Chapter 5: The Data Link Layer Link Layer and LANs · · 2017-08-281 Chapter 5 Link Layer and LANs 5: DataLink Layer 5-1 A note on the use of these ppt slides: We’re making these

1

Chapter 5Link Layer and LANs

5 DataLink Layer 5-1

A note on the use of these ppt slidesWersquore making these slides freely available to all (faculty students readers) Theyrsquore 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 lot of work on our part In return for use we only ask the following

If you use these slides (eg in a class) in substantially unaltered form that you mention their source (after all wersquod 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 JFKKWR

All material copyright 1996-2007JF Kurose and KW Ross All Rights Reserved

Computer Networking A Top Down Approach 4th edition Jim Kurose Keith RossAddison-Wesley July 2007

Chapter 5 The Data Link LayerOur goals

understand principles behind data link layer services

error detection correctionsharing a broadcast channel multiple access


link layer addressingreliable data transfer flow control done

instantiation and implementation of various link layer technologies

Link Layer

51 Introduction and services52 Error detection and correction 5 3Multiple access

56 Link-layer switches57 PPP58 Link virtualization ATM MPLS


53Multiple access protocols54 Link-layer Addressing55 Ethernet

Link Layer IntroductionSome terminology

hosts and routers are nodescommunication channels that connect adjacent nodes along communication path are links

wired linksi l li k


wireless linksLANs

layer-2 packet is a frameencapsulates datagram

data-link layer has responsibility of transferring datagram from one node to adjacent node over a link

Link layer contextdatagram transferred by different link protocols over different links

eg Ethernet on first link frame relay on intermediate links 80211

l l k

transportation analogytrip from Princeton to Lausanne

limo Princeton to JFKplane JFK to Genevatrain Geneva to Lausanne


on last linkeach link protocol provides different services

eg may or may not provide rdt over link

tourist = datagramtransport segment = communication linktransportation mode = link layer protocoltravel agent = routing algorithm

Link Layer Servicesframing link access

encapsulate datagram into frame adding header trailerchannel access if shared mediumldquoMACrdquo addresses used in frame headers to identify source dest

diff t f IP dd


bull different from IP addressreliable delivery between adjacent nodes

we learned how to do this already (chapter 3)seldom used on low bit-error link (fiber some twisted pair)wireless links high error rates

bull Q why both link-level and end-end reliability

2

Link Layer Services (more)

flow controlpacing between adjacent sending and receiving nodes

error detectionerrors caused by signal attenuation noise

d f


receiver detects presence of errors bull signals sender for retransmission or drops frame

error correctionreceiver identifies and corrects bit error(s) without resorting to retransmission

half-duplex and full-duplexwith half duplex nodes at both ends of link can transmit but not at same time

Where is the link layer implemented

in each and every hostlink layer implemented in ldquoadaptorrdquo (aka network interface card NIC)

Ethernet card PCMCI cpu memory

host schematic

applicationtransportnetwork

link


card 80211 cardimplements link physical layer

attaches into hostrsquos system busescombination of hardware software firmware

controller

physicaltransmission

host bus (eg PCI)

network adaptercard

link

linkphysical

Adaptors Communicating

controller controller

sending host receiving host

datagram datagram


sending sideencapsulates datagram in frameadds error checking bits rdt flow control etc

receiving sidelooks for errors rdt flow control etcextracts datagram passes to upper layer at receiving side

datagram

frame

Link Layer

51 Introduction and services52 Error detection and correction5 3Multiple access

56 Link-layer switches57 PPP58 Link Virtualization ATM MPLS



Error DetectionEDC= Error Detection and Correction bits (redundancy)D = Data protected by error checking may include header fields

bull Error detection not 100 reliablebull protocol may miss some errors but rarelybull larger EDC field yields better detection and correction


otherwise

Parity CheckingSingle Bit ParityDetect single bit errors

Two Dimensional Bit ParityDetect and correct single bit errors


0 0

3

Internet checksum (review)

Sendertreat segment contents

Receivercompute checksum of received segment

Goal detect ldquoerrorsrdquo (eg flipped bits) in transmitted packet (note used at transport layer only)


as sequence of 16-bit integerschecksum addition (1rsquos complement sum) of segment contentssender puts checksum value into UDP checksum field

received segmentcheck if computed checksum equals checksum field value

NO - error detectedYES - no error detected But maybe errors nonetheless

Checksumming Cyclic Redundancy Checkview data bits D as a binary numberchoose r+1 bit pattern (generator) Ggoal choose r CRC bits R such that

ltDRgt exactly divisible by G (modulo 2) receiver knows G divides ltDRgt by G If non-zero remainder error detected


can detect all burst errors less than r+1 bitswidely used in practice (80211 WiFi ATM)

CRC ExampleWant

D2r XOR R = nGequivalently

D2r = nG XOR R equivalently


q yif we divide D2r by G want remainder R

R = remainder[ ]D2r

G

Link Layer





Multiple Access Links and ProtocolsTwo types of ldquolinksrdquo

point-to-pointPPP for dial-up accesspoint-to-point link between Ethernet switch and host

broadcast (shared wire or medium)old-fashioned Ethernet


old fashioned Ethernetupstream HFC80211 wireless LAN

shared wire (eg cabled Ethernet)

shared RF(eg 80211 WiFi)

shared RF(satellite)

humans at acocktail party

(shared air acoustical)

Multiple Access protocolssingle shared broadcast channel two or more simultaneous transmissions by nodes interference

collision if node receives two or more signals at the same timemultiple access protocol


distributed algorithm that determines how nodes share channel ie determine when node can transmitcommunication about channel sharing must use channel itself

no out-of-band channel for coordination

4

Ideal Multiple Access Protocol

Broadcast channel of rate R bps1 when one node wants to transmit it can send at

rate R2 when M nodes want to transmit each can send at

average rate RM


average rate RM3 fully decentralized

no special node to coordinate transmissionsno synchronization of clocks slots

4 simple

MAC Protocols a taxonomyThree broad classes

Channel Partitioningdivide channel into smaller ldquopiecesrdquo (time slots frequency code)allocate piece to node for exclusive use

Random Access


Random Accesschannel not divided allow collisionsldquorecoverrdquo from collisions

ldquoTaking turnsrdquonodes take turns but nodes with more to send can take longer turns

Channel Partitioning MAC protocols TDMA

TDMA time division multiple accessaccess to channel in rounds each station gets fixed length slot (length = pkt trans time) in each round unused slots go idle


unused slots go idle example 6-station LAN 134 have pkt slots 256 idle

1 3 4 1 3 4

6-slotframe

Channel Partitioning MAC protocols FDMA

FDMA frequency division multiple accesschannel spectrum divided into frequency bandseach station assigned fixed frequency bandunused transmission time in frequency bands go idle example 6-station LAN 1 3 4 have pkt frequency


example 6-station LAN 134 have pkt frequency bands 256 idle

freq

uenc

y ba

nds

FDM cable

Random Access Protocols

When node has packet to sendtransmit at full channel data rate Rno a priori coordination among nodes

two or more transmitting nodes ldquocollisionrdquorandom access MAC protocol specifies


random access MAC protocol specifies how to detect collisionshow to recover from collisions (eg via delayed retransmissions)

Examples of random access MAC protocolsslotted ALOHAALOHACSMA CSMACD CSMACA

Slotted ALOHA

Assumptionsall frames same sizetime divided into equal size slots (time to transmit 1 frame)

Operationwhen node obtains fresh frame transmits in next slot

if no collision node can


nodes start to transmit only slot beginning nodes are synchronizedif 2 or more nodes transmit in slot all nodes detect collision

send new frame in next slotif collision node retransmits frame in each subsequent slot with prob p until success

5

Slotted ALOHA

P s Cons


Prossingle active node can continuously transmit at full rate of channelhighly decentralized only slots in nodes need to be in syncsimple

Conscollisions wasting slotsidle slotsnodes may be able to detect collision in less than time to transmit packetclock synchronization

Slotted Aloha efficiency

suppose N nodes with

max efficiency find p that maximizes Np(1-p)N-1

for many nodes take limit of Np(1-p)N-1

as N goes to infinity

Efficiency long-run fraction of successful slots (many nodes all with many frames to send)


many frames to send each transmits in slot with probability pprob that given node has success in a slot = p(1-p)N-1

prob that any node has a success = Np(1-p)N-1

ygives

Max efficiency = 1e = 37

At best channelused for useful transmissions 37of time

Pure (unslotted) ALOHAunslotted Aloha simpler no synchronizationwhen frame first arrives

transmit immediately collision probability increases

frame sent at t0 collides with other frames sent in [t0-1t0+1]


0 [ 0 0 ]

Pure Aloha efficiencyP(success by given node) = P(node transmits)

P(no other node transmits in [p0-1p0] P(no other node transmits in [p0-1p0]

= p (1-p)N-1 (1-p)N-1

= p (1-p)2(N-1)


= p (1 p)

hellip choosing optimum p and then letting n -gt infty

= 1(2e) = 18

even worse than slotted Aloha

CSMA (Carrier Sense Multiple Access)

CSMA listen before transmitIf channel sensed idle transmit entire frame

If channel sensed busy defer transmission


human analogy donrsquot interrupt others

CSMA collisionscollisions can still occurpropagation delay means two nodes may not heareach otherrsquos transmission

collision

spatial layout of nodes


entire packet transmission time wastednoterole of distance amp propagation delay in determining collision probability

