4. Evaluation Networks
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Transcript of 4. Evaluation Networks
-
8/9/2019 4. Evaluation Networks
1/42
BasicEvaluation of
Networks
Units andParameters
Link MetricsMetrics
PeriodicTransmissions
Delay ChartsPropagation Delay
Transmission Delay
Processing Delay
Typical Charts
Pipelining
Basic Evaluation of Networks
Jose L. Muñoz, Juanjo Alins, Oscar Esparza, Jorge MataTelematics Engineering
Universitat Politècnica de Catalunya (UPC)
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8/9/2019 4. Evaluation Networks
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BasicEvaluation of
Networks
Units andParameters
Link MetricsMetrics
PeriodicTransmissions
Delay ChartsPropagation Delay
Transmission Delay
Processing Delay
Typical Charts
Pipelining
Outline
1 Units and Parameters
2 Link MetricsMetrics
Periodic Transmissions
3 Delay ChartsPropagation DelayTransmission Delay
Processing DelayTypical ChartsPipelining
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8/9/2019 4. Evaluation Networks
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BasicEvaluation of
Networks
Units andParameters
Link MetricsMetrics
PeriodicTransmissions
Delay ChartsPropagation Delay
Transmission Delay
Processing Delay
Typical Charts
Pipelining
Transmission and storage units
• Transmission rate units :• Power of 10 (in bits).• Kilo=103 Mega=10 6 Giga=10 9 Tera=10 12 , etc.•
Example 1 Mbps.• Storage units :
• Power of 2 (in bytes).• Kilo=210 (1024 ), Mega=2 20 (1024 · 1024 ),
Giga=2 30 ,Tera=2 40 ,etc.• Example: 1 MB=2
3· 2
20bits.
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BasicEvaluation of
Networks
Units andParameters
Link MetricsMetrics
PeriodicTransmissions
Delay ChartsPropagation Delay
Transmission Delay
Processing Delay
Typical Charts
Pipelining
Evaluation Parameters I• L[bits ]. Message length (bits or bytes).• T tot [s]. Total time of a message transmission (seconds).• P [bits ]. Packet (or frame) size (bits or bytes).• H [bits ]. Packet (or frame) header size (overhead) (bits
or bytes).• B [bps ]. Link or network transmission rate (bps).• T x [s]. Packet (or frame) transmission time (seconds).• T h [s]. Packet (or frame) header transmission time
(seconds).
• T d [s]. Packet (or frame) data transmission time(seconds).
• d [m]. Link distance (meters).• D [s]. Propagation delay (seconds).• V [m/ s]. Propagation speed (m/s).
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BasicEvaluation of
Networks
Units andParameters
Link MetricsMetrics
PeriodicTransmissions
Delay ChartsPropagation Delay
Transmission Delay
Processing Delay
Typical Charts
Pipelining
Evaluation Parameters II
• T p [s]. Packet (or frame) processing time (seconds).• T c [s]. Cadence Time. In a periodic transmission, time
between packets or frames (seconds).• RTT [s]. Round Trip Time , time since the sender sends
data and receives data from the other end (seconds).• ST [s]. Slot Time .• λp [pps ]. Cadence in packets (frames) per second (pps).• λb [bps ]. Cadence in bits per second (bps).• λ [bps ]. Goodput or user information bit rate in bits per
second (bps).• S [s]. Virtual or real circuit establishing and releasing
time (seconds).
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BasicEvaluation of
Networks
Units andParameters
Link MetricsMetrics
PeriodicTransmissions
Delay ChartsPropagation Delay
Transmission Delay
Processing Delay
Typical ChartsPipelining
Evaluation Parameters III
• N [adimensional ]. Number of links between origin anddestination.
• U [ %]. Link or network utilization( %).• ηlink [ %]. Link efciency ( %).• ηproto [ %]. Protocol efciency ( %).
• cs . Acronym: “ circuit switching ”.• ps . Acronym: “ packet switching ”.• dt . Acronym: “ datagram ”.• vc . Acronym: “ virtual circuit ”.
