Intro Cn Final Review

8/14/2019 Intro Cn Final Review

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Review R-1

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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Review R-2

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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Review R-3

Logical communication: Application Layer

applicationtransportnetwork

link

physical


link

physical


linkphysical


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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Review R-4

Logicalcommunication: Transport Layer


linkphysical


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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Review R-5

Logicalcommunication: Network Layer


linkphysical


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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Review R-6

Logicalcommunication: Link Layer


linkphysical


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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Review R-7

Physical communication


linkphysical


linkphysical


linkphysical


linkphysical

networklinkphysical

data

data


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Review R-8

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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Review R-9

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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Review R-10

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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Review R-11

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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Review R-12

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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Review R-13



r HTTP, FTP, SMTP, DNSr P2P



r TCP


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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Review R-14



r HTTP, FTP, SMTP, DNSr P2P



r TCP


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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Review R-15

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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Review R-16

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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Review R-17

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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Review R-18

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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Review R-19

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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Review R-20

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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Review R-21

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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Review R-22

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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Review R-23

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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Review R-24

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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Review R-27

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

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Intro Cn Final Review