6

CSMACD (Collision Detection)CSMACD carrier sensing deferral as in CSMA

collisions detected within short timecolliding transmissions aborted reducing channel wastage

collision detection


collision detectioneasy in wired LANs measure signal strengths compare transmitted received signalsdifficult in wireless LANs received signal strength overwhelmed by local transmission strength

human analogy the polite conversationalist

CSMACD collision detection


ldquoTaking Turnsrdquo MAC protocols

channel partitioning MAC protocolsshare channel efficiently and fairly at high loadinefficient at low load delay in channel access 1N bandwidth allocated even if only 1 active node


node Random access MAC protocols

efficient at low load single node can fully utilize channelhigh load collision overhead

ldquotaking turnsrdquo protocolslook for best of both worlds

ldquoTaking Turnsrdquo MAC protocolsPolling

master node ldquoinvitesrdquo slave nodes to transmit in turntypically used with master

polldata


typically used with ldquodumbrdquo slave devicesconcerns

polling overhead latencysingle point of failure (master)

slaves

data

ldquoTaking Turnsrdquo MAC protocolsToken passing

control token passed from one node to next sequentiallytoken message

T

(nothing


concernstoken overhead latencysingle point of failure (token)

data

to send)T

Summary of MAC protocols

channel partitioning by time frequency or codeTime Division Frequency Division

random access (dynamic) ALOHA S-ALOHA CSMA CSMACDcarrier sensing easy in some technologies (wire) hard in


carrier sensing easy in some technologies (wire) hard in others (wireless)CSMACD used in EthernetCSMACA used in 80211

taking turnspolling from central site token passingBluetooth FDDI IBM Token Ring

7

LAN technologiesData link layer so far

services error detectioncorrection multiple access

Next LAN technologiesaddressing


addressingEthernetswitchesPPP

Link Layer




53Multiple access protocols54 Link-Layer Addressing55 Ethernet

MAC Addresses and ARP

32-bit IP address network-layer addressused to get datagram to destination IP subnet

MAC (or LAN or physical or Ethernet)


MAC (or LAN or physical or Ethernet) address

function get frame from one interface to another physically-connected interface (same network)48 bit MAC address (for most LANs)

bull burned in NIC ROM also sometimes software settable

LAN Addresses and ARPEach adapter on LAN has unique LAN address

Broadcast address =FF-FF-FF-FF-FF-FF

1A-2F-BB-76-09-AD


= adapter

58-23-D7-FA-20-B0

0C-C4-11-6F-E3-98

71-65-F7-2B-08-53

LAN(wired orwireless)

LAN Address (more)

MAC address allocation administered by IEEEmanufacturer buys portion of MAC address space (to assure uniqueness)analogy

( ) MAC dd lik S i l S it N b


(a) MAC address like Social Security Number(b) IP address like postal address

MAC flat address portability can move LAN card from one LAN to another

IP hierarchical address NOT portableaddress depends on IP subnet to which node is attached

ARP Address Resolution Protocol

Each IP node (host router) on LAN has ARP tableARP table IPMAC address mappings for

Question how to determineMAC address of Bknowing Brsquos IP address

137196778


pp gsome LAN nodes

lt IP address MAC address TTLgtTTL (Time To Live) time after which address mapping will be forgotten (typically 20 min)

1A-2F-BB-76-09-AD

58-23-D7-FA-20-B0

0C-C4-11-6F-E3-98

71-65-F7-2B-08-53

LAN

137196723 137196714

137196788

8

ARP protocol Same LAN (network)

A wants to send datagram to B and Brsquos MAC address not in Arsquos ARP tableA broadcasts ARP query packet containing Bs IP address

dest MAC address = FF

A caches (saves) IP-to-MAC address pair in its ARP table until information becomes old (times out)

soft state information that times out (goes


dest MAC address = FF-FF-FF-FF-FF-FFall machines on LAN receive ARP query

B receives ARP packet replies to A with its (Bs) MAC address

frame sent to Arsquos MAC address (unicast)

that times out (goes away) unless refreshed

ARP is ldquoplug-and-playrdquonodes create their ARP tables without intervention from net administrator

DHCP Dynamic Host Configuration Protocol

Goal allow host to dynamically obtain its IP address from network server when joining network

support for mobile users joining networkhost holds address only while connected and ldquoonrdquo (allowing address reuse)


(allowing address reuse)renew address already in use

DHCP overview1 host broadcasts ldquoDHCP discoverrdquo msg2 DHCP server responds with ldquoDHCP offerrdquo msg3 host requests IP address ldquoDHCP requestrdquo msg4 DHCP server sends address ldquoDHCP ackrdquo msg

DHCP client-server scenario

223111

223112223114 223129

223121A DHCP server


223113223122

223132223131

2231327

BE arriving DHCP

client needsaddress in this(2231224) network

DHCP client-server scenarioDHCP server 223125 arriving

clientDHCP discover

src 0000 68 dest 25525525525567yiaddr 0000transaction ID 654

DHCP offersrc 223125 67 dest 255255255255 68yiaddrr 223124transaction ID 654


time

Lifetime 3600 secsDHCP request

src 0000 68 dest 255255255255 67yiaddrr 223124transaction ID 655Lifetime 3600 secs

DHCP ACKsrc 223125 67 dest 255255255255 68yiaddrr 223124transaction ID 655Lifetime 3600 secs

Addressing routing to another LAN

1A-23-F9-CD-06-9BE6-E9-00-17-BB-4B

111111111111

A74-29-9C-E8-FF-55

222222222221

88-B2-2F-54-1A-0F

walkthrough send datagram from A to B via Rassume A knows Brsquos IP address


R

222222222220111111111110

CC-49-DE-D0-AB-7D

111111111112B

222222222222

49-BD-D2-C7-56-2A

two ARP tables in router R one for each IP network (LAN)

A creates IP datagram with source A destination B A uses ARP to get Rrsquos MAC address for 111111111110A creates link-layer frame with Rs MAC address as dest frame contains A-to-B IP datagramArsquos NIC sends frame Rrsquos NIC receives frame R removes IP datagram from Ethernet frame sees its destined to BR uses ARP to get Brsquos MAC address

This is a really importantexample ndash make sure youunderstand


gR creates frame containing A-to-B IP datagram sends to B

R

1A-23-F9-CD-06-9B

222222222220111111111110

E6-E9-00-17-BB-4B

CC-49-DE-D0-AB-7D

111111111112

111111111111

A74-29-9C-E8-FF-55

222222222221

88-B2-2F-54-1A-0F

B222222222222

49-BD-D2-C7-56-2A

9

Link Layer


56 Link-layer switches57 PPP58 Link Virtualization ATM and MPLS



Ethernetldquodominantrdquo wired LAN technology

cheap $20 for NICfirst widely used LAN technologysimpler cheaper than token LANs and ATMkept up with speed race 10 Mbps ndash 10 Gbps


p p p p p

Metcalfersquos Ethernetsketch

Star topologybus topology popular through mid 90s

all nodes in same collision domain (can collide with each other)

today star topology prevailsactive switch in centereach ldquospokerdquo runs a (separate) Ethernet protocol (nodes do not collide with each other)


switch

bus coaxial cable star

Ethernet Frame StructureSending adapter encapsulates IP datagram (or other

network layer protocol packet) in Ethernet frame


Preamble7 bytes with pattern 10101010 followed by one byte with pattern 10101011used to synchronize receiver sender clock rates

Ethernet Frame Structure (more)Addresses 6 bytes

if adapter receives frame with matching destination address or with broadcast address (eg ARP packet) it passes data in frame to network layer protocolotherwise adapter discards frame

Type indicates higher layer protocol (mostly IP


Type indicates higher layer protocol (mostly IP but others possible eg Novell IPX AppleTalk)CRC checked at receiver if error is detected frame is dropped

Ethernet Unreliable connectionless

connectionless No handshaking between sending and receiving NICs unreliable receiving NIC doesnrsquot send acks or nacks to sending NIC

stream of datagrams passed to network layer can have gaps


stream of datagrams passed to network layer can have gaps (missing datagrams)gaps will be filled if app is using TCPotherwise app will see gaps

Ethernetrsquos MAC protocol unslotted CSMACD

10

Ethernet CSMACD algorithm1 NIC receives datagram

from network layer creates frame

2 If NIC senses channel idle starts frame transmission If NIC senses channel

4 If NIC detects another transmission while transmitting aborts and sends jam signal

5 After aborting NIC enters exponential


If NIC senses channel busy waits until channel idle then transmits

3 If NIC transmits entire frame without detecting another transmission NIC is done with frame

enters exponential backoff after mth collision NIC chooses K at random from 012hellip2m-1 NIC waits K512 bit times returns to Step 2

Ethernetrsquos CSMACD (more)Jam Signal make sure all

other transmitters are aware of collision 48 bits

Bit time 1 microsec for 10 Mbps Ethernet for K=1023 wait time is about 50 msec

Exponential BackoffGoal adapt retransmission attempts to estimated current load

heavy load random wait will be longer


about 50 msec first collision choose K from 01 delay is K 512 bit transmission timesafter second collision choose K from 0123hellipafter ten collisions choose K from 01234hellip1023

Seeinteract with Javaapplet on AWL Web sitehighly recommended

CSMACD efficiency

Tprop = max prop delay between 2 nodes in LANttrans = time to transmit max-size frame

efficiency 1=


efficiency goes to 1 as tprop goes to 0as ttrans goes to infinity

better performance than ALOHA and simple cheap decentralized

transprop ttff y

51+

8023 Ethernet Standards Link amp Physical Layers

many different Ethernet standardscommon MAC protocol and frame formatdifferent speeds 2 Mbps 10 Mbps 100 Mbps 1Gbps 10G bpsdifferent physical layer media fiber cable



linkphysical

MAC protocoland frame format

100BASE-TX

100BASE-T4

100BASE-FX100BASE-T2

100BASE-SX 100BASE-BX

fiber physical layercopper (twisterpair) physical layer

Manchester encoding


used in 10BaseTeach bit has a transitionallows clocks in sending and receiving nodes to synchronize to each other

no need for a centralized global clock among nodesHey this is physical-layer stuff