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8/9/2019 4. Evaluation Networks
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BasicEvaluation of
Networks
Units andParameters
Link MetricsMetrics
PeriodicTransmissions
Delay ChartsPropagation Delay
Transmission Delay
Processing Delay
Typical ChartsPipelining
Outline
1 Units and Parameters
2 Link MetricsMetricsPeriodic Transmissions
3 Delay ChartsPropagation DelayTransmission Delay
Processing DelayTypical ChartsPipelining
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8/9/2019 4. Evaluation Networks
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BasicEvaluation of
Networks
Units andParameters
Link MetricsMetrics
PeriodicTransmissions
Delay ChartsPropagation Delay
Transmission Delay
Processing Delay
Typical ChartsPipelining
Outline
1 Units and Parameters
2 Link MetricsMetricsPeriodic Transmissions
3 Delay ChartsPropagation DelayTransmission Delay
Processing DelayTypical ChartsPipelining
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8/9/2019 4. Evaluation Networks
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BasicEvaluation of
Networks
Units andParameters
Link MetricsMetrics
PeriodicTransmissions
Delay ChartsPropagation Delay
Transmission Delay
Processing Delay
Typical ChartsPipelining
Link Metrics
H Data H Data H Data
Tobs
Link utilization (0 - 1)
U = T use T obs
Goodput (bps)
λ = Data T obs
Link efciency (0 - 1)
ηlink = T data T obs
Protocol efciency (0 - 1)
ηprot = Data Data + Overhead Note. At this moment, “protocol” is the data link layer protocol (layer 2), the
“packet” or PDU is a frame and data is data encapsualted by some user or
upperlayer in the data eld of the frame.9/42
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8/9/2019 4. Evaluation Networks
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BasicEvaluation of
Networks
Units andParameters
Link MetricsMetrics
PeriodicTransmissions
Delay ChartsPropagation Delay
Transmission Delay
Processing Delay
Typical ChartsPipelining
Outline
1 Units and Parameters
2 Link MetricsMetricsPeriodic Transmissions
3 Delay ChartsPropagation DelayTransmission Delay
Processing DelayTypical ChartsPipelining
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8/9/2019 4. Evaluation Networks
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BasicEvaluation of
Networks
Units andParameters
Link MetricsMetrics
PeriodicTransmissions
Delay ChartsPropagation Delay
Transmission Delay
Processing Delay
Typical ChartsPipelining
Periodic Transmissions
H Data H Data
Th
Td
Tx
Tc
• Time between frames or cadence time: Tc• Cadence rate ( λ c ): λc = 1/Tc [frames / sec]• Header Time: T h • Data Time: T d
U = T h + T d T c = T x T c ηlink =
T d T c λ =
Data T c ηprot =
T d T x
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BasicEvaluation of
Networks
Units andParameters
Link MetricsMetrics
PeriodicTransmissions
Delay ChartsPropagation Delay
Transmission Delay
Processing Delay
Typical ChartsPipelining
Periodic TX Example I• A is sending a bit ow of 64 kbps to C. For this purpose,
B is used as intermediate node.
A
B
C
Circuit Network
B AB
=64Kbps
Packet NetworkBBC=384Kbps
• From A to B, we use acircuit network thatprovides us with a circuitof 64 kbps.
• From B to C, we use apacket network of asingle link of 384 kbps.
• The packet network only uses the data link layer.•
B encapsulates the data of the ow into frames (withoutlosing any bit).• Frames are generated by adding a 5 Bytes header to
the user information (data of the received ow).• A frame is generated every 500 µs.
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BasicEvaluation of
Networks
Units andParameters
Link MetricsMetrics
PeriodicTransmissions
Delay ChartsPropagation Delay
Transmission Delay
Processing Delay
Typical ChartsPipelining
Periodic TX Example II
a) Calculate U , ηlink , ηprot , λ [bps ] of the BC link. A
B
C
Circuit Network
B AB
=64Kbps
Packet NetworkB
BC=384Kbps
H Data H Data
Th
Td
Tx
Tc=500μs
Data=64 kbps*500μs=32 bitsT
d=32 bits/384 kbps= 83.33μs
Tx=72 bits/384 kbps= 187.5μs
U = 187 . 5500 = 0.375 (37 .5 %)ηlink = 83 . 33500 = 0.166 (16 .6 %)
ηprot = 3272 = 0.444 (44 .4 %)λ = 32 b500 µ s = 64 kbps
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BasicEvaluation of
Networks
Units andParameters
Link MetricsMetrics
PeriodicTransmissions
Delay ChartsPropagation Delay
Transmission Delay
Processing Delay
Typical ChartsPipelining
Periodic TX Example III
b) Recalculate the parameters if we want to encapsulatethe ow using an utilization U=100 % in the packetnetwork (BC link).
