Prepared byPrepared by

Fahad Al-Harbi 202817Fahad Al-Harbi 202817

Abdullah Al-Maimoni Abdullah Al-Maimoni 211967211967

ATM: Asynchronous ATM: Asynchronous Transfer ModeTransfer Mode

Why ATM networksWhy ATM networks?? Driven by the integration of services and performance Driven by the integration of services and performance

requirements of both telephony and data networkingrequirements of both telephony and data networking ““broadbandbroadband integrated service vision” ( integrated service vision” (B-ISDNB-ISDN))

Telephone networks support a single quality of Telephone networks support a single quality of serviceservice and is and is expensiveexpensive to boot to boot

Internet supports no quality of serviceInternet supports no quality of service but is but is flexible and cheapflexible and cheap

ATM networks are meant to support a ATM networks are meant to support a range of range of service qualities at a reasonable costservice qualities at a reasonable cost Intended to subsume both the telephone network and the Intended to subsume both the telephone network and the

InternetInternet

ATM ConceptsATM Concepts 1. Virtual circuits1. Virtual circuits2. Fixed-size packets (2. Fixed-size packets (cellscells): allowed fast h/w ): allowed fast h/w

switchingswitching3. Small packet size3. Small packet size4. Statistical multiplexing4. Statistical multiplexing5. Integrated services5. Integrated services6. Good management and traffic engineering features6. Good management and traffic engineering features7. Scalability in speed and network size7. Scalability in speed and network size

TogetherTogethercan carry can carry multiplemultiple types of traffic types of trafficwith end-to-end quality of servicewith end-to-end quality of service

ATM ApplicationsATM Applications ATM Deployments:ATM Deployments:

Frame Relay backbonesFrame Relay backbones Internet backbonesInternet backbones Aggregating Residential broadband networks Aggregating Residential broadband networks

(Cable, DSL, ISDN)(Cable, DSL, ISDN) Carrier infrastructures for the telephone and Carrier infrastructures for the telephone and

private-line networksprivate-line networks

Failed market tests of ATM:Failed market tests of ATM: ATM workgroup and campus networksATM workgroup and campus networks ATM enterprise network consolidationATM enterprise network consolidation End-to-end ATM…End-to-end ATM…

ATM vs Synchronous (Phone) ATM vs Synchronous (Phone) NetworksNetworks

Phone networks are Phone networks are synchronoussynchronous (periodic). (periodic). ATM = ATM = AsynchronousAsynchronous Transfer Mode Transfer Mode

Phone networks use Phone networks use circuit-switchingcircuit-switching.. ATM networks use “Packet” or “ATM networks use “Packet” or “cellcell” Switching” Switching

In phone networks, all rates are In phone networks, all rates are multiple of 64 kbpsmultiple of 64 kbps.. With ATM service, you can get With ATM service, you can get any rateany rate, and you can vary , and you can vary

your rate with time.your rate with time. With current phone networks, all high speed circuits With current phone networks, all high speed circuits

are are manually setupmanually setup. . ATM allows “dialing” any speed & ATM allows “dialing” any speed & rapid provisioningrapid provisioning

ATM vs Data Networks ATM vs Data Networks (Internet)(Internet)

ATM is “ATM is “virtual circuitvirtual circuit” based: the path (and optionally ” based: the path (and optionally resources on the path) is reserved before transmissionresources on the path) is reserved before transmission Internet Protocol (IP) is Internet Protocol (IP) is connectionlessconnectionless, and end-to-end , and end-to-end

resource reservations not possibleresource reservations not possible RSVP is a new signaling protocol in the InternetRSVP is a new signaling protocol in the Internet

ATM Cells: ATM Cells: Fixed/small sizeFixed/small size: tradeoff between voice/data: tradeoff between voice/data IP packets: IP packets: variable sizevariable size

ATM provides ATM provides QoS routingQoS routing coupled to signaling (PNNI) coupled to signaling (PNNI) Internet provides Internet provides “best-effort” routing“best-effort” routing (combination of (combination of

