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<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong><br />

Chapter 2<br />

ATM<br />

Dr.-Ing. Falko Dressler<br />

Chair for <strong>Computer</strong> Networks & <strong>Internet</strong><br />

Wilhelm-Schickard-Institute for <strong>Computer</strong> Science<br />

University of Tübingen<br />

http://net.informatik.uni-tuebingen.de/<br />

dressler@informatik.uni-tuebingen.de<br />

<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong>, SS 2004 2.1


Basics of ATM<br />

Introduction<br />

Chapter 2<br />

ATM<br />

Reference Model<br />

Higher Layers<br />

Signaling, Routing<br />

IP over ATM<br />

LAN over ATM<br />

<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong>, SS 2004 2.2


B-ISDN <strong>and</strong> ATM<br />

The goal of broadb<strong>and</strong> ISDN (1990)<br />

Worldwide consistently build high-performance network<br />

Transmission of data, audio, video<br />

St<strong>and</strong>ardization via ITU (CCITT)<br />

ATM (Asynchronous Transfer Mode) was selected as the base<br />

technology for B-ISDN<br />

Therefore, ATM is part of the ITU specification of B-ISDN<br />

<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong>, SS 2004 2.3


Introduction<br />

ATM: Asynchronous Transfer Mode<br />

Based on st<strong>and</strong>ardized protocols<br />

Integrated technology for multiple services<br />

Data<br />

Speech / Audio<br />

Video<br />

Usable in LAN <strong>and</strong> WAN areas<br />

Highly scalable<br />

Support for different connection qualities -> Real-time!<br />

Employment of asynchronous time multiplex technologies for flexibility<br />

in support of various transmission b<strong>and</strong>widths<br />

<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong>, SS 2004 2.4


Properties<br />

Data packets of fixed size, named cells<br />

ATM cells have a length of 53 byte (5 byte header, 48 byte payload)<br />

This allows a high speed processing including massive parallel hardware<br />

operations<br />

Connection oriented<br />

point-to-point<br />

point-to-multipoint<br />

Connections may have a fixed (reserved) b<strong>and</strong>width <strong>and</strong> guaranteed<br />

quality of service characteristics<br />

Centralized coordination of permissions to send (in contrast to token<br />

techniques or CSMA/CD)<br />

No shared medium<br />

Dedicated b<strong>and</strong>width<br />

<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong>, SS 2004 2.5


St<strong>and</strong>ardization<br />

ITU-T: International Telecommunications Union – Telecommunications<br />

St<strong>and</strong>ards Section (formerly CCITT)<br />

http://www.itu.ch/<br />

ETSI: European Telecommunications St<strong>and</strong>ards Institute<br />

http://www.etsi.fr/<br />

ANSI: American National St<strong>and</strong>ards Institute<br />

http://web.ansi.org/<br />

ATM-Forum<br />

Development of industry st<strong>and</strong>ards allowing a fest development of new<br />

products<br />

http://www.atmforum.com/<br />

<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong>, SS 2004 2.6


ATM Layer Model<br />

User plane: information flow between the layers<br />

Control plane: connection setup, maintenance <strong>and</strong> termination<br />

Management plane: meta-signaling <strong>and</strong> OAM information flow<br />

<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong>, SS 2004 2.7


Physical Layer<br />

Physical medium sends <strong>and</strong> receives a bit stream<br />

Bit timing<br />

Transmission convergence<br />

The physical layer adopts the ATM cells received from the ATM layer<br />

to the bit stream required by the physical layer (cell coding)<br />

Direct cell transmission<br />

Cell adaptation to existing transmission frames<br />

PLCP based cell adaptation<br />

HEC generation<br />

Information flow to the management <strong>and</strong> to the supervision at the<br />

physical layer (OAM)<br />

<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong>, SS 2004 2.8


Physical Layer II<br />

Transmission speeds<br />

PDH (Plesiochronous Digital Hierarchy)<br />

Europe: 2,048 Mbit/s, 8,448 Mbit/s, 34,368 Mbit/s, 139,264 Mbit/s<br />

USA: 1,544 Mbit/s, 6,312 Mbit/s, 44,736 Mbit/s, 254,176 Mbit/s<br />

SDH (Synchronous Digital Hierarchy)<br />

OC-3: 155,520 Mbit/s<br />

OC-12: 622,080 Mbit/s<br />

Today: OC-48, OC-192, …<br />

<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong>, SS 2004 2.9


ATM Layer<br />

Transport of ATM cells between the communication end points<br />

Tasks of the user <strong>and</strong> control plane<br />

Connection setup, multiplexing/de-multiplexing <strong>and</strong> maintaining ATM<br />