Link Layer

51 Introduction and services52 Error detection and correction 5 3 Multiple access



53 Multiple access protocols54 Link-layer Addressing55 Ethernet

11

Hubshellip physical-layer (ldquodumbrdquo) repeaters

bits coming in one link go out all other links at same rateall nodes connected to hub can collide with one anotherno frame buffering


gno CSMACD at hub host NICs detect collisions

twisted pair

hub

Switchlink-layer device smarter than hubs take active role

store forward Ethernet framesexamine incoming framersquos MAC address selectively forward frame to one-or-more

l k h f f


outgoing links when frame is to be forwarded on segment uses CSMACD to access segment

transparenthosts are unaware of presence of switches

plug-and-play self-learningswitches do not need to be configured

Switch allows multiple simultaneous transmissions

hosts have dedicated direct connection to switchswitches buffer packetsEthernet protocol used on each incoming link but no

A

BCrsquo

1 2 345

6


each incoming link but no collisions full duplex

each link is its own collision domain

switching A-to-Arsquo and B-to-Brsquo simultaneously without collisions

not possible with dumb hub

ArsquoBrsquo

C

switch with six interfaces(123456)

45

Switch Table

Q how does switch know that Arsquo reachable via interface 4 Brsquo reachable via interface 5A each switch has a switch table each entry

A

BCrsquo

1 2 345

6


ta ach ntry(MAC address of host interface to reach host time stamp)

looks like a routing tableQ how are entries created maintained in switch table

something like a routing protocol

ArsquoBrsquo

C


45

Switch self-learning

switch learns which hosts can be reached through which interfaces

when frame received switch ldquolearnsrdquo location of

d i i LAN

A

BCrsquo

1 2 345

6

A Arsquo

Source ADest Arsquo


sender incoming LAN segmentrecords senderlocation pair in switch table

ArsquoBrsquo

C

45

MAC addr interface TTLSwitch table

(initially empty)A 1 60

Switch frame filteringforwardingWhen frame received

1 record link associated with sending host2 index switch table using MAC dest address3 if entry found for destination

then


then if dest on segment from which frame arrived

then drop the frameelse forward the frame on interface indicated

else flood forward on all but the interface

on which the frame arrived

12

Self-learning forwarding example

A

BCrsquo

1 2 345

6

A Arsquo

Source ADest Arsquo

A ArsquoA ArsquoA ArsquoA ArsquoA Arsquoframe destination unknown floodd ti ti A


ArsquoBrsquo

C

45



Arsquo A

destination A location known

Arsquo 4 60

selective send

Interconnecting switches

switches can be connected together

A

B

S1

C DF

S2

S4

S3

I


B

Q sending from A to F - how does S1 know to forward frame destined to F via S4 and S3A self learning (works exactly the same as in single-switch case)

C D

E HI

G

Self-learning multi-switch exampleSuppose C sends frame to I I responds to C

A

B

S1

C DF

S2

S4

S3

I

12


Q show switch tables and packet forwarding in S1 S2 S3 S4

B C D

E HI

G

Institutional network

to externalnetwork

router

mail server

web server


IP subnet

Switches vs Routersboth store-and-forward devices

routers network layer devices (examine network layer headers)switches are link layer devices

routers maintain routing tables implement routing algorithms


gswitches maintain switch tables implement filtering learning algorithms

Summary comparison

hubs routers switches

traffic isolation

no yes yes


solat on plug amp play yes no yes

optimal routing

no yes no

cut through

yes no yes

13

Link Layer


56 Hubs and switches57 PPP58 Link Virtualization ATM



Point to Point Data Link Controlone sender one receiver one link easier than broadcast link

no Media Access Controlno need for explicit MAC addressinge g dialup link ISDN line


eg dialup link ISDN linepopular point-to-point DLC protocols

PPP (point-to-point protocol)HDLC High level data link control (Data link used to be considered ldquohigh layerrdquo in protocol stack

PPP Design Requirements [RFC 1557]

packet framing encapsulation of network-layer datagram in data link frame

carry network layer data of any network layer protocol (not just IP) at same timeability to demultiplex upwards


bit transparency must carry any bit pattern in the data fielderror detection (no correction)connection liveness detect signal link failure to network layernetwork layer address negotiation endpoint can learnconfigure each otherrsquos network address

PPP non-requirements

no error correctionrecoveryno flow controlout of order delivery OK no need to support multipoint links (eg polling)


Error recovery flow control data re-ordering all relegated to higher layers

PPP Data Frame

Flag delimiter (framing)Address does nothing (only one option)Control does nothing in the future possible multiple control fieldsP t l l t l t hi h f


Protocol upper layer protocol to which frame delivered (eg PPP-LCP IP IPCP etc)

PPP Data Frame

info upper layer data being carriedcheck cyclic redundancy check for error detection


14

Byte Stuffingldquodata transparencyrdquo requirement data field must

be allowed to include flag pattern lt01111110gtQ is received lt01111110gt data or flag


Sender adds (ldquostuffsrdquo) extra lt 01111110gt byte after each lt 01111110gt data byteReceiver

two 01111110 bytes in a row discard first byte continue data receptionsingle 01111110 flag byte

Byte Stuffing

flag bytepatternin datato send


flag byte pattern plusstuffed byte in transmitted data

PPP Data Control ProtocolBefore exchanging network-

layer data data link peers mustconfigure PPP link (max frame length authentication)


authentication)learnconfigure networklayer information

for IP carry IP Control Protocol (IPCP) msgs (protocol field 8021) to configurelearn IP address

Link Layer


56 Hubs and switches57 PPP58 Link Virtualization ATM and MPLS



Virtualization of networks

Virtualization of resources powerful abstraction in systems engineeringcomputing examples virtual memory virtual devices

Virtual machines e g java


Virtual machines eg javaIBM VM os from 1960rsquos70rsquos

layering of abstractions donrsquot sweat the details of the lower layer only deal with lower layers abstractly

The Internet virtualizing networks

1974 multiple unconnected nets

ARPAnetdata-over-cable networkspacket satellite network (Aloha)

k d k

hellip differing inaddressing conventionspacket formatserror recoveryrouting


packet radio network

ARPAnet satellite netA Protocol for Packet Network Intercommunication V Cerf R Kahn IEEE Transactions on CommunicationsMay 1974 pp 637-648

15

The Internet virtualizing networksInternetwork layer (IP)

addressing internetwork appears as single uniform entity despite underlying local network heterogeneitynetwork of networks

Gateway ldquoembed internetwork packets in local packet format or extract themrdquoroute (at internetwork level) to next gateway


ARPAnet satellite net

gateway

Cerf amp Kahnrsquos Internetwork ArchitectureWhat is virtualized

two layers of addressing internetwork and local networknew layer (IP) makes everything homogeneous at internetwork layer


underlying local network technology cablesatellite56K telephone modemtoday ATM MPLS

hellip ldquoinvisiblerdquo at internetwork layer Looks like a link layer technology to IP

ATM and MPLS

ATM MPLS separate networks in their own right

different service models addressing routing from Internet


viewed by Internet as logical link connecting IP routers

just like dialup link is really part of separate network (telephone network)

ATM MPLS of technical interest in their own right

Asynchronous Transfer Mode ATM1990rsquos00 standard for high-speed (155Mbps to 622 Mbps and higher) Broadband Integrated Service Digital Network architectureGoal integrated end-end transport of carry voice video data

Q f d


meeting timingQoS requirements of voice video (versus Internet best-effort model)ldquonext generationrdquo telephony technical roots in telephone worldpacket-switching (fixed length packets called ldquocellsrdquo) using virtual circuits

ATM architecture

physical

ATM

AAL

physical

ATM

AAL

physical

ATM

physical

ATM

d d ti h it h


adaptation layer only at edge of ATM networkdata segmentationreassemblyroughly analagous to Internet transport layer

ATM layer ldquonetworkrdquo layercell switching routing

physical layer

end system end systemswitch switch

ATM network or link layerVision end-to-end

transport ldquoATM from desktop to desktoprdquo

ATM is a network technology

Reality used to connect

ATMnetwork

IPnetwork


Reality used to connect IP backbone routers

ldquoIP over ATMrdquoATM as switched link layer connecting IP routers

16

ATM Adaptation Layer (AAL)

ATM Adaptation Layer (AAL) ldquoadaptsrdquo upper layers (IP or native ATM applications) to ATM layer belowAAL present only in end systems not in switchesAAL layer segment (headertrailer fields data)


AAL layer segment (headertrailer fields data) fragmented across multiple ATM cells

analogy TCP segment in many IP packets

physical

ATM

AAL

physical

ATM

AAL

physical

ATM

physical

ATM


ATM Adaptation Layer (AAL) [more]

Different versions of AAL layers depending on ATM service classAAL1 for CBR (Constant Bit Rate) services eg circuit emulationAAL2 for VBR (Variable Bit Rate) services eg MPEG videoAAL5 for data (eg IP datagrams)


AAL PDU

ATM cell

User data

ATM LayerService transport cells across ATM network

analogous to IP network layervery different services than IP network layer

NetworkArchitecture

ServiceModel Bandwidth Loss Order Timing

Congestionfeedback

Guarantees


Internet

ATM

ATM

ATM

ATM

best effort

CBR

VBR

ABR

UBR

none

constantrateguaranteedrateguaranteed minimumnone

no

yes

yes

no

no

no

yes

yes

yes

yes

no

yes

yes

no

no

no (inferredvia loss)nocongestionnocongestionyes

no

ATM Layer Virtual CircuitsVC transport cells carried on VC from source to dest

call setup teardown for each call before data can floweach packet carries VC identifier (not destination ID)every switch on source-dest path maintain ldquostaterdquo for each passing connectionlinkswitch resources (bandwidth buffers) may be allocated to