RIP/OSPF/IS-IS/BGP-4), aiming only for connectivityRIP/OSPF/IS-IS/BGP-4), aiming only for connectivity Addressing:Addressing:

ATM uses ATM uses 20-byte global NSAP addresses20-byte global NSAP addresses for signaling and for signaling and 32-bit locally-assigned labels32-bit locally-assigned labels in cells in cells

IP uses IP uses 32-bit global addresses32-bit global addresses in all packets in all packets ATM offers ATM offers sophisticated traffic managementsophisticated traffic management

TCP/IP: congestion control is TCP/IP: congestion control is packet-loss-basedpacket-loss-based

ATM InterfacesATM Interfaces

UNIUNI = User-Network Interface (Private & Public) = User-Network Interface (Private & Public) NNINNI = Network Node Interface (Private and Public) = Network Node Interface (Private and Public) B-ICIB-ICI = Broadband Inter-Carrier Interface = Broadband Inter-Carrier Interface DXIDXI = Data Exchange Interface = Data Exchange Interface

ATM LayersATM Layers

AdaptationAdaptation: mapping apps (eg: voice, data) to ATM cells: mapping apps (eg: voice, data) to ATM cells Physical layer:Physical layer: SONET etc SONET etc ATM Layer:ATM Layer: Transmission/Switching/Reception, Transmission/Switching/Reception,

Congestion Control, Cell header processing, Sequential Congestion Control, Cell header processing, Sequential delivery etc.delivery etc.

AAL Sublayers and AAL5AAL Sublayers and AAL5 : :

AAL SublayersAAL Sublayers Convergence Sublayer (CS)Convergence Sublayer (CS)

Determines Class of Service (CoS) for incoming trafficDetermines Class of Service (CoS) for incoming traffic Provides a specific AAL service at an AAL network service Provides a specific AAL service at an AAL network service

access point (NSAP)access point (NSAP) Segmentation and Reassembly Sublayer (SAR)Segmentation and Reassembly Sublayer (SAR)

Segments higher-level user data into 48-byte cells at the Segments higher-level user data into 48-byte cells at the sending node and reassembles cells at receiving nodesending node and reassembles cells at receiving node

AAL TypesAAL Types

AAL1: CBR voiceAAL1: CBR voice AAL5: data… AAL5: data…

ATM Physical Layer ATM Physical Layer FunctionsFunctions

Transports ATM cells on a communications Transports ATM cells on a communications channel and defines mechanical specs (connectors, channel and defines mechanical specs (connectors, etc.)etc.)

2 Sub-layers2 Sub-layers Transmission Convergence Sub-layerTransmission Convergence Sub-layer

Maps cells into the physical layer frame format (e.g. Maps cells into the physical layer frame format (e.g. DS1, STS3) on transmit and delineates ATM cells in the DS1, STS3) on transmit and delineates ATM cells in the received bit streamreceived bit stream

Generates HEC on transmitGenerates HEC on transmit Generates idle cells for cell rate decoupling, or speed Generates idle cells for cell rate decoupling, or speed

matchingmatching Physical Medium Sub-layerPhysical Medium Sub-layer

Medium dependent functions like bit transfer, bit Medium dependent functions like bit transfer, bit alignment, OEOalignment, OEO

Physical LayersPhysical Layers Multimode Fiber: 100 Mbps using 4b/5b,Multimode Fiber: 100 Mbps using 4b/5b, 155 Mbps SONET STS-3c, 155 Mbps 8b/10b155 Mbps SONET STS-3c, 155 Mbps 8b/10b Single-mode Fiber: 155 Mbps STS-3c, 622 MbpsSingle-mode Fiber: 155 Mbps STS-3c, 622 Mbps Plastic Optical Fiber: 155 MbpsPlastic Optical Fiber: 155 Mbps Shielded Twisted Pair (STP): 155 Mbps 8b/10bShielded Twisted Pair (STP): 155 Mbps 8b/10b Coax: 45 Mbps, DS3, 155 MbpsCoax: 45 Mbps, DS3, 155 Mbps Unshielded Twisted Pair (UTP)Unshielded Twisted Pair (UTP) UTP-3 (phone wire) at 25.6, 51.84, 155 MbpsUTP-3 (phone wire) at 25.6, 51.84, 155 Mbps UTP-5 (Data grade UTP) at 155 MbpsUTP-5 (Data grade UTP) at 155 Mbps DS1, DS3, STS-3c, STM-1, E1, E3, J2, n × T1DS1, DS3, STS-3c, STM-1, E1, E3, J2, n × T1

