Intro Cn Final Review
Transcript of Intro Cn Final Review
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Chapter 1 - 7Semester-End Review
Computer Networking:A Top Down ApproachFeaturing the Internet,
2nd edition.Jim Kurose, Keith RossAddison-Wesley, July2002.
A note on the use of these ppt slides:Were making these slides freely available to all (faculty, students, readers).
Theyre in powerpoint form so you can add, modify, and delete slides
(including this one) and slide content to suit your needs. They obviously
represent a lotof work on our part. In return for use, we only ask the
following:
If you use these slides (e.g., in a class) in substantially unaltered form,that you mention their source (after all, wed like people to use our book!) If you post any slides in substantially unaltered form on a www site, that
you note that they are adapted from (or perhaps identical to) our slides, and
note our copyright of this material.
Thanks and enjoy! JFK/KWR
All material copyright 1996-2002
J.F Kurose and K.W. Ross, All Rights Reserved
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Internet protocol stack
application: supporting networkapplicationsr FTP, SMTP, HTTP
transport: host-host data transferr
TCP, UDP network: routing of datagrams from
source to destinationr IP, addressing, routing, forwarding
link: data transfer between
neighboring network elementsr Error Checking, MAC, Ethernet
physical: bits on the wire
application
transport
network
link
physical
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Logical communication: Application Layer
applicationtransportnetwork
link
physical
applicationtransportnetwork
link
physical
applicationtransportnetwork
linkphysical
applicationtransportnetwork
linkphysical
networklink
physical
Take instructionsfrom user or serverprocesses
Form messages Define how application
processes interactr Messages typesr Message formatsr Message orderingr Application
dependent
Send messages to theother party at theapplication layer
Wait for returning
messages
Server Proc
User Proc
application
application
Reply
Request
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Logicalcommunication: Transport Layer
applicationtransportnetwork
linkphysical
applicationtransportnetwork
linkphysical
application
transportnetwork
linkphysical
application
transportnetwork
linkphysical
networklink
physical
mesg
mesg
Take messages fromapplication layer Form segments Define how
transport-layer
components interactr Segment formatsr In case of TCP
Reliability check Congestion
control
Send segments tothe other party atthe transport layer
Wait foracknowledgement
segt
transport
transport
ack
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Logicalcommunication: Network Layer
applicationtransportnetwork
linkphysical
applicationtransportnetwork
linkphysical
application
transportnetwork
linkphysical
application
transportnetwork
linkphysical
networklink
physical
Take segments fromtransport layer
Form datagrams Define how network-
layer components
interactr Datagram formatsr Routingr Forwarding
Send datagram tothe other party atthe network layer
network
network
network
segt
dgrm
segt
dgrm
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Logicalcommunication: Link Layer
applicationtransportnetwork
linkphysical
applicationtransportnetwork
linkphysical
application
transportnetwork
linkphysical
application
transportnetwork
linkphysical
networklink
physical
Take datagramsfrom network layer Form frames Define how link-layer
components interactr Frame formatsr Error detection
and/or correctionr Multi-Access
Controlr Link-layer
technologydependent
Send frame to theother party(ies) atthe link layer
might wait forreturning frames
link
dgrm
dgrm
frame
link
link
dgrm
frame
dgrm
link
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Physical communication
applicationtransportnetwork
linkphysical
applicationtransportnetwork
linkphysical
applicationtransportnetwork
linkphysical
applicationtransportnetwork
linkphysical
networklinkphysical
data
data
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Protocol layering and data
Each layer takes data from above adds header information to create new data unit passes new data unit to layer below
applicationtransport
networklinkphysical
applicationtransport
networklinkphysical
source destination
M
M
MM
t
tntnl
M
M
M
M
t
tntnl
message
segment
datagramframe
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Why layering?