( ff ) m yVC to get circuit-like perf

Permanent VCs (PVCs)long lasting connectionstypically ldquopermanentrdquo route between to IP routers

Switched VCs (SVC)dynamically set up on per-call basis

ATM VCsAdvantages of ATM VC approach

QoS performance guarantee for connection mapped to VC (bandwidth delay delay jitter)

Drawbacks of ATM VC approachInefficient support of datagram traffic


Inefficient support of datagram trafficone PVC between each sourcedest pair) does not scale (N2 connections needed) SVC introduces call setup latency processing overhead for short lived connections

ATM Layer ATM cell5-byte ATM cell header48-byte payload

Why small payload -gt short cell-creation delay for digitized voicehalfway between 32 and 64 (compromise)


y p

Cell header

Cell format

17

ATM cell headerVCI virtual channel ID

will change from link to link thru netPT Payload type (eg RM cell versus data cell) CLP Cell Loss Priority bit

CLP 1 i li l i it ll b


CLP = 1 implies low priority cell can be discarded if congestion

HEC Header Error Checksumcyclic redundancy check

ATM Physical Layer (more)

Two pieces (sublayers) of physical layerTransmission Convergence Sublayer (TCS) adapts ATM layer above to PMD sublayer belowPhysical Medium Dependent depends on physical medium being used


medium being used

TCS FunctionsHeader checksum generation 8 bits CRC Cell delineationWith ldquounstructuredrdquo PMD sublayer transmission of idle cells when no data cells to send

ATM Physical Layer

Physical Medium Dependent (PMD) sublayerSONETSDH transmission frame structure (like a container carrying bits)

bit synchronization


bandwidth partitions (TDM) several speeds OC3 = 15552 Mbps OC12 = 62208 Mbps OC48 = 245 Gbps OC192 = 96 Gbps

TIT3 transmission frame structure (old telephone hierarchy) 15 Mbps 45 Mbpsunstructured just cells (busyidle)

IP-Over-ATMClassic IP only

3 ldquonetworksrdquo (eg LAN segments)MAC (8023) and IP addresses

IP over ATMreplace ldquonetworkrdquo (eg LAN segment) with ATM networkATM addresses IP addresses

ATM


ATMnetwork

EthernetLANs

EthernetLANs

IP-Over-ATM

AALATMphyphy

EthIP

ATM

ATMphy

apptransport

IPAALATMphy

apptransport

IPEthphy


ATMphy

p y

Datagram Journey in IP-over-ATM Network

at Source HostIP layer maps between IP ATM dest address (using ARP)passes datagram to AAL5AAL5 encapsulates data segments cells passes to ATM layer

ATM network moves cell along VC to destination


at Destination HostAAL5 reassembles cells into original datagramif CRC OK datagram is passed to IP

18

IP-Over-ATM

IssuesIP datagrams into ATM AAL5 PDUsfrom IP addresses

TM dd

ATMnetwork


to ATM addressesjust like IP addresses to 8023 MAC addresses

EthernetLANs

Multiprotocol label switching (MPLS)

initial goal speed up IP forwarding by using fixed length label (instead of IP address) to do forwarding

borrowing ideas from Virtual Circuit (VC) approachbut IP datagram still keeps IP address


g p

PPP or Ethernet header IP header remainder of link-layer frameMPLS header

label Exp S TTL

20 3 1 5

MPLS capable routers

aka label-switched routerforwards packets to outgoing interface based only on label value (donrsquot inspect IP address)

MPLS forwarding table distinct from IP forwarding tables


tablessignaling protocol needed to set up forwarding

RSVP-TEforwarding possible along paths that IP alone would not allow (eg source-specific routing) use MPLS for traffic engineering

must co-exist with IP-only routers

in out outlabel label dest interface

10 6 A 112 9 D 0


10 A 012 D 08 A 1

MPLS forwarding tables


R1R2

DR3R4

R50

100

A

R6


6 - A 0

1


8 6 A 0

0

Chapter 5 Summaryprinciples behind data link layer services

error detection correctionsharing a broadcast channel multiple accesslink layer addressing

instantiation and implementation of various link l t h l i


layer technologiesEthernetswitched LANSPPPvirtualized networks as a link layer ATM MPLS

Chapter 5 letrsquos take a breathjourney down protocol stack complete(except PHY)solid understanding of networking principles practice

ld t h b t l t f i t ti


hellip could stop here hellip but lots of interesting topics

wirelessmultimediasecurity network management

2

Link Layer Services (more)

flow controlpacing between adjacent sending and receiving nodes

error detectionerrors caused by signal attenuation noise

d f


receiver detects presence of errors bull signals sender for retransmission or drops frame

error correctionreceiver identifies and corrects bit error(s) without resorting to retransmission

half-duplex and full-duplexwith half duplex nodes at both ends of link can transmit but not at same time

Where is the link layer implemented

in each and every hostlink layer implemented in ldquoadaptorrdquo (aka network interface card NIC)

Ethernet card PCMCI cpu memory

host schematic


link


card 80211 cardimplements link physical layer

attaches into hostrsquos system busescombination of hardware software firmware

controller

physicaltransmission

host bus (eg PCI)

network adaptercard

link

linkphysical

Adaptors Communicating

controller controller

sending host receiving host

datagram datagram


sending sideencapsulates datagram in frameadds error checking bits rdt flow control etc

receiving sidelooks for errors rdt flow control etcextracts datagram passes to upper layer at receiving side

datagram

frame

Link Layer

51 Introduction and services52 Error detection and correction5 3Multiple access




Error DetectionEDC= Error Detection and Correction bits (redundancy)D = Data protected by error checking may include header fields

bull Error detection not 100 reliablebull protocol may miss some errors but rarelybull larger EDC field yields better detection and correction


otherwise

Parity CheckingSingle Bit ParityDetect single bit errors

Two Dimensional Bit ParityDetect and correct single bit errors


0 0

3













CRC ExampleWant





R = remainder[ ]D2r

G

Link Layer




















4




average rate RM




4 simple



Random Access








1 3 4 1 3 4

6-slotframe





freq

uenc

y ba

nds

FDM cable







Slotted ALOHA







5

Slotted ALOHA

P s Cons













ygives







0 [ 0 0 ]



= p (1-p)N-1 (1-p)N-1

= p (1-p)2(N-1)


= p (1 p)


= 1(2e) = 18








collision




6



collision detection














polldata




slaves

data



T

(nothing



data

to send)T







7






Link Layer














1A-2F-BB-76-09-AD


= adapter

58-23-D7-FA-20-B0

0C-C4-11-6F-E3-98

71-65-F7-2B-08-53


LAN Address (more)










137196778


pp gsome LAN nodes


1A-2F-BB-76-09-AD

58-23-D7-FA-20-B0

0C-C4-11-6F-E3-98

71-65-F7-2B-08-53

LAN

137196723 137196714

137196788

8



















223111

223112223114 223129

223121A DHCP server


223113223122

223132223131

2231327

BE arriving DHCP



clientDHCP discover




time





1A-23-F9-CD-06-9BE6-E9-00-17-BB-4B

111111111111

A74-29-9C-E8-FF-55

222222222221

88-B2-2F-54-1A-0F



R

222222222220111111111110

CC-49-DE-D0-AB-7D

111111111112B

222222222222

49-BD-D2-C7-56-2A






R

1A-23-F9-CD-06-9B

222222222220111111111110

E6-E9-00-17-BB-4B

CC-49-DE-D0-AB-7D

111111111112

111111111111

A74-29-9C-E8-FF-55

222222222221

88-B2-2F-54-1A-0F

B222222222222

49-BD-D2-C7-56-2A

9

Link Layer








p p p p p






switch

















10


















CSMACD efficiency


efficiency 1=




transprop ttff y

51+





linkphysical


100BASE-TX

100BASE-T4




Manchester encoding




Link Layer





11





twisted pair

hub



l k h f f







A

BCrsquo

1 2 345

6






ArsquoBrsquo

C


45

Switch Table


A

BCrsquo

1 2 345

6





ArsquoBrsquo

C


45




d i i LAN

A

BCrsquo

1 2 345

6

A Arsquo

Source ADest Arsquo



ArsquoBrsquo

C

45





then






12


A

BCrsquo

1 2 345

6

A Arsquo

Source ADest Arsquo



ArsquoBrsquo

C

45



Arsquo A


Arsquo 4 60

selective send



A

B

S1

C DF

S2

S4

S3

I


B


C D

E HI

G


A

B

S1

C DF

S2

S4

S3

I

12



B C D

E HI

G


to externalnetwork

router

mail server

web server


IP subnet






Summary comparison


traffic isolation

no yes yes



optimal routing

no yes no

cut through

yes no yes

13

Link Layer



















PPP Data Frame




PPP Data Frame



14






Byte Stuffing









Link Layer














k d k





15






gateway






ATM and MPLS








Q f d



ATM architecture

physical

ATM

AAL

physical

ATM

AAL

physical

ATM

physical

ATM

d d ti h it h




physical layer






ATMnetwork

IPnetwork




16






physical

ATM

AAL

physical

ATM

AAL

physical

ATM

physical

ATM





AAL PDU

ATM cell

User data



NetworkArchitecture


Congestionfeedback

Guarantees


Internet

ATM

ATM

ATM

ATM

best effort

CBR

VBR

ABR

UBR

none


no

yes

yes

no

no

no

yes

yes

yes

yes

no

yes

yes

no

no


no















y p

Cell header

Cell format

17










medium being used


ATM Physical Layer


bit synchronization







ATM


ATMnetwork

EthernetLANs

EthernetLANs

IP-Over-ATM

AALATMphyphy

EthIP

ATM

ATMphy

apptransport

IPAALATMphy

apptransport

IPEthphy


ATMphy

p y






18

IP-Over-ATM


TM dd

ATMnetwork



EthernetLANs





g p


label Exp S TTL

20 3 1 5









10 6 A 112 9 D 0


10 A 012 D 08 A 1



R1R2

DR3R4

R50

100

A

R6


6 - A 0

1


8 6 A 0

0











3













CRC ExampleWant





R = remainder[ ]D2r

G

Link Layer




















4




average rate RM




4 simple



Random Access








1 3 4 1 3 4

6-slotframe





freq

uenc

y ba

nds

FDM cable







Slotted ALOHA







5

Slotted ALOHA

P s Cons













ygives







0 [ 0 0 ]