Take-home message:Take-home message: Serious attempt to inter-operate Serious attempt to inter-operate with several L1, L2 and L3 technologieswith several L1, L2 and L3 technologies

ATM Concepts: Virtual Paths & ATM Concepts: Virtual Paths & Virtual ChannelsVirtual Channels

VCs: way to ‘dial’ up and get bandwidthVCs: way to ‘dial’ up and get bandwidth

Call Establishment Using VPsCall Establishment Using VPs

Virtual circuits: Label Virtual circuits: Label Concept & Rationale for Concept & Rationale for

SignalingSignaling Two ways to use “packets”Two ways to use “packets”

carry entire destination address in headercarry entire destination address in header carry only an identifier, a.k.a “label”carry only an identifier, a.k.a “label”

Labels have “Labels have “locallocal” significance, addresses have ” significance, addresses have ““globalglobal” significance” significance

Signaling Signaling protocol: fundamentally protocol: fundamentally maps “global maps “global addresses” or pathsaddresses” or paths (sequence of addresses) (sequence of addresses) to local to local labelslabels Data

Data

DataVCI

Addr.

Sample

ATM cell

Datagram

VPI/VCI Assignment and VPI/VCI Assignment and UseUse

All packets must follow the All packets must follow the same path (why?)same path (why?)

Switches store per-VCI Switches store per-VCI state: eg: QoS infostate: eg: QoS info

Signaling => Signaling => separation of separation of data and controldata and control

Small Ids can be Small Ids can be looked up looked up (exact match) quickly in (exact match) quickly in hardwarehardware harder to do this with IP harder to do this with IP

addresses (longest-addresses (longest-prefix match)prefix match)

Setup must precede data Setup must precede data transfertransfer delays short messagesdelays short messages

SwitchedSwitched vs. vs. PermanentPermanent virtual circuitsvirtual circuits

ATM Cell StructureATM Cell Structure

ATM Cell Structure: ATM Cell Structure: Different ViewDifferent View

ATM Concepts: Fixed-size ATM Concepts: Fixed-size packetspackets

ProsPros Simpler buffer hardwareSimpler buffer hardware

packet arrival and departure requires us to manage packet arrival and departure requires us to manage fixed buffer sizesfixed buffer sizes

Simpler line schedulingSimpler line scheduling each cell takes a constant chunk of bandwidth to each cell takes a constant chunk of bandwidth to

transmittransmit Easier to build large parallel packet switchesEasier to build large parallel packet switches

ConsCons overhead for sending small amounts of dataoverhead for sending small amounts of data segmentation and reassembly costsegmentation and reassembly cost last unfilled cell after segmentation wastes last unfilled cell after segmentation wastes

bandwidthbandwidth

ATM Concepts: Small ATM Concepts: Small packet sizepacket size

At 8KHz, each byte is 125 microsecondsAt 8KHz, each byte is 125 microseconds The smaller the cell, the less an endpoint The smaller the cell, the less an endpoint

has to wait to fill ithas to wait to fill it Low packetization delayLow packetization delay

The smaller the packet, the larger the The smaller the packet, the larger the header overheadheader overhead

Standards body balanced the two to Standards body balanced the two to prescribe 48 bytes + 5 byte header = 53 prescribe 48 bytes + 5 byte header = 53 bytesbytes => maximal efficiency of 90.57%=> maximal efficiency of 90.57%

QoS Big Picture: QoS Big Picture: Control/Data PlanesControl/Data Planes

Internetw ork or W ANW orkstationRouter

Router

RouterW orkstation

Control Plane: Signaling + Admission Control orSLA (Contracting) + Provisioning/Traffic Engineering

Data Plane: Traffic conditioning (shaping, policing, markingetc) + Traffic Classification + Scheduling, Buffer management

ATM Concepts: Service ATM Concepts: Service CategoriesCategories

ABR (Available bit rate):ABR (Available bit rate): Source follows network feedback.Source follows network feedback. Max throughput with minimum loss.Max throughput with minimum loss.