Dealing with complex systems: explicit structure allows identification,
relationship of complex systems piecesr layered reference model for discussion
modularization eases maintenance, updating ofsystemr change of implementation of layers service
transparent to rest of systemr e.g., change in gate procedure doesnt affect
rest of system
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The network edge:
end systems (hosts):r run application programsr e.g. Web, emailr at edge of network
client/server modelr client host requests, receivesservice from always-on server
r e.g. Web browser/server;email client/server
peer-peer model:r minimal (or no) use of
dedicated serversr e.g. Gnutella, KaZaA
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The Network Core
mesh of interconnectedrouters
thefundamentalquestion: how is datatransferred through net?r circuit switching:
dedicated circuit percall: telephone net
r packet-switching: datasent thru net indiscrete chunks
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End-to-end vs. Hop-by-hop
Between the end systems Application layer
r HTTP, FTP, SMTP, DNSr Content Distribution
Transport layerr UDP and TCP:
Multiplexing Demultiplexing checksuming
r TCP
Reliable data transfer Congestion control Flow control Connection management RTT and Timeout
estimation
Between the routers (hop) Network layer
r Routing Principles: DV vs. LS
r IPv4 Addressing Forwarding Fragmentation ICMP, DHCP, NAT
r IP Routing Intra-domain (Intra-AS)
routing: RIP, OSPF Inter-domain (Inter-AS)
routing: BGPr Router Architecturer IPv6, Multicast
Link layer
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End-to-end vs. Hop-by-hop
Between the end systems Application layer
r HTTP, FTP, SMTP, DNSr P2P
Transport layerr UDP and TCP:
Multiplexing Demultiplexing checksuming
r TCP
Reliable data transfer Congestion control Flow control Connection management RTT and Timeout
estimation
Between the routers(hop)
Network layer Link layer
r Principles: Error detection and
correction MAC
r LAN
Address and ARP Ethernet
CSMA/CD
Hubs vs. switches
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End-to-end vs. Hop-by-hop
Between the end systems Application layer
r HTTP, FTP, SMTP, DNSr P2P
Transport layerr UDP and TCP:
Multiplexing Demultiplexing checksuming
r TCP
Reliable data transfer Congestion control Flow control Connection management RTT and Timeout
estimation
Between the routers(hop)
Network layer
Link layerr Principles: Error detection and
correction
MAC
r LAN Address and ARP
Ethernet
Hubs, switches
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Uni-media Networking
Data transferred over Web HTTP, FTP,SMTP, DNSr Mostly text
r Some static picturesr Few short sound clip
What other forms of data wed like tocommunicate through the Internet?r Human voice conversationsr TV broadcastr Box movies
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Multi-media Networking
Human voice conversations, TV broadcast, boxmoviesr Audio and video streamr Some playback, some liver
Some interactive, some non-interactive Internet works for all these?
r Not really! Network layer
Scheduling, IntServ, RSVP, DiffServ
r But we tried Application layer
RTSP, Internet Phone
Transport layer RTP/RTCP, SIP
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6 Chapters in a Semester
1. Overview
2. Application Layer
3. Transport Layer
4. Network Layer
5. Link Layer
6. Wireless and Mobile Networking
7. Multimedia Networking
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The Exam Problems
A number of problems Each problem contains a number of questions,
from easier to more difficultr Easier ones are to explain terms
Ex. What is parity check and how does it work?
r Intermediate ones are to solve problems based on therules
Ex. Given a 2-dimensional matrix of 0s and 1s with parityrow and column, can you tell if any bit in there is corrupted?