= p (1-p)N-1 (1-p)N-1

= p (1-p)2(N-1)


= p (1 p)


= 1(2e) = 18








collision




6



collision detection














polldata




slaves

data



T

(nothing



data

to send)T







7






Link Layer














1A-2F-BB-76-09-AD


= adapter

58-23-D7-FA-20-B0

0C-C4-11-6F-E3-98

71-65-F7-2B-08-53


LAN Address (more)










137196778


pp gsome LAN nodes


1A-2F-BB-76-09-AD

58-23-D7-FA-20-B0

0C-C4-11-6F-E3-98

71-65-F7-2B-08-53

LAN

137196723 137196714

137196788

8



















223111

223112223114 223129

223121A DHCP server


223113223122

223132223131

2231327

BE arriving DHCP



clientDHCP discover




time





1A-23-F9-CD-06-9BE6-E9-00-17-BB-4B

111111111111

A74-29-9C-E8-FF-55

222222222221

88-B2-2F-54-1A-0F



R

222222222220111111111110

CC-49-DE-D0-AB-7D

111111111112B

222222222222

49-BD-D2-C7-56-2A






R

1A-23-F9-CD-06-9B

222222222220111111111110

E6-E9-00-17-BB-4B

CC-49-DE-D0-AB-7D

111111111112

111111111111

A74-29-9C-E8-FF-55

222222222221

88-B2-2F-54-1A-0F

B222222222222

49-BD-D2-C7-56-2A

9

Link Layer








p p p p p






switch

















10


















CSMACD efficiency


efficiency 1=




transprop ttff y

51+





linkphysical


100BASE-TX

100BASE-T4




Manchester encoding




Link Layer





11





twisted pair

hub



l k h f f







A

BCrsquo

1 2 345

6






ArsquoBrsquo

C


45

Switch Table


A

BCrsquo

1 2 345

6





ArsquoBrsquo

C


45




d i i LAN

A

BCrsquo

1 2 345

6

A Arsquo

Source ADest Arsquo



ArsquoBrsquo

C

45





then






12


A

BCrsquo

1 2 345

6

A Arsquo

Source ADest Arsquo



ArsquoBrsquo

C

45



Arsquo A


Arsquo 4 60

selective send



A

B

S1

C DF

S2

S4

S3

I


B


C D

E HI

G


A

B

S1

C DF

S2

S4

S3

I

12



B C D

E HI

G


to externalnetwork

router

mail server

web server


IP subnet






Summary comparison


traffic isolation

no yes yes



optimal routing

no yes no

cut through

yes no yes

13

Link Layer



















PPP Data Frame




PPP Data Frame



14






Byte Stuffing









Link Layer














k d k





15






gateway






ATM and MPLS








Q f d



ATM architecture

physical

ATM

AAL

physical

ATM

AAL

physical

ATM

physical

ATM

d d ti h it h




physical layer






ATMnetwork

IPnetwork




16






physical

ATM

AAL

physical

ATM

AAL

physical

ATM

physical

ATM





AAL PDU

ATM cell

User data



NetworkArchitecture


Congestionfeedback

Guarantees


Internet

ATM

ATM

ATM

ATM

best effort

CBR

VBR

ABR

UBR

none


no

yes

yes

no

no

no

yes

yes

yes

yes

no

yes

yes

no

no


no















y p

Cell header

Cell format

17










medium being used


ATM Physical Layer


bit synchronization







ATM


ATMnetwork

EthernetLANs

EthernetLANs

IP-Over-ATM

AALATMphyphy

EthIP

ATM

ATMphy

apptransport

IPAALATMphy

apptransport

IPEthphy


ATMphy

p y






18

IP-Over-ATM


TM dd

ATMnetwork



EthernetLANs





g p


label Exp S TTL

20 3 1 5









10 6 A 112 9 D 0


10 A 012 D 08 A 1



R1R2

DR3R4

R50

100

A

R6


6 - A 0

1


8 6 A 0

0











4




average rate RM




4 simple



Random Access








1 3 4 1 3 4

6-slotframe





freq

uenc

y ba

nds

FDM cable







Slotted ALOHA







5

Slotted ALOHA

P s Cons













ygives







0 [ 0 0 ]



= p (1-p)N-1 (1-p)N-1

= p (1-p)2(N-1)


= p (1 p)


= 1(2e) = 18








collision




6



collision detection














polldata




slaves

data



T

(nothing



data

to send)T







7






Link Layer














1A-2F-BB-76-09-AD


= adapter

58-23-D7-FA-20-B0

0C-C4-11-6F-E3-98

71-65-F7-2B-08-53


LAN Address (more)










137196778


pp gsome LAN nodes


1A-2F-BB-76-09-AD

58-23-D7-FA-20-B0

0C-C4-11-6F-E3-98

71-65-F7-2B-08-53

LAN

137196723 137196714

137196788

8



















223111

223112223114 223129

223121A DHCP server


223113223122

223132223131

2231327

BE arriving DHCP



clientDHCP discover




time





1A-23-F9-CD-06-9BE6-E9-00-17-BB-4B

111111111111

A74-29-9C-E8-FF-55

222222222221

88-B2-2F-54-1A-0F



R

222222222220111111111110

CC-49-DE-D0-AB-7D

111111111112B

222222222222

49-BD-D2-C7-56-2A






R

1A-23-F9-CD-06-9B

222222222220111111111110

E6-E9-00-17-BB-4B

CC-49-DE-D0-AB-7D

111111111112

111111111111

A74-29-9C-E8-FF-55

222222222221

88-B2-2F-54-1A-0F

B222222222222

49-BD-D2-C7-56-2A

9

Link Layer








p p p p p






switch

















10


















CSMACD efficiency


efficiency 1=




transprop ttff y

51+





linkphysical


100BASE-TX

100BASE-T4




Manchester encoding




Link Layer





11





twisted pair

hub



l k h f f







A

BCrsquo

1 2 345

6






ArsquoBrsquo

C


45

Switch Table


A

BCrsquo

1 2 345

6





ArsquoBrsquo

C


45




d i i LAN

A

BCrsquo

1 2 345

6

A Arsquo

Source ADest Arsquo



ArsquoBrsquo

C

45





then






12


A

BCrsquo

1 2 345

6

A Arsquo

Source ADest Arsquo



ArsquoBrsquo

C

45



Arsquo A


Arsquo 4 60

selective send



A

B

S1

C DF

S2

S4

S3

I


B


C D

E HI

G


A

B

S1

C DF

S2

S4

S3

I

12



B C D

E HI

G


to externalnetwork

router

mail server

web server


IP subnet






Summary comparison


traffic isolation

no yes yes



optimal routing

no yes no

cut through

yes no yes

13

Link Layer



















PPP Data Frame




PPP Data Frame



14






Byte Stuffing









Link Layer














k d k





15






gateway






ATM and MPLS








Q f d



ATM architecture

physical

ATM

AAL

physical

ATM

AAL

physical

ATM

physical

ATM

d d ti h it h




physical layer






ATMnetwork

IPnetwork




16






physical

ATM

AAL

physical

ATM

AAL

physical

ATM

physical

ATM





AAL PDU

ATM cell

User data



NetworkArchitecture


Congestionfeedback

Guarantees


Internet

ATM

ATM

ATM

ATM

best effort

CBR

VBR

ABR

UBR

none


no

yes

yes

no

no

no

yes

yes

yes

yes

no

yes

yes

no

no


no















y p

Cell header

Cell format

17










medium being used


ATM Physical Layer


bit synchronization







ATM


ATMnetwork

EthernetLANs

EthernetLANs

IP-Over-ATM

AALATMphyphy

EthIP

ATM

ATMphy

apptransport

IPAALATMphy

apptransport

IPEthphy


ATMphy

p y






18

IP-Over-ATM


TM dd

ATMnetwork



EthernetLANs





g p


label Exp S TTL

20 3 1 5









10 6 A 112 9 D 0


10 A 012 D 08 A 1



R1R2

DR3R4

R50

100

A

R6


6 - A 0

1


8 6 A 0

0











5

Slotted ALOHA

P s Cons













ygives







0 [ 0 0 ]



= p (1-p)N-1 (1-p)N-1

= p (1-p)2(N-1)


= p (1 p)


= 1(2e) = 18








collision




6



collision detection














polldata




slaves

data



T

(nothing



data

to send)T







7






Link Layer














1A-2F-BB-76-09-AD


= adapter

58-23-D7-FA-20-B0

0C-C4-11-6F-E3-98

71-65-F7-2B-08-53


LAN Address (more)