UBR (Unspecified bit rate):UBR (Unspecified bit rate): User sends whenever it wants. No feedback. No User sends whenever it wants. No feedback. No

guarantee. Cells may be dropped during congestion.guarantee. Cells may be dropped during congestion. CBR (Constant bit rateCBR (Constant bit rate): User declares required rate.): User declares required rate.

Throughput, delay and delay variation guaranteed.Throughput, delay and delay variation guaranteed. VBR (Variable bit rate):VBR (Variable bit rate): Declare avg and max rate. Declare avg and max rate.

rt-VBR (Real-time):rt-VBR (Real-time): Conferencing. Conferencing. Max delay guaranteed.Max delay guaranteed.

nrt-VBR (non-real time):nrt-VBR (non-real time): Stored video. Stored video.

CBR and VBRCBR and VBR

Classes of ServiceClasses of Service The Convergence Sublayer (CS) interprets the type The Convergence Sublayer (CS) interprets the type

and format of incoming information based on 1 of 4 and format of incoming information based on 1 of 4 classes of service assigned by the applicationclasses of service assigned by the application

Class A:Class A: Constant bit rate ( Constant bit rate (CBRCBR), Connection oriented, strict ), Connection oriented, strict timing relationship between source and destination, i.e voicetiming relationship between source and destination, i.e voice

Class B:Class B: Variable bit rate ( Variable bit rate (VBRVBR), Connection oriented, strict ), Connection oriented, strict timing, e.g. packet-mode video for video conferencingtiming, e.g. packet-mode video for video conferencing

Class C:Class C: Connection oriented VBR, not strict timing, e.g. LAN Connection oriented VBR, not strict timing, e.g. LAN data transfer applications such as Frame Relaydata transfer applications such as Frame Relay Class D:Class D: Connectionless VBR, not strict timing, e.g. LAN data Connectionless VBR, not strict timing, e.g. LAN data transfer applications such as IPtransfer applications such as IP

ABR vs UBRABR vs UBR ABRABR

Queue in the sourceQueue in the source Pushes congestion to edgesPushes congestion to edges Good if end-to-end ATMGood if end-to-end ATM FairFair Good for the providerGood for the provider

UBRUBR Queue in the networkQueue in the network No backpressureNo backpressure Same end-to-end or backboneSame end-to-end or backbone Generally unfairGenerally unfair Simple for userSimple for user

ATM Signaling and QoS Routing ATM Signaling and QoS Routing (PNNI)(PNNI)

Source Destination

SETUP

SETUP

CONNECT

CONNECT

CONNECT ACK

CONNECT ACK

CALL PROCEEDING

CALL PROCEEDING

Network

UNI UNI

RELEASE

RELEASERELEASE COMPLETE

RELEASE COMPLETE

Figure 9.23 connection setup

Protocol Stacks for ATM Protocol Stacks for ATM SignalingSignaling

Sample Q.931 Message Sample Q.931 Message TypesTypes

Sample Information Sample Information ElementsElements

ATM Addresses: Basis for ATM Addresses: Basis for SignalingSignaling

Three NSAP-like (Network Service Access Point) address formats: Three NSAP-like (Network Service Access Point) address formats: DCC ATM Format, DCC ATM Format, ICD ATM Format, ICD ATM Format, E.164 ATM FormatE.164 ATM Format