U =
1 ⇒ T c =
T x
T x = 40bits + Data 384 Kbps
Data = T c · 64 Kbps
Data = 8bits T c = T x = 125 µs
U = 125125 = 1(100 %)ηprot = 848 = 0.166 (16 .6 %)
ηlink = 20 . 83125 = 0.166 (16 .6 %)λ = 8bits 125 µ s = 64Kbps
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8/9/2019 4. Evaluation Networks
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BasicEvaluation of
Networks
Units andParameters
Link MetricsMetrics
PeriodicTransmissions
Delay ChartsPropagation Delay
Transmission Delay
Processing Delay
Typical ChartsPipelining
Outline
1 Units and Parameters
2 Link MetricsMetricsPeriodic Transmissions
3 Delay ChartsPropagation DelayTransmission Delay
Processing DelayTypical ChartsPipelining
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8/9/2019 4. Evaluation Networks
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BasicEvaluation of
Networks
Units andParameters
Link MetricsMetrics
PeriodicTransmissions
Delay ChartsPropagation Delay
Transmission Delay
Processing Delay
Typical ChartsPipelining
Delay charts
• Delay-charts are a basicevaluation tool fordeterministic datatransmissions.
• Deterministic means thateverything is known.
• These charts represent:• The time on the vertical
axis.• The nodes and links in
the horizontal axis.
n
m e
n
F r a m e 1
F r a m e 1
F r a m e 2
F r a m e 2
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B i
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8/9/2019 4. Evaluation Networks
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BasicEvaluation of
Networks
Units andParameters
Link MetricsMetrics
PeriodicTransmissions
Delay ChartsPropagation Delay
Transmission Delay
Processing Delay
Typical ChartsPipelining
Outline
1 Units and Parameters
2 Link MetricsMetricsPeriodic Transmissions
3 Delay ChartsPropagation DelayTransmission Delay
Processing DelayTypical ChartsPipelining
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Basic
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8/9/2019 4. Evaluation Networks
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BasicEvaluation of
Networks
Units andParameters
Link MetricsMetrics
PeriodicTransmissions
Delay ChartsPropagation Delay
Transmission Delay
Processing Delay
Typical ChartsPipelining
Propagation delay
• The propagation Delay(D) is the amount oftime that it takes for thehead of the signal totravel from the sender tothe receiver through acertain medium.
DF r a m e
• D is the sum of two magnitudes D = D 1 + D 2 .• D 1 is calculated as a ratio between the link length d
(meters or kilometers) and the propagation speed of themedium V : D 1 = d V .• D 2 : It’s the delay introduced by physical repeaters.
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Basic
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8/9/2019 4. Evaluation Networks
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BasicEvaluation of
Networks
Units andParameters
Link MetricsMetrics
PeriodicTransmissions
Delay ChartsPropagation Delay
Transmission Delay
Processing Delay
Typical ChartsPipelining
Outline
1 Units and Parameters
2 Link MetricsMetricsPeriodic Transmissions
3 Delay ChartsPropagation DelayTransmission Delay
Processing DelayTypical ChartsPipelining
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Basic
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8/9/2019 4. Evaluation Networks
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BasicEvaluation of
Networks
Units andParameters
Link MetricsMetrics
PeriodicTransmissions
Delay ChartsPropagation Delay
Transmission Delay
Processing Delay
Typical ChartsPipelining
Transmission time
• The transmission time(T x ) is the amount oftime required to push allthe bits of informationthat we want to transmitinto the transmissionmedium.
Tx
F r a m e
• T x is calculated as the ratio between the length of theinformation L (in bits) to transmit and the transmissionrate of the link B (in bits per second or bps): T x = LB .
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Basic
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8/9/2019 4. Evaluation Networks
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BasicEvaluation of
Networks
Units andParameters
Link MetricsMetrics
PeriodicTransmissions
Delay ChartsPropagation Delay
Transmission Delay
Processing Delay
Typical ChartsPipelining
Outline
1 Units and Parameters
2 Link MetricsMetricsPeriodic Transmissions
3 Delay ChartsPropagation DelayTransmission Delay
Processing DelayTypical ChartsPipelining
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Basic
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8/9/2019 4. Evaluation Networks
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Evaluation ofNetworks
Units andParameters
Link MetricsMetrics
PeriodicTransmissions
Delay ChartsPropagation Delay
Transmission Delay
Processing Delay
Typical ChartsPipelining
Processing delay I
• The processing delay ( T p ) is the amount of time that a
node needs to process the overhead .
link-1
link-4
link-2
link-3
…
Demuxlink-1
If-0
…Demuxlink-n
If-1
OS
Muxlink-1
Muxlink-n
Typical model
• Typically, processing the overhead is partly done by thenetwork card (network interface) and partly by the OS.