137196778


pp gsome LAN nodes


1A-2F-BB-76-09-AD

58-23-D7-FA-20-B0

0C-C4-11-6F-E3-98

71-65-F7-2B-08-53

LAN

137196723 137196714

137196788

8



















223111

223112223114 223129

223121A DHCP server


223113223122

223132223131

2231327

BE arriving DHCP



clientDHCP discover




time





1A-23-F9-CD-06-9BE6-E9-00-17-BB-4B

111111111111

A74-29-9C-E8-FF-55

222222222221

88-B2-2F-54-1A-0F



R

222222222220111111111110

CC-49-DE-D0-AB-7D

111111111112B

222222222222

49-BD-D2-C7-56-2A






R

1A-23-F9-CD-06-9B

222222222220111111111110

E6-E9-00-17-BB-4B

CC-49-DE-D0-AB-7D

111111111112

111111111111

A74-29-9C-E8-FF-55

222222222221

88-B2-2F-54-1A-0F

B222222222222

49-BD-D2-C7-56-2A

9

Link Layer








p p p p p






switch

















10


















CSMACD efficiency


efficiency 1=




transprop ttff y

51+





linkphysical


100BASE-TX

100BASE-T4




Manchester encoding




Link Layer





11





twisted pair

hub



l k h f f







A

BCrsquo

1 2 345

6






ArsquoBrsquo

C


45

Switch Table


A

BCrsquo

1 2 345

6





ArsquoBrsquo

C


45




d i i LAN

A

BCrsquo

1 2 345

6

A Arsquo

Source ADest Arsquo



ArsquoBrsquo

C

45





then






12


A

BCrsquo

1 2 345

6

A Arsquo

Source ADest Arsquo



ArsquoBrsquo

C

45



Arsquo A


Arsquo 4 60

selective send



A

B

S1

C DF

S2

S4

S3

I


B


C D

E HI

G


A

B

S1

C DF

S2

S4

S3

I

12



B C D

E HI

G


to externalnetwork

router

mail server

web server


IP subnet






Summary comparison


traffic isolation

no yes yes



optimal routing

no yes no

cut through

yes no yes

13

Link Layer



















PPP Data Frame




PPP Data Frame



14






Byte Stuffing









Link Layer














k d k





15






gateway






ATM and MPLS








Q f d



ATM architecture

physical

ATM

AAL

physical

ATM

AAL

physical

ATM

physical

ATM

d d ti h it h




physical layer






ATMnetwork

IPnetwork




16






physical

ATM

AAL

physical

ATM

AAL

physical

ATM

physical

ATM





AAL PDU

ATM cell

User data



NetworkArchitecture


Congestionfeedback

Guarantees


Internet

ATM

ATM

ATM

ATM

best effort

CBR

VBR

ABR

UBR

none


no

yes

yes

no

no

no

yes

yes

yes

yes

no

yes

yes

no

no


no















y p

Cell header

Cell format

17










medium being used


ATM Physical Layer


bit synchronization







ATM


ATMnetwork

EthernetLANs

EthernetLANs

IP-Over-ATM

AALATMphyphy

EthIP

ATM

ATMphy

apptransport

IPAALATMphy

apptransport

IPEthphy


ATMphy

p y






18

IP-Over-ATM


TM dd

ATMnetwork



EthernetLANs





g p


label Exp S TTL

20 3 1 5









10 6 A 112 9 D 0


10 A 012 D 08 A 1



R1R2

DR3R4

R50

100

A

R6


6 - A 0

1


8 6 A 0

0











6



collision detection














polldata




slaves

data



T

(nothing



data

to send)T







7






Link Layer














1A-2F-BB-76-09-AD


= adapter

58-23-D7-FA-20-B0

0C-C4-11-6F-E3-98

71-65-F7-2B-08-53


LAN Address (more)










137196778


pp gsome LAN nodes


1A-2F-BB-76-09-AD

58-23-D7-FA-20-B0

0C-C4-11-6F-E3-98

71-65-F7-2B-08-53

LAN

137196723 137196714

137196788

8



















223111

223112223114 223129

223121A DHCP server


223113223122

223132223131

2231327

BE arriving DHCP



clientDHCP discover




time





1A-23-F9-CD-06-9BE6-E9-00-17-BB-4B

111111111111

A74-29-9C-E8-FF-55

222222222221

88-B2-2F-54-1A-0F



R

222222222220111111111110

CC-49-DE-D0-AB-7D

111111111112B

222222222222

49-BD-D2-C7-56-2A






R

1A-23-F9-CD-06-9B

222222222220111111111110

E6-E9-00-17-BB-4B

CC-49-DE-D0-AB-7D

111111111112

111111111111

A74-29-9C-E8-FF-55

222222222221

88-B2-2F-54-1A-0F

B222222222222

49-BD-D2-C7-56-2A

9

Link Layer








p p p p p






switch

















10


















CSMACD efficiency


efficiency 1=




transprop ttff y

51+





linkphysical


100BASE-TX

100BASE-T4




Manchester encoding




Link Layer





11





twisted pair

hub



l k h f f







A

BCrsquo

1 2 345

6






ArsquoBrsquo

C


45

Switch Table


A

BCrsquo

1 2 345

6





ArsquoBrsquo

C


45




d i i LAN

A

BCrsquo

1 2 345

6

A Arsquo

Source ADest Arsquo



ArsquoBrsquo

C

45





then






12


A

BCrsquo

1 2 345

6

A Arsquo

Source ADest Arsquo



ArsquoBrsquo

C

45



Arsquo A


Arsquo 4 60

selective send



A

B

S1

C DF

S2

S4

S3

I


B


C D

E HI

G


A

B

S1

C DF

S2

S4

S3

I

12



B C D

E HI

G


to externalnetwork

router

mail server

web server


IP subnet






Summary comparison


traffic isolation

no yes yes



optimal routing

no yes no

cut through

yes no yes

13

Link Layer



















PPP Data Frame




PPP Data Frame



14






Byte Stuffing









Link Layer














k d k





15






gateway






ATM and MPLS








Q f d



ATM architecture

physical

ATM

AAL

physical

ATM

AAL

physical

ATM

physical

ATM

d d ti h it h




physical layer






ATMnetwork

IPnetwork




16






physical

ATM

AAL

physical

ATM

AAL

physical

ATM

physical

ATM





AAL PDU

ATM cell

User data



NetworkArchitecture


Congestionfeedback

Guarantees


Internet

ATM

ATM

ATM

ATM

best effort

CBR

VBR

ABR

UBR

none


no

yes

yes

no

no

no

yes

yes

yes

yes

no

yes

yes

no

no


no















y p

Cell header

Cell format

17










medium being used


ATM Physical Layer


bit synchronization







ATM


ATMnetwork

EthernetLANs

EthernetLANs

IP-Over-ATM

AALATMphyphy

EthIP

ATM

ATMphy

apptransport

IPAALATMphy

apptransport

IPEthphy


ATMphy

p y






18

IP-Over-ATM


TM dd

ATMnetwork



EthernetLANs





g p


label Exp S TTL

20 3 1 5









10 6 A 112 9 D 0


10 A 012 D 08 A 1



R1R2

DR3R4

R50

100

A

R6


6 - A 0

1


8 6 A 0

0











7






Link Layer














1A-2F-BB-76-09-AD


= adapter

58-23-D7-FA-20-B0

0C-C4-11-6F-E3-98

71-65-F7-2B-08-53


LAN Address (more)