ATM Address FormatsATM Address Formats

Authority and Format Identifier (AFI) & IDI:Authority and Format Identifier (AFI) & IDI: 39 = ISO DCC, 47 = British Stds Institute ICD, 45 = ITU ISDN 39 = ISO DCC, 47 = British Stds Institute ICD, 45 = ITU ISDN ISDN uses E.164 numbers (up to 15 BCD digits)ISDN uses E.164 numbers (up to 15 BCD digits) ATM forum extended E.164 addresses to NSAP format. ATM forum extended E.164 addresses to NSAP format. E.164 number is filled with leading zeros to make 15 digits. A FE.164 number is filled with leading zeros to make 15 digits. A F1616 is padded to is padded to

make 8 bytes.make 8 bytes. End System Identifier (ESI): 48-bit IEEE MAC address.End System Identifier (ESI): 48-bit IEEE MAC address. Selector is for use inside the host and is not used for routing.Selector is for use inside the host and is not used for routing. All ATM addresses are 20 bytes long.All ATM addresses are 20 bytes long.

NSAP vs SNPA Addressing: A NSAP vs SNPA Addressing: A ClarificationClarification

NSAPNSAP = Network Service Access = Network Service Access Point. Identifies network layer Point. Identifies network layer service entryservice entry

SNPASNPA = Sub-network point of = Sub-network point of attachment. Identifies the attachment. Identifies the interface to sub-networkinterface to sub-network SNPA address (or part of it) is used SNPA address (or part of it) is used

to carry the packet across the to carry the packet across the network.network.

CLNP uses CLNP uses NSAPNSAP to deliver the to deliver the packet to the right entity in the packet to the right entity in the host.host.

ATM uses ATM uses NSAP-like encodingNSAP-like encoding but ATM addresses identify but ATM addresses identify SNPA and not NSAP.SNPA and not NSAP.

ATM Connection TypesATM Connection Types Permanent and SwitchedPermanent and Switched Point to pointPoint to point Symmetric or asymmetric bandwidth (Uni- Symmetric or asymmetric bandwidth (Uni-

or bi-directional)or bi-directional) Point-to-multipoint: Data flow in one Point-to-multipoint: Data flow in one

direction only.direction only. Data replicated by network.Data replicated by network.

Source Switch

Transit Switch

Destination Switch

Source A Destination B

SETUPSETUP

SETUPSETUP

CONNECTCONNECT

CONNECTCONNECT

CONNECT ACK CONNECT ACKCONNECT ACK

CONNECT ACK

CALL PROCEEDING CALL PROCEEDINGCALL PROCEEDING

CALL PROCEEDING

RELEASE

RELEASE

RELEASERELEASE

RELEASE COMPLETERELEASE COMPLETE

RELEASE COMPLETERELEASE COMPLETE

Figure 9.25

ATM Routing: PNNIATM Routing: PNNI

Private Network-to-network InterfacePrivate Network-to-network Interface Private Network Node InterfacePrivate Network Node Interface

Private Network to Node Private Network to Node Interface (PNNI)Interface (PNNI)

Link State Routing Protocol for ATM Link State Routing Protocol for ATM NetworksNetworks

““A hierarchy mechanism ensures that A hierarchy mechanism ensures that this protocol scales well for large world-this protocol scales well for large world-wide ATM networks. A key feature of the wide ATM networks. A key feature of the PNNI hierarchy mechanism is its ability PNNI hierarchy mechanism is its ability to automatically configure itself in to automatically configure itself in networks in which the address structure networks in which the address structure reflects the topology…reflects the topology…””

PNNI FeaturesPNNI Features Scales to very large networks.Scales to very large networks. Supports hierarchical routing.Supports hierarchical routing. Supports QoS.Supports QoS. Supports multiple routing metrics and attributes.Supports multiple routing metrics and attributes. Uses source routed connection setup.Uses source routed connection setup. Operates in the presence of partitioned areas.Operates in the presence of partitioned areas. Provides dynamic routing, responsive to changes in Provides dynamic routing, responsive to changes in

resource availability.resource availability. Separates the routing protocol used within a peer Separates the routing protocol used within a peer

group from that used among peer groups.group from that used among peer groups. Interoperates with external routing domains, not Interoperates with external routing domains, not

necessarily using PNNI.necessarily using PNNI. Supports both physical links and tunneling over VPCs.Supports both physical links and tunneling over VPCs.