r Difficult ones are to compare different mechanisms Ex. Compare parity check with CRC in terms of computation
complexity and error detection rate
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Keywords: Chapter 1
Taxonomyr Packet switching vs. Circuit switchingr Statistical Multiplexingr
Datagram network vs. Virtual circuit networkStructurer ISPr NAP vs. Private peering
Nodal delay Layered reference model Payload vs. header
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Keywords: Chapter 2
Intror Application vs. application-
layer protocolr Client-server vs. peer-to-
peer paradigm
r Socketr IP address and port
numberr QoSr TCP vs. UDP
Web and HTTPr Web page vs. web objectr URLr HTTP 1.0 vs. 1.1r Cookies vs. privacyr HTTP client-side cachingr Why Web caching
FTPr Out-of-band control
EMailr SMTP vs. HTTPr
POP3 vs. IMAP DNS
r Root, local, authoritativeservers
r Iterated query
r Caching P2P system
r Centralized directory vs.decentralized directory
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Keywords: Chapter 3
Common functionalityr Multiplexing and
demultiplexingr Checksum
Reliable data transferr rdt 3.0r Stop-and-wait vs. pipelined
rdtr GBN vs. selective repeat
TCP error recoveryr SampleRTT vs.
EstimatedRTT vs. DevRTTr Fast retransmit
TCP connectionmanagementr Three-way handshake
Congestion controlr End-to-end vs. network-
assisted congestioncontrol
TCP congestion controlr
AIMDr Slow startr 3 duplicate acksr Conservative after
timeout events
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Keywords: Chapter 4
Virtual circuit vs. datagram Routing
r Global vs. decentralizedinformation
r Static vs. dynamic
LSr Oscillation problem
DVr Iterative, asynchronous,
distributed
r Good news travel fast vs.Bad news travel slowr Count to infinity problem
LS vs. DV
ASr Gateway routersr Intra-AS vs. Inter-AS
routing
IPv4r IP address vs. interface
vs. networkr Class-ful vs. CIDR
addressingr
Fragmentation vs.reassemblyr MTUr DHCPr NAT
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Keywords: Chapter 4
IP routingr Stub AS vs. multi-homed
AS vs. transit ASr Two-level routingr IGP vs. EGPr
RIP vs. OSPF vs. IGRPr BGPr Path Vector
Router architecturer Input port vs. output port
r HOL blockingr Memory vs. bus vs.
crossbar
IPv6r Changes from IPv4 to IPv6r Transition from IPv4 to
IPv6: dual stack vs.tunneling
Multicast routingr Multicast vs. unicastr IGMP v1 vs. v2r Source-specific vs. group-
shared treer
Reverse path forwardingr DVMRPr PIM dense mode vs. sparse
mode
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Keywords: Chapter 5
EDCr Error detection vs. error
correctionr EDC vs. D bitsr Parity checking vs.
Internet checksum vs. CRC MAC
r Channel partitioning vs.random access vs. takingturns
r TDMA vs. FDMA vs. CDMAr Slotted Aloha vs. pure
Aloha vs. CSMA vs.CSMA/CD
r Polling vs. token passing
LAN, physical, MAC,Ethernet addressr IP vs. LAN addressr ARP vs. DNSr ARP query vs. ARP reply
r ARP cache Ethernet
r CSMA/CDr Jam signalr Bit time
r Exponential backoffr 10Base2 vs. 10BaseT vs.
100BaseT vs. GbitEthernet
r Manchester encoding
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Keywords: Chapter 7
Applicationr Multimedia applicationr QoSr Stored A/V vs. live A/V
vs. interactive A/Vr Delay sensitive, loss
tolerantr Delay jitter
Streamingr HTTP vs. RTSPr FTP vs. RTSP
Internet phoner Talk spurtr Network loss vs. delay lossr Fixed playout delay vs.
adaptive playout delay
r FEC simple vs. FECpiggybacking vs.interleaving
Transportr RTP vs. RTCPr RTCP bandwidth scalingr SIPr 5060r SIP registrar vs. SIP
proxy
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Keywords: Chapter 7
How CDN works Next generation
Internetr RSVPr IntServ vs. DiffServ
Schedulingr FIFO vs. priority vs.
round robin vs.
weighted fairscheduling
r Token bucket vs. leakybucket
IntServr Guaranteed vs.
controlled load service
DiffServr In-profile vs. out-
profiler Expedited vs. assured
forwarding