• The network interface processes the layer 2 overhead(layer 2 CPU), while the Operating System (centralCPU) processes the upper layers.
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Basic
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Evaluation ofNetworks
Units andParameters
Link MetricsMetrics
PeriodicTransmissions
Delay ChartsPropagation Delay
Transmission Delay
Processing Delay
Typical ChartsPipelining
Processing delay II• Store & Forward (S&F) :
•
To process the frame, thenode must receive theentire frame.
• A node cannot processmore than one frame at atime.
• While the node isprocessing a frame, it maybe receiving or transmittingother frames.
Tp
F r a m e
F r a m e
• Another mechanism is cut & throught (C&T), in whichthe header is processed as soon as it is received andthe frame might be forwarded without waiting to itscomplete reception.
• Unless otherwise stated, we will always consider S&F .
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Basic
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Evaluation ofNetworks
Units andParameters
Link MetricsMetrics
PeriodicTransmissions
Delay ChartsPropagation Delay
Transmission Delay
Processing Delay
Typical ChartsPipelining
Store & Forwardof Messages
B
M
B B
• The message must be completely received beforebeing forwarded.
• Simple example: indirect communication through 3links:
•
With T p ≈ 0 and negligible propagation delay ( D ≈ 0).• Link B = 1.5 Mbps• Message M length L = 7500000 bits• It takes L/ B = 5s to transmit the message on each link.• Total time to transmit the message = 15 s
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Basic
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8/9/2019 4. Evaluation Networks
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Evaluation ofNetworks
Units andParameters
Link MetricsMetrics
PeriodicTransmissions
Delay ChartsPropagation Delay
Transmission Delay
Processing Delay
Typical ChartsPipelining
Store & Forwardof Frames
B B B
. . .P1P5000
• Following the previous example:• Message length M size 7500000 bits.• Frame P has a size of 1500 bits.• B = 1.5 Mbps• Avoiding header’s size, we have to send 7.5 M / 1.5 K =
5000 frames.• Each frame is transmitted in 1ms.• With S&F, T p ≈ 0 and D ≈ 0• The total time to transmit the message = 5.002s
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Basicl f
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8/9/2019 4. Evaluation Networks
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Evaluation ofNetworks
Units andParameters
Link MetricsMetrics
PeriodicTransmissions
Delay ChartsPropagation Delay
Transmission Delay
Processing Delay
Typical Charts
Pipelining
Outline
1 Units and Parameters
2 Link MetricsMetricsPeriodic Transmissions
3 Delay ChartsPropagation DelayTransmission Delay
Processing DelayTypical ChartsPipelining
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BasicE l i f
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8/9/2019 4. Evaluation Networks
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Evaluation ofNetworks
Units andParameters
Link MetricsMetrics
PeriodicTransmissions
Delay ChartsPropagation Delay
Transmission Delay
Processing Delay
Typical Charts
Pipelining
Circuit switching
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BasicEvaluation of
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8/9/2019 4. Evaluation Networks
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Evaluation ofNetworks
Units andParameters
Link MetricsMetrics
PeriodicTransmissions
Delay ChartsPropagation Delay
Transmission Delay
Processing Delay
Typical Charts
Pipelining
Datagram packet switching
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BasicEvaluation of
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8/9/2019 4. Evaluation Networks
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Evaluation ofNetworks
Units andParameters
Link MetricsMetrics
PeriodicTransmissions
Delay ChartsPropagation Delay
Transmission Delay
Processing Delay
Typical Charts
Pipelining
Virtual circuit packet switching
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BasicEvaluation of
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8/9/2019 4. Evaluation Networks
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Evaluation ofNetworks
Units andParameters
Link MetricsMetrics
PeriodicTransmissions
Delay ChartsPropagation Delay
Transmission Delay
Processing Delay
Typical Charts
Pipelining
Outline
1 Units and Parameters
2 Link MetricsMetricsPeriodic Transmissions
3 Delay ChartsPropagation DelayTransmission Delay
Processing DelayTypical ChartsPipelining
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BasicEvaluation of
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8/9/2019 4. Evaluation Networks
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Evaluation ofNetworks
Units andParameters
Link MetricsMetrics
PeriodicTransmissions
Delay ChartsPropagation Delay
Transmission Delay
Processing Delay
Typical Charts
Pipelining
Pipelining
• Packet networks can be understood as a pipeline .• In general, a pipeline is:
• A set of data processing elements connected in series.• The output of one element is the input of the next one.• The elements of a pipeline execute in parallel.• Some amount of buffer storage is often inserted
between elements.• Each element in the pipeline requires a certain amount
of time to process the input and obtain the output.• In the case of networks, inputs and outputs are PDUs.• The processing delay is due to processing the overhead
of the PDU, or to the transmission of the PDU.