PNNI Terminology PNNI Terminology (partial)(partial) Peer group:Peer group: A group of nodes at the same hierarchy A group of nodes at the same hierarchy

Border node:Border node: one link crosses the boundary one link crosses the boundary Logical group node:Logical group node: Representation of a group as a Representation of a group as a

single pointsingle point Child node:Child node: Any node at the next lower hierarchy level Any node at the next lower hierarchy level Parent node:Parent node: LGN at the next higher hierarchy level LGN at the next higher hierarchy level Logical links:Logical links: links between logical nodes links between logical nodes Peer group leader (PGL):Peer group leader (PGL): Represents a group at the Represents a group at the

next higher level.next higher level. Node with the highest "leadership priority" and highest ATM address is Node with the highest "leadership priority" and highest ATM address is

elected as a leader.elected as a leader. PGL acts as a logical group node.PGL acts as a logical group node. Uses same ATM address with a different selector value.Uses same ATM address with a different selector value.

Peer group ID:Peer group ID: Address prefixes up to 13 bytes Address prefixes up to 13 bytes

Peer Group Leader

Figure 9.26

PNNI HierarchicalPNNI Hierarchical

Call Admission ControlCall Admission Control

Source RoutingSource Routing

Source specifies route as a list of all intermediate Source specifies route as a list of all intermediate systems in the route (original idea in token ring)systems in the route (original idea in token ring)

Designated Transit List (DTL):Designated Transit List (DTL): Source route across each level of hierarchySource route across each level of hierarchy

Entry switch of each peer group specifies complete route Entry switch of each peer group specifies complete route through that groupthrough that group

Set of DTLs and manipulations implemented as a stackSet of DTLs and manipulations implemented as a stack

Traffic Management: Traffic Management: ATMATM

Traffic Management Traffic Management FunctionsFunctions

Connection Admission Control (CAC):Connection Admission Control (CAC): Can requested bandwidth and Can requested bandwidth and quality of service be supported?quality of service be supported?

Traffic Shaping:Traffic Shaping: Limit burst length. Space-out cells. Limit burst length. Space-out cells.

Usage Parameter Control (UPC):Usage Parameter Control (UPC): Monitor and control traffic at the Monitor and control traffic at the network entrance.network entrance.

Network Resource ManagementNetwork Resource Management: Scheduling, Queueing, virtual path : Scheduling, Queueing, virtual path resource reservationresource reservation

Selective cell discard:Selective cell discard: Cell Loss Priority (CLP) = 1 cells may be droppedCell Loss Priority (CLP) = 1 cells may be dropped Cells of non-compliant connections may be droppedCells of non-compliant connections may be dropped Frame DiscardingFrame Discarding

Feedback Control:Feedback Control: ABR schemes ABR schemes

Traffic Contract Traffic Contract ParametersParameters

Peak Cell Rate (Peak Cell Rate (PCRPCR): 1/T): 1/T Sustained Cell Rate (Sustained Cell Rate (SCRSCR): Average over a long period): Average over a long period

Burst Tolerance (Burst Tolerance (BTBT) ts : GCRA limit parameter wrt SCR ) ts : GCRA limit parameter wrt SCR GCRA(1/Ts, ts)GCRA(1/Ts, ts)

Maximum Burst Size: Maximum Burst Size: MBSMBS = = 1+BT/(1/SCR-1/PCR) 1+BT/(1/SCR-1/PCR) BT BT [(MBS-1)(1/SCR-1/PCR), MBS(1/SCR- 1/PCR)][(MBS-1)(1/SCR-1/PCR), MBS(1/SCR- 1/PCR)]

Cell Transfer Delay (Cell Transfer Delay (CTDCTD): First bit in to last bit out): First bit in to last bit out Cell Delay Variation (Cell Delay Variation (CDVCDV): ~ Max CTD - Min CTD): ~ Max CTD - Min CTD

