slide 44


Design Objectives

Lock-out Problem

Full Queues Problem


RED Algorithm

RED Operation




Slide 55

Slide 56





Slide 61


DRR

DWRR

Slide 65

DWRR Example

Policing Mechanisms

Slide 68


1 Week 11 TCP Congestion Control. 2 Principles of Congestion Control Congestion: r informally:...

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Transcript of 1 Week 11 TCP Congestion Control. 2 Principles of Congestion Control Congestion: r informally:...