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BasicEvaluation of
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8/9/2019 4. Evaluation Networks
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Networks
Units andParameters
Link MetricsMetrics
PeriodicTransmissions
Delay ChartsPropagation Delay
Transmission Delay
Processing Delay
Typical Charts
Pipelining
Pipelining Toy Example I
A
Tires andchassis
1 hour 3 hours 2 hours
B
Engine C
Body
• Some questions may arise:• How much it takes to get the rst car from the factory?• How many cars per hour can we produce?•
What happens with the queues?• Who has spare time?• How can we optimize this pipeline?• How can we analyze it? We will use a delay chart .
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BasicEvaluation of
Pi li i T E l III
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Networks
Units andParameters
Link MetricsMetrics
PeriodicTransmissions
Delay ChartsPropagation Delay
Transmission Delay
Processing Delay
Typical Charts
Pipelining
Pipelining Toy Example III
5
1 1h
2
3
4
A
5
6
7
8
0h
1h
8h
C
1
2
2
3
1
4
90h
1h
3
4
5
9
9
B out
3h
2h
...
...
...
...
i
i23
j45678
k5678
6
7
8
...
7h
j
k
• The rst car:1h+3h+2h=6h
• Cars per hour (cph):0.33cph
• What happens with thequeues? Up to 4 units
in the queue of node Cand up to 3 units in thequeue of node B.
• Who has spare time? Aand C. Now C also hashis spare time alltogether.
• How can we optimizethis pipeline? Let’s trywith other elements inthe pipeline.
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BasicEvaluation of
Pi li i T E l IV
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Networks
Units andParameters
Link MetricsMetrics
PeriodicTransmissions
Delay ChartsPropagation Delay
Transmission Delay
Processing Delay
Typical Charts
Pipelining
Pipelining Toy Example IV• More elements or more powerful elements?
1 hour 3 hours
1 hour 1 hour 1 hour
1 hour
(a) Equivalent toserial CPUs
(b) Equivalentto a faster CPU
1Ghz 1Ghz 1Ghz
1Ghz 3Ghz
1Ghz
1 hour
or
• Several serial elements in the pipeline (a) of a powerequivalent to a single element (b) (parallel operations)provide the same cadence time.
• However, (a) introduces more initial delay than (b).
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BasicEvaluation of
Pi li i ith F I
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Networks
Units andParameters
Link MetricsMetrics
PeriodicTransmissions
Delay ChartsPropagation Delay
Transmission Delay
Processing Delay
Typical Charts
Pipelining
Pipelining with Frames I
1 0.122ms
2
3
4
src
5
6
7
8
0
11.22ms
i234567
9
10
11
12
13
...
i
891011
int dstn
1.22ms
n
• Link 1 has a bit rateB 1 = 100 Mbps .
• Link 2 has a bit rateB 2 = 10 Mbps ..
• We transmit frames of size
1526 Bytes a .• Processing delay is not
considered: T p ≈ 0.• Propagation delay is not
considered: D ≈
0.• T 100 Mbps x = 0.122 ms .• T 10 Mbps x = 1.22 ms .a This is the size of a typical Ethernet fra
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BasicEvaluation of
N k Pi li i g ith F II
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8/9/2019 4. Evaluation Networks
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Networks
Units andParameters
Link MetricsMetrics
PeriodicTransmissions
Delay ChartsPropagation Delay
Transmission Delay
Processing Delay
Typical Charts
Pipelining
Pipelining with Frames II• Consider that the two links
have a bit rate B 1 = 100 Mbps .• Propagation delay: D ≈ 0.• If T x = X , we consider a
processing delay: T p = 2 · X .• This processing delay affects
the network cadence? YESbecause the processing delayis per frame (packet).
• When processing doesn’t limit
cadence, we can achieve a100 % link utilization .