Peak-to-peak CDVPeak-to-peak CDV Cell Delay Variation Tolerance (Cell Delay Variation Tolerance (CDVTCDVT) t = GCRA limit ) t = GCRA limit

parameter wrt PCR Þ GCRA(T, t)parameter wrt PCR Þ GCRA(T, t)

Cell Loss Ratio (Cell Loss Ratio (CLRCLR): Cells lost /Totals cells sent): Cells lost /Totals cells sent Minimum cell rate (Minimum cell rate (MCRMCR))

Peak-to-Peak CDVPeak-to-Peak CDV

Service CategoriesService Categories

IP OVER ATMIP OVER ATM

ATM: Lan EmulationATM: Lan Emulation

ATM Lan Emulation ATM Lan Emulation (LANE)(LANE)

One ATM LAN can be One ATM LAN can be n n virtual LANsvirtual LANs Logical subnets interconnected via routersLogical subnets interconnected via routers Need drivers in hosts to support each LANNeed drivers in hosts to support each LAN Only IEEE 802.3 and IEEE 802.5 frame formats Only IEEE 802.3 and IEEE 802.5 frame formats

supported. (FDDI can be easily done.)supported. (FDDI can be easily done.) Doesn't allow passive monitoringDoesn't allow passive monitoring No token management (SMT), collisions, beacon No token management (SMT), collisions, beacon

frames.frames. Allows larger frames.Allows larger frames.

LAN Emulation (Contd)LAN Emulation (Contd)

LAN Emulation driver replaces Ethernet driver and LAN Emulation driver replaces Ethernet driver and passes the networking layer packets to ATM driverpasses the networking layer packets to ATM driver..

Each ATM host is assigned an Ethernet addressEach ATM host is assigned an Ethernet address..LAN Emulation Server translates Ethernet LAN Emulation Server translates Ethernet

addresses to ATM addressesaddresses to ATM addressesHosts set up a VC and exchange packetsHosts set up a VC and exchange packetsAll software that runs of Ethernet can run on LANEAll software that runs of Ethernet can run on LANE

LAN Emulation (Contd)LAN Emulation (Contd)

Protocol Layering w/ LAN Protocol Layering w/ LAN EmulationEmulation

TerminologyTerminology NDIS = Network Driver Interface NDIS = Network Driver Interface

SpecificationSpecification ODI = Open Datalink InterfaceODI = Open Datalink Interface IPX = NetWare Internetworking ProtocolIPX = NetWare Internetworking Protocol LAN Emulation SoftwareLAN Emulation Software::

LAN Emulation Clients in each hostLAN Emulation Clients in each host LAN Emulation ServersLAN Emulation Servers LAN Emulation Configuration server (LECS)LAN Emulation Configuration server (LECS) LAN Emulation Server (LES)LAN Emulation Server (LES) Broadcast and unknown server (BUS)Broadcast and unknown server (BUS)

LAN Emulation ProcessLAN Emulation Process

InitializationInitialization:: Client gets address of LAN EmulationClient gets address of LAN Emulation Configuration Server (LECS) from its Configuration Server (LECS) from its

switch, uses well-known LECS address, switch, uses well-known LECS address, or well known LECS PVCor well known LECS PVC

Client gets Server's address from LECSClient gets Server's address from LECS Registration:Registration:

Client sends a list of its MAC addresses Client sends a list of its MAC addresses to Server.to Server.

Declares whether it wants ARP requests.Declares whether it wants ARP requests.

LANE ProcessLANE Process Address Resolution:Address Resolution:

Client sends ARP request to Server.Client sends ARP request to Server. Unresolved requests sent to clients, bridges.Unresolved requests sent to clients, bridges. Server, Clients, Bridges answer ARPServer, Clients, Bridges answer ARP Client setups a direct connectionClient setups a direct connection

Broadcast/Unknown Server (BUS):Broadcast/Unknown Server (BUS): Forwards multicast traffic to all membersForwards multicast traffic to all members Clients can also send unicast frames for Clients can also send unicast frames for

unknown addressesunknown addresses

ATM Virtual LANsATM Virtual LANs

ATM interfaces with ATM interfaces with InternetworkingInternetworking