137196778


pp gsome LAN nodes


1A-2F-BB-76-09-AD

58-23-D7-FA-20-B0

0C-C4-11-6F-E3-98

71-65-F7-2B-08-53

LAN

137196723 137196714

137196788

8



















223111

223112223114 223129

223121A DHCP server


223113223122

223132223131

2231327

BE arriving DHCP



clientDHCP discover




time





1A-23-F9-CD-06-9BE6-E9-00-17-BB-4B

111111111111

A74-29-9C-E8-FF-55

222222222221

88-B2-2F-54-1A-0F



R

222222222220111111111110

CC-49-DE-D0-AB-7D

111111111112B

222222222222

49-BD-D2-C7-56-2A






R

1A-23-F9-CD-06-9B

222222222220111111111110

E6-E9-00-17-BB-4B

CC-49-DE-D0-AB-7D

111111111112

111111111111

A74-29-9C-E8-FF-55

222222222221

88-B2-2F-54-1A-0F

B222222222222

49-BD-D2-C7-56-2A

9

Link Layer








p p p p p






switch

















10


















CSMACD efficiency


efficiency 1=




transprop ttff y

51+





linkphysical


100BASE-TX

100BASE-T4




Manchester encoding




Link Layer





11





twisted pair

hub



l k h f f







A

BCrsquo

1 2 345

6






ArsquoBrsquo

C


45

Switch Table


A

BCrsquo

1 2 345

6





ArsquoBrsquo

C


45




d i i LAN

A

BCrsquo

1 2 345

6

A Arsquo

Source ADest Arsquo



ArsquoBrsquo

C

45





then






12


A

BCrsquo

1 2 345

6

A Arsquo

Source ADest Arsquo



ArsquoBrsquo

C

45



Arsquo A


Arsquo 4 60

selective send



A

B

S1

C DF

S2

S4

S3

I


B


C D

E HI

G


A

B

S1

C DF

S2

S4

S3

I

12



B C D

E HI

G


to externalnetwork

router

mail server

web server


IP subnet






Summary comparison


traffic isolation

no yes yes



optimal routing

no yes no

cut through

yes no yes

13

Link Layer



















PPP Data Frame




PPP Data Frame



14






Byte Stuffing









Link Layer














k d k





15






gateway






ATM and MPLS








Q f d



ATM architecture

physical

ATM

AAL

physical

ATM

AAL

physical

ATM

physical

ATM

d d ti h it h




physical layer






ATMnetwork

IPnetwork




16






physical

ATM

AAL

physical

ATM

AAL

physical

ATM

physical

ATM





AAL PDU

ATM cell

User data



NetworkArchitecture


Congestionfeedback

Guarantees


Internet

ATM

ATM

ATM

ATM

best effort

CBR

VBR

ABR

UBR

none


no

yes

yes

no

no

no

yes

yes

yes

yes

no

yes

yes

no

no


no















y p

Cell header

Cell format

17










medium being used


ATM Physical Layer


bit synchronization







ATM


ATMnetwork

EthernetLANs

EthernetLANs

IP-Over-ATM

AALATMphyphy

EthIP

ATM

ATMphy

apptransport

IPAALATMphy

apptransport

IPEthphy


ATMphy

p y






18

IP-Over-ATM


TM dd

ATMnetwork



EthernetLANs





g p


label Exp S TTL

20 3 1 5









10 6 A 112 9 D 0


10 A 012 D 08 A 1



R1R2

DR3R4

R50

100

A

R6


6 - A 0

1


8 6 A 0

0











8



















223111

223112223114 223129

223121A DHCP server


223113223122

223132223131

2231327

BE arriving DHCP



clientDHCP discover




time





1A-23-F9-CD-06-9BE6-E9-00-17-BB-4B

111111111111

A74-29-9C-E8-FF-55

222222222221

88-B2-2F-54-1A-0F



R

222222222220111111111110

CC-49-DE-D0-AB-7D

111111111112B

222222222222

49-BD-D2-C7-56-2A






R

1A-23-F9-CD-06-9B

222222222220111111111110

E6-E9-00-17-BB-4B

CC-49-DE-D0-AB-7D

111111111112

111111111111

A74-29-9C-E8-FF-55

222222222221

88-B2-2F-54-1A-0F

B222222222222

49-BD-D2-C7-56-2A

9

Link Layer








p p p p p






switch

















10


















CSMACD efficiency


efficiency 1=




transprop ttff y

51+





linkphysical


100BASE-TX

100BASE-T4




Manchester encoding




Link Layer





11





twisted pair

hub



l k h f f







A

BCrsquo

1 2 345

6






ArsquoBrsquo

C


45

Switch Table


A

BCrsquo

1 2 345

6





ArsquoBrsquo

C


45




d i i LAN

A

BCrsquo

1 2 345

6

A Arsquo

Source ADest Arsquo



ArsquoBrsquo

C

45





then






12


A

BCrsquo

1 2 345

6

A Arsquo

Source ADest Arsquo



ArsquoBrsquo

C

45



Arsquo A


Arsquo 4 60

selective send



A

B

S1

C DF

S2

S4

S3

I


B


C D

E HI

G


A

B

S1

C DF

S2

S4

S3

I

12



B C D

E HI

G


to externalnetwork

router

mail server

web server


IP subnet






Summary comparison


traffic isolation

no yes yes



optimal routing

no yes no

cut through

yes no yes

13

Link Layer



















PPP Data Frame




PPP Data Frame



14






Byte Stuffing









Link Layer














k d k





15






gateway






ATM and MPLS








Q f d



ATM architecture

physical

ATM

AAL

physical

ATM

AAL

physical

ATM

physical

ATM

d d ti h it h




physical layer






ATMnetwork

IPnetwork




16






physical

ATM

AAL

physical

ATM

AAL

physical

ATM

physical

ATM





AAL PDU

ATM cell

User data



NetworkArchitecture


Congestionfeedback

Guarantees


Internet

ATM

ATM

ATM

ATM

best effort

CBR

VBR

ABR

UBR

none


no

yes

yes

no

no

no

yes

yes

yes

yes

no

yes

yes

no

no


no















y p

Cell header

Cell format

17










medium being used


ATM Physical Layer


bit synchronization







ATM


ATMnetwork

EthernetLANs

EthernetLANs

IP-Over-ATM

AALATMphyphy

EthIP

ATM

ATMphy

apptransport

IPAALATMphy

apptransport

IPEthphy


ATMphy

p y






18

IP-Over-ATM


TM dd

ATMnetwork



EthernetLANs





g p


label Exp S TTL

20 3 1 5









10 6 A 112 9 D 0


10 A 012 D 08 A 1



R1R2

DR3R4

R50

100

A

R6


6 - A 0

1


8 6 A 0

0











9

Link Layer








p p p p p






switch

















10


















CSMACD efficiency


efficiency 1=




transprop ttff y

51+





linkphysical


100BASE-TX

100BASE-T4




Manchester encoding




Link Layer





11





twisted pair

hub



l k h f f







A

BCrsquo

1 2 345

6






ArsquoBrsquo

C


45

Switch Table


A

BCrsquo

1 2 345

6





ArsquoBrsquo

C


45




d i i LAN

A

BCrsquo

1 2 345

6

A Arsquo

Source ADest Arsquo



ArsquoBrsquo

C

45





then






12


A

BCrsquo

1 2 345

6

A Arsquo

Source ADest Arsquo



ArsquoBrsquo

C

45



Arsquo A


Arsquo 4 60

selective send



A

B

S1

C DF

S2

S4

S3

I


B


C D

E HI

G


A

B

S1

C DF

S2

S4

S3

I

12



B C D

E HI

G


to externalnetwork

router

mail server

web server


IP subnet






Summary comparison


traffic isolation

no yes yes



optimal routing

no yes no

cut through

yes no yes

13

Link Layer



















PPP Data Frame




PPP Data Frame



14






Byte Stuffing









Link Layer














k d k





15






gateway






ATM and MPLS








Q f d



ATM architecture

physical

ATM

AAL

physical

ATM

AAL

physical

ATM

physical

ATM

d d ti h it h




physical layer






ATMnetwork

IPnetwork




16






physical

ATM

AAL

physical

ATM

AAL

physical

ATM

physical

ATM





AAL PDU

ATM cell

User data



NetworkArchitecture


Congestionfeedback

Guarantees


Internet

ATM

ATM

ATM

ATM

best effort

CBR

VBR

ABR

UBR

none


no

yes

yes

no

no

no

yes

yes

yes

yes

no

yes

yes

no

no


no















y p

Cell header

Cell format

17










medium being used


ATM Physical Layer


bit synchronization







ATM


ATMnetwork

EthernetLANs

EthernetLANs

IP-Over-ATM

AALATMphyphy

EthIP

ATM

ATMphy

apptransport

IPAALATMphy

apptransport

IPEthphy


ATMphy

p y






18

IP-Over-ATM


TM dd

ATMnetwork



EthernetLANs





g p


label Exp S TTL

20 3 1 5









10 6 A 112 9 D 0


10 A 012 D 08 A 1



R1R2

DR3R4

R50

100

A

R6


6 - A 0

1


8 6 A 0

0











10


















CSMACD efficiency


efficiency 1=




transprop ttff y

51+





linkphysical


100BASE-TX

100BASE-T4




Manchester encoding




Link Layer





11





twisted pair

hub



l k h f f







A

BCrsquo

1 2 345

6






ArsquoBrsquo

C


45

Switch Table


A

BCrsquo

1 2 345

6





ArsquoBrsquo

C


45




d i i LAN

A

BCrsquo

1 2 345

6

A Arsquo

Source ADest Arsquo



ArsquoBrsquo

C

45





then






12


A

BCrsquo

1 2 345

6

A Arsquo

Source ADest Arsquo



ArsquoBrsquo

C

45



Arsquo A


Arsquo 4 60

selective send



A

B

S1

C DF

S2

S4

S3

I


B


C D

E HI

G


A

B

S1

C DF

S2

S4

S3

I

12



B C D

E HI

G


to externalnetwork

router

mail server

web server


IP subnet






Summary comparison


traffic isolation

no yes yes



optimal routing

no yes no

cut through

yes no yes

13

Link Layer



















PPP Data Frame




PPP Data Frame



14






Byte Stuffing









Link Layer














k d k





15






gateway






ATM and MPLS








Q f d



ATM architecture

physical

ATM

AAL

physical

ATM

AAL

physical

ATM

physical

ATM

d d ti h it h




physical layer






ATMnetwork

IPnetwork




16






physical

ATM

AAL

physical

ATM

AAL

physical

ATM

physical

ATM





AAL PDU

ATM cell

User data



NetworkArchitecture


Congestionfeedback

Guarantees


Internet

ATM

ATM

ATM

ATM

best effort

CBR

VBR

ABR

UBR