connection<br />

Generation of ATM cell headers (but HEC)<br />

Negotiation of QoS parameters<br />

Traffic <strong>and</strong> overload control<br />

OAM cells (management plane)<br />

Meta-signaling<br />

<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong>, SS 2004 2.10


ATM Cell Format<br />

53 Byte<br />

5 Byte Header<br />

48 Byte Payload<br />

<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong>, SS 2004 2.11


ATM Cell Types<br />

UNI/NNI cells: data communication<br />

Transmission of user data<br />

Transmission of signaling data (connection setup, maintenance, tear down)<br />

VP/VC OAM cells (F4 <strong>and</strong> F5)<br />

Idle cells: decoupling of the cell rate at the sender <strong>and</strong> the available b<strong>and</strong>width<br />

of the transmission medium<br />

Empty cells: contain VPI/VCI but no payload<br />

OAM cells: contain control <strong>and</strong> service information<br />

Reserved VCI/VPI values<br />

Function VPI/VCI<br />

Meta signaling VCI=1, VPI=0<br />

ILMI VCI=16, VPI=0<br />

Point-to-point signaling VCI=5<br />

PNNI VCI=18, VPI=0<br />

….<br />

<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong>, SS 2004 2.12


Virtual Channels<br />

ATM Connections<br />

2 Hierarchies: paths <strong>and</strong> channels<br />

Virtual Path<br />

Transmission Path<br />

<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong>, SS 2004 2.13


Properties of ATM Connections<br />

Start <strong>and</strong> end at higher layer functions<br />

Have associated service parameters (e.g. cell loss ratio, latency)<br />

Negotiation of transmission parameters before a connection is set up<br />

(provision of QoS)<br />

Preservation of the transmission order<br />

Unidirectional or bidirectional<br />

Symmetric or asymmetric b<strong>and</strong>width<br />

Permanent<br />

PVC: Permanent Virtual Channel<br />

Dynamic<br />

SVC: Switched Virtual Channel<br />

Signaling: connection setup <strong>and</strong> tear down<br />

(ATM Forum: UNI 3.1, UNI 4.0)<br />

Routing Protocols (ATM-Forum: P-NNI)<br />

Addressing<br />

<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong>, SS 2004 2.14


Traffic <strong>and</strong> Overload Control<br />

Traffic Management 4.0 (ATM Forum)<br />

Connection admission control<br />

Verification if connection setup would be possible<br />

User/network parameter control (UPC/NPC)<br />

Supervision of transmission b<strong>and</strong>width by setting a cell loss priority <strong>and</strong><br />

selectively discarding of cells<br />

Traffic shaping<br />

adjustment / smoothing of the transmission rate<br />

Early packet discard<br />

discarding of complete AAL PDUs if single cells are lost<br />

<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong>, SS 2004 2.15


Call Admission Control<br />

Exchange of information during the connection setup<br />

Source traffic descriptor<br />

Peak cell rate (PCR): upper bound for the maximum cell transmission rate [c/s]<br />

Sustainable cell rate (SCR): upper bound for the average cell transmission rate<br />

[c/s]<br />

Maximum burst size (MBS): size of a buffer used for short bursts [c]<br />

Minimum cell rate (MC): lower bound for the cell transmission rate [c/s]<br />

Cell delay variation tolerance (CDVT): lower bound for the minimum<br />

distance between two cells<br />

(generated by multiplexing, OAM cells, …)<br />

QoS of the connection (QoS parameters)<br />

Successful completion of the CAC<br />

Traffic agreement is negotiated between the network <strong>and</strong> the end systems<br />

<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong>, SS 2004 2.16


UPC/NPC<br />

Usage Parameter Control / Network Parameter Control<br />

Verification of<br />

Correctness of the VP/VC identifiers in the cell header<br />

Conformance of the cell stream (compliance with the negotiated traffic<br />

profile)<br />

Actions<br />

Cell passing<br />

Cell tagging (warning)<br />

Cell discarding (in overload situations)<br />

Generic cell rate algorithm (GCRA)<br />

For every cell, a theoretical arrival time (TAT) is calculated based on the<br />

assumption that the distance between all cells is equal<br />

If the actual arrival time corresponds with the TAT (taking a tolerance into<br />