• Devices whose processingdoesn’t limit cadence are saidto run at “wire speed” .
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BasicEvaluation of
N t k Pipelining with Frames III
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8/9/2019 4. Evaluation Networks
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Networks
Units andParameters
Link MetricsMetrics
PeriodicTransmissions
Delay ChartsPropagation Delay
Transmission Delay
Processing Delay
Typical Charts
Pipelining
Pipelining with Frames III
src0
int dst
link1
Tx=X
D=2X
Tc=Tx=X
......
1234 1
23
X X
link2 • The two links have a bitrate B 1 = 100 Mbps .
• Processing delay: T p ≈ 0.• T x = X and the
propagation delay
D = 2 · X .• The propagation delay
affects the networkcadence? NO because
propagation introduces adelay in the reception ofthe whole signal, but it isnot a per frame delay.
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BasicEvaluation of
Networks In Summary
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8/9/2019 4. Evaluation Networks
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Networks
Units andParameters
Link MetricsMetrics
PeriodicTransmissions
Delay ChartsPropagation Delay
Transmission Delay
Processing Delay
Typical Charts
Pipelining
In Summary
• The path that frames follow through a network can be
viewed as a pipeline.• The elements of the pipeline include:
• Overhead processing . Processors do S&F with theframe (packet) processing its overhead.
• Frame transmission . Links with different transmission
rates produce different transmission times for the sameframe (packet).• The maximum frame cadence λmax c is determined by
the slowest operation performed by any element:• The largest transmission time over the slowest link.•
The largest processing time in the slowest CPU.• T max c is max (T i x , T i p ), where i is a crossed link.• Then, λmax p = 1/ T max c .• Propagation delay doesn’t affect cadence.
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BasicEvaluation of
Networks Streaming Example I
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8/9/2019 4. Evaluation Networks
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Networks
Units andParameters
Link MetricsMetrics
PeriodicTransmissions
Delay ChartsPropagation Delay
Transmission Delay
Processing Delay
Typical Charts
Pipelining
Streaming Example I
950B50B
Frame for video streamencapsulation:
• Video streaming can be
analyzed as a pipeline.• A user wants to see a lm
of 540 MB and 90 min thatis stored on a server.
• To send the movie to the client, the server generatesframes of size 1000 Bytes with 50 Bytes of overhead.
• The server needs 6 ms to encapsulate the video dataon each frame.
• The network is formed by a link with B1=800 kbps thatconnects the server and an intermediate node and byanother link with B2=1 Mbps that connects theintermediate node with the client.
• The intermediate node requires 10 ms of processing.
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BasicEvaluation of
Networks Streaming Example II
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Networks
Units andParameters
Link MetricsMetrics
PeriodicTransmissions
Delay ChartsPropagation Delay
Transmission Delay
Processing Delay
Typical Charts
Pipelining
Streaming Example II
• In the client host, there is a video player that is able to
start playing the movie before it has been completelyreceived. This is called video streaming .
• Let’s consider that the player can set the number ofminutes to wait before starting to play the movie.
a) Calculate the lm data rate (in Kbps) that the networkcan provide.
b) Calculate the time that destination node has to wait tostart the movie in order to play it without cuts, (nomissing information at any time). This is called playouttime .
Note. Consider that frames are transmitted as quick aspossible, and links are dedicated exclusively to our videostreaming transmission.
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BasicEvaluation of
Networks Streaming Example III
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8/9/2019 4. Evaluation Networks
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etwo s
Units andParameters
Link MetricsMetrics
PeriodicTransmissions
Delay ChartsPropagation Delay
Transmission Delay
Processing Delay
Typical Charts
Pipelining
Streaming Example III
a) Film data rate:•
To play the movie, a data rate of540 · 8 · 220 / (90 · 60 ) = 838 .86 kbps are needed.• Let’s compute the goodput provided by the network.• The server takes 6 ms to generate a frame.• Link1 needs (1000 · 8)/ 800 kbps = 10 ms to transmit a
frame.• The intermediate node takes 10 ms to process a frame.• Therefore, the cadence provided by the network is
1 frame/10 ms. In kbps: 950 · 8/ 0.01 = 760 kbps .b) Playout time:
•
The missing data rate should be covered byaccumulating bytes before playing the lm.• T accum · 760 kbps = ( 838 .86 kbps − 760 kbps ) · (90 · 60 sec ).• T accum = 9.3387 min.
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