none


no

yes

yes

no

no

no

yes

yes

yes

yes

no

yes

yes

no

no


no















y p

Cell header

Cell format

17










medium being used


ATM Physical Layer


bit synchronization







ATM


ATMnetwork

EthernetLANs

EthernetLANs

IP-Over-ATM

AALATMphyphy

EthIP

ATM

ATMphy

apptransport

IPAALATMphy

apptransport

IPEthphy


ATMphy

p y






18

IP-Over-ATM


TM dd

ATMnetwork



EthernetLANs





g p


label Exp S TTL

20 3 1 5









10 6 A 112 9 D 0


10 A 012 D 08 A 1



R1R2

DR3R4

R50

100

A

R6


6 - A 0

1


8 6 A 0

0











11





twisted pair

hub



l k h f f







A

BCrsquo

1 2 345

6






ArsquoBrsquo

C


45

Switch Table


A

BCrsquo

1 2 345

6





ArsquoBrsquo

C


45




d i i LAN

A

BCrsquo

1 2 345

6

A Arsquo

Source ADest Arsquo



ArsquoBrsquo

C

45





then






12


A

BCrsquo

1 2 345

6

A Arsquo

Source ADest Arsquo



ArsquoBrsquo

C

45



Arsquo A


Arsquo 4 60

selective send



A

B

S1

C DF

S2

S4

S3

I


B


C D

E HI

G


A

B

S1

C DF

S2

S4

S3

I

12



B C D

E HI

G


to externalnetwork

router

mail server

web server


IP subnet






Summary comparison


traffic isolation

no yes yes



optimal routing

no yes no

cut through

yes no yes

13

Link Layer



















PPP Data Frame




PPP Data Frame



14






Byte Stuffing









Link Layer














k d k





15






gateway






ATM and MPLS








Q f d



ATM architecture

physical

ATM

AAL

physical

ATM

AAL

physical

ATM

physical

ATM

d d ti h it h




physical layer






ATMnetwork

IPnetwork




16






physical

ATM

AAL

physical

ATM

AAL

physical

ATM

physical

ATM





AAL PDU

ATM cell

User data



NetworkArchitecture


Congestionfeedback

Guarantees


Internet

ATM

ATM

ATM

ATM

best effort

CBR

VBR

ABR

UBR

none


no

yes

yes

no

no

no

yes

yes

yes

yes

no

yes

yes

no

no


no















y p

Cell header

Cell format

17










medium being used


ATM Physical Layer


bit synchronization







ATM


ATMnetwork

EthernetLANs

EthernetLANs

IP-Over-ATM

AALATMphyphy

EthIP

ATM

ATMphy

apptransport

IPAALATMphy

apptransport

IPEthphy


ATMphy

p y






18

IP-Over-ATM


TM dd

ATMnetwork



EthernetLANs





g p


label Exp S TTL

20 3 1 5









10 6 A 112 9 D 0


10 A 012 D 08 A 1



R1R2

DR3R4

R50

100

A

R6


6 - A 0

1


8 6 A 0

0











12


A

BCrsquo

1 2 345

6

A Arsquo

Source ADest Arsquo



ArsquoBrsquo

C

45



Arsquo A


Arsquo 4 60

selective send



A

B

S1

C DF

S2

S4

S3

I


B


C D

E HI

G


A

B

S1

C DF

S2

S4

S3

I

12



B C D

E HI

G


to externalnetwork

router

mail server

web server


IP subnet






Summary comparison


traffic isolation

no yes yes



optimal routing

no yes no

cut through

yes no yes

13

Link Layer



















PPP Data Frame




PPP Data Frame



14






Byte Stuffing









Link Layer














k d k





15






gateway






ATM and MPLS








Q f d



ATM architecture

physical

ATM

AAL

physical

ATM

AAL

physical

ATM

physical

ATM

d d ti h it h




physical layer






ATMnetwork

IPnetwork




16






physical

ATM

AAL

physical

ATM

AAL

physical

ATM

physical

ATM





AAL PDU

ATM cell

User data



NetworkArchitecture


Congestionfeedback

Guarantees


Internet

ATM

ATM

ATM

ATM

best effort

CBR

VBR

ABR

UBR

none


no

yes

yes

no

no

no

yes

yes

yes

yes

no

yes

yes

no

no


no















y p

Cell header

Cell format

17










medium being used


ATM Physical Layer


bit synchronization







ATM


ATMnetwork

EthernetLANs

EthernetLANs

IP-Over-ATM

AALATMphyphy

EthIP

ATM

ATMphy

apptransport

IPAALATMphy

apptransport

IPEthphy


ATMphy

p y






18

IP-Over-ATM


TM dd

ATMnetwork



EthernetLANs





g p


label Exp S TTL

20 3 1 5









10 6 A 112 9 D 0


10 A 012 D 08 A 1



R1R2

DR3R4

R50

100

A

R6


6 - A 0

1


8 6 A 0

0











13

Link Layer



















PPP Data Frame




PPP Data Frame



14






Byte Stuffing









Link Layer














k d k





15






gateway






ATM and MPLS








Q f d



ATM architecture

physical

ATM

AAL

physical

ATM

AAL

physical

ATM

physical

ATM

d d ti h it h




physical layer






ATMnetwork

IPnetwork




16






physical

ATM

AAL

physical

ATM

AAL

physical

ATM

physical

ATM





AAL PDU

ATM cell

User data



NetworkArchitecture


Congestionfeedback

Guarantees


Internet

ATM

ATM

ATM

ATM

best effort

CBR

VBR

ABR

UBR

none


no

yes

yes

no

no

no

yes

yes

yes

yes

no

yes

yes

no

no


no















y p

Cell header

Cell format

17










medium being used


ATM Physical Layer


bit synchronization







ATM


ATMnetwork

EthernetLANs

EthernetLANs

IP-Over-ATM

AALATMphyphy

EthIP

ATM

ATMphy

apptransport

IPAALATMphy

apptransport

IPEthphy


ATMphy

p y






18

IP-Over-ATM


TM dd

ATMnetwork



EthernetLANs





g p


label Exp S TTL

20 3 1 5









10 6 A 112 9 D 0


10 A 012 D 08 A 1



R1R2

DR3R4

R50

100

A

R6


6 - A 0

1


8 6 A 0

0











14






Byte Stuffing









Link Layer














k d k





15






gateway






ATM and MPLS








Q f d



ATM architecture

physical

ATM

AAL

physical

ATM

AAL

physical

ATM

physical

ATM

d d ti h it h




physical layer






ATMnetwork

IPnetwork




16






physical

ATM

AAL

physical

ATM

AAL

physical

ATM

physical

ATM





AAL PDU

ATM cell

User data



NetworkArchitecture


Congestionfeedback

Guarantees


Internet

ATM

ATM

ATM

ATM

best effort

CBR

VBR

ABR

UBR

none


no

yes

yes

no

no

no

yes

yes

yes

yes

no

yes

yes

no

no


no















y p

Cell header

Cell format

17










medium being used


ATM Physical Layer


bit synchronization







ATM


ATMnetwork

EthernetLANs

EthernetLANs

IP-Over-ATM

AALATMphyphy

EthIP

ATM

ATMphy

apptransport

IPAALATMphy

apptransport

IPEthphy


ATMphy

p y






18

IP-Over-ATM


TM dd

ATMnetwork



EthernetLANs





g p


label Exp S TTL

20 3 1 5









10 6 A 112 9 D 0


10 A 012 D 08 A 1



R1R2

DR3R4

R50

100

A

R6


6 - A 0

1


8 6 A 0

0











15






gateway






ATM and MPLS








Q f d



ATM architecture

physical

ATM

AAL

physical

ATM

AAL

physical

ATM

physical

ATM

d d ti h it h




physical layer






ATMnetwork

IPnetwork




16






physical

ATM

AAL

physical

ATM

AAL

physical

ATM

physical

ATM





AAL PDU

ATM cell

User data



NetworkArchitecture


Congestionfeedback

Guarantees


Internet

ATM

ATM

ATM

ATM

best effort

CBR

VBR

ABR

UBR

none


no

yes

yes

no

no

no

yes

yes

yes

yes

no

yes

yes

no

no


no















y p

Cell header

Cell format

17










medium being used


ATM Physical Layer


bit synchronization







ATM


ATMnetwork

EthernetLANs

EthernetLANs

IP-Over-ATM

AALATMphyphy

EthIP

ATM

ATMphy

apptransport

IPAALATMphy

apptransport

IPEthphy


ATMphy

p y






18

IP-Over-ATM


TM dd

ATMnetwork



EthernetLANs





g p


label Exp S TTL

20 3 1 5









10 6 A 112 9 D 0


10 A 012 D 08 A 1



R1R2

DR3R4

R50

100

A

R6


6 - A 0

1


8 6 A 0

0











16






physical

ATM

AAL

physical

ATM

AAL

physical

ATM

physical

ATM





AAL PDU

ATM cell

User data



NetworkArchitecture


Congestionfeedback

Guarantees


Internet

ATM

ATM

ATM

ATM

best effort

CBR

VBR

ABR

UBR

none


no

yes

yes

no

no

no

yes

yes

yes

yes

no

yes

yes

no

no


no















y p

Cell header

Cell format

17










medium being used


ATM Physical Layer


bit synchronization







ATM


ATMnetwork

EthernetLANs

EthernetLANs

IP-Over-ATM

AALATMphyphy

EthIP

ATM

ATMphy

apptransport

IPAALATMphy

apptransport

IPEthphy


ATMphy

p y






18

IP-Over-ATM


TM dd

ATMnetwork



EthernetLANs





g p


label Exp S TTL

20 3 1 5









10 6 A 112 9 D 0


10 A 012 D 08 A 1



R1R2

DR3R4

R50

100

A

R6


6 - A 0

1


8 6 A 0

0











17










medium being used


ATM Physical Layer


bit synchronization







ATM


ATMnetwork

EthernetLANs

EthernetLANs

IP-Over-ATM

AALATMphyphy

EthIP

ATM

ATMphy

apptransport

IPAALATMphy

apptransport

IPEthphy


ATMphy

p y






18

IP-Over-ATM


TM dd

ATMnetwork



EthernetLANs





g p


label Exp S TTL

20 3 1 5









10 6 A 112 9 D 0


10 A 012 D 08 A 1



R1R2

DR3R4

R50

100

A

R6


6 - A 0

1


8 6 A 0

0











18

IP-Over-ATM


TM dd

ATMnetwork



EthernetLANs





g p


label Exp S TTL

20 3 1 5









10 6 A 112 9 D 0


10 A 012 D 08 A 1



R1R2

DR3R4

R50

100

A

R6


6 - A 0

1


8 6 A 0

0











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Chapter 5: The Data Link Layer Link Layer and LANs · · 2017-08-281 Chapter 5 Link Layer and LANs 5: DataLink Layer 5-1 A note on the use of these ppt slides: We’re making these