account), the cell is conform<br />

<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong>, SS 2004 2.17


UPC/NPC II<br />

UPC typically at the ingress of an ATM switch<br />

One or two leaky buckets depending on the service category<br />

<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong>, SS 2004 2.18


Traffic Shaping<br />

Implementation using a leaky bucket<br />

Reduction of the burst size <strong>and</strong> removal of the cell delay variation (by<br />

increasing the delay)<br />

Important note: the order of the cells is not changed<br />

<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong>, SS 2004 2.19


Early Packet Discard<br />

EPD buffer threshold to prevent overload situations<br />

If threshold is exceeded, complete AAL5 PDUs are dropped<br />

→ performance enhancement<br />

<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong>, SS 2004 2.20


Quality of Service<br />

Parameter are negotiated at connection setup (ITU I.356/UNI4.0)<br />

Cell error ratio<br />

Severely errored blocks<br />

Cell loss ratio*<br />

Cell misinsertion ratio<br />

Cell transfer delay*<br />

Mean cell transfer delay<br />

Cell delay variation*<br />

*: currently unused<br />

Different classes (ATM-Forum)<br />

Constant bit-rate (CBR)<br />

Delay sensitive CBR cell stream<br />

Variable bit rate - real time (VBR-rt)<br />

Delay sensitive VBR cell stream<br />

Variable bit rate - non real time (VBR-nrt)<br />

Delay insensitive VBR cell stream<br />

Unspecified bit rate (UBR)<br />

Best effort<br />

Available bit rate (ABR)<br />

Dynamic b<strong>and</strong>width allocation if available<br />

<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong>, SS 2004 2.21


Quality of Service II<br />

Attribute CBR VBR-rt VBR-nrt UBR ABR<br />

Traffic parameters<br />

PCR <strong>and</strong> CDVT(pcr)<br />

SCR, MBS, CDVT(scr)<br />

MCR<br />

QoS parameters<br />

Peak-peak CDVT<br />

maxCTD<br />

CLR<br />

Specified<br />

n/a<br />

n/a<br />

Specified<br />

Specified<br />

Specified<br />

Specified<br />

Specified<br />

n/a<br />

Specified<br />

Specified<br />

Specified<br />

Specified<br />

Specified<br />

<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong>, SS 2004 2.22<br />

n/a<br />

Unspecified<br />

Unspecified<br />

Specified<br />

Specified<br />

n/a<br />

n/a<br />

Unspecified<br />

Unspecified<br />

Unspecified<br />

Specified<br />

n/a<br />

Specified<br />

Unspecified<br />

Unspecified<br />

Flow control<br />

Closed loop Unspecified Unspecified Unspecified Unspecified Specified


ATM Adaptation Layer<br />

AAL (ATM Adaptation Layer): mapping data structures between higher<br />

layers <strong>and</strong> ATM cells<br />

Criteria:<br />

Time constraints<br />

Bit rate (constant, variable)<br />

Connection type (connection oriented / connection less)<br />

Convergence Sublayer (CS)<br />

Building CS-PDUs out of an application generated byte stream<br />

Segmentation <strong>and</strong> Reassembly Sublayer (SAR)<br />

Convert CS-PDUs into 48 byte fragments which fit in the payload of ATM cells<br />

<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong>, SS 2004 2.23


ATM Adaptation Layer II<br />

<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong>, SS 2004 2.24


ATM Adaptation Layer III<br />

AAL0: “native” ATM<br />

AAL1: constant bit rate (circuit emulation)<br />

AAL2: transmission of data streams with variable bit rates <strong>and</strong> well defined<br />

time constraints between sender <strong>and</strong> receiver<br />

AAL3/4: Variable bit rate without any time constraints<br />

AAL5: simplified AAL3/4 (no multiplexing of cells)<br />

SAAL: Signaling<br />

<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong>, SS 2004 2.25


Convergence Sublayer<br />

Common part: to add / to remove header <strong>and</strong> trailer<br />

Unreliable transmission of data packets of variable length<br />

Connection setup between two CPCS end points<br />

Preservation of the order within a single CPCS connection<br />

Error detection <strong>and</strong> h<strong>and</strong>ling<br />

H<strong>and</strong>ling of overload information<br />

H<strong>and</strong>ling of cell loss priorities<br />

Dropping of incomplete CPCS PDUs<br />

Service specific:<br />

Q.SAAL (SSCS: specification for signaling channels)<br />

<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong>, SS 2004 2.26


Segmentation <strong>and</strong> Reassembly Sublyaer<br />

Identification of the next SAP PDU to transmit<br />

PTI informs about start <strong>and</strong> end of a SAR PDU<br />

H<strong>and</strong>ling of overload<br />

H<strong>and</strong>ling of cell loss priorities<br />

Check for ordering of SAR PDUs<br />

<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong>, SS 2004 2.27


SAAL<br />

SAAL: Adaptation layer for signaling<br />

meta signaling<br />

signaling AAL<br />

ITU Q.2100<br />

Offers a reliable service for the higher layer signaling (Q.2931)<br />

Q.2931 has no error correction mechanisms<br />

SSCS sublayer: realizes SSCOP protocol (Service Specific<br />

Connection Oriented Protocol)<br />

Sequence continuity<br />

Error correction, retransmission<br />

Flow control<br />

Keep alive<br />

Connection control<br />

Exchange of status information between sender <strong>and</strong> receiver<br />

<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong>, SS 2004 2.28


Operation, Administration <strong>and</strong> Maintenance<br />

Information flow for management <strong>and</strong> control<br />

Cells can be identified by the PT field<br />

Error control <strong>and</strong> localization<br />

Performance control<br />

5 hierarchies: F1-F5<br />

Physical layer: F1-F3<br />

SDH encoding: F1, F2: section overhead, F3: path overhead<br />

PDH encoding: using PDH internal structures<br />

Indication of unavailability state, transport of defect information to the<br />

end system, MUX problems<br />

ATM layer: F4, F5<br />

Fault management<br />

Transmission of defect information in both directions<br />

– AIS - Alarm Indication Signal: sent upstream to indicate downstream failures<br />

– RDI - Remote Indication Signal: sent downstream to indicate upstream failures<br />

Continuity check<br />

Loopback cells: monitoring, fault localization<br />

Performance management<br />

<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong>, SS 2004 2.29


ATM Components<br />

ATM Hosts<br />

ATM Switches<br />

ATM Edge Devices<br />

Interconnection of ATM networks <strong>and</strong> non-ATM networks<br />

ATM Interfaces (public/private)<br />

UNI (User Network Interface): defines protocols for the communication between<br />

hosts <strong>and</strong> switches<br />

NNI (Network to Network Interface): defines the interface between two network<br />

components<br />

<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong>, SS 2004 2.30


Higher Layers<br />

Signaling, Routing<br />

UNI – User Network Interface<br />

PNNI - Private Network-to-Network Interface<br />

ILMI - Integrated Local Management Interface<br />

<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong>, SS 2004 2.31


User Network Interface – Connection Setup<br />

Host A: specification of b<strong>and</strong>width, QoS <strong>and</strong> destination address<br />

Within the network:<br />

Verification of the available resources<br />

Acceptance / rejection of the request<br />

Reservation of the required resources<br />

Maintenance of the routing tables<br />

Host B: acceptance / rejection of the connection request<br />

<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong>, SS 2004 2.32


User Network Interface – Connection Release<br />

Host A: connection release message<br />

Within the network:<br />

Release of resources belonging to the connection<br />

Acknowledgement of the connection release message<br />

Host B: acknowledgement of the connection release message<br />

<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong>, SS 2004 2.33


User Network Interface III<br />

ATM point-to-multipoint connections<br />

Extensions in UNI 4.0 Signaling<br />

Multicast (leaf initiated join)<br />

Frame discard<br />

Signaling of more QoS parameters (CLR, meanCTD, maxCTD, CDV, ....)<br />

<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong>, SS 2004 2.34


Private Network-to-Network Interface Protocol<br />

P-NNI: also known as Private Network Node Interface Protocol<br />

Setup of SVCs in networks with NSAP addressing in a multivendor<br />

environment<br />

Hierarchical routing structure, similar to OSPF<br />

Using topology <strong>and</strong> resource information to setup paths<br />

Phase 0: Inter-Switch Signaling Protocol (IISP)<br />

Signaling protocol for the communication between ATM switches<br />

(administratively configurable address prefixes)<br />

Phase 1:<br />

QoS support<br />

scalability <strong>and</strong> reachability<br />

Signaling is based on UNI3.1/4.0 with some extensions<br />

<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong>, SS 2004 2.35


P-NNI - QoS<br />

CAC (connection admission control)<br />

Admission control at each node along the path<br />

Topology state protocol<br />

GCAC (generic CAC)<br />

Determination of the shortest path over all nodes which comply with the<br />

ABR <strong>and</strong> CLR<br />

Additionally, the path is versified using the QoS requirements (CDV, …)<br />

Source node creates a “Designated Transit List“ containing the complete<br />

route<br />

Cranback: possibility for a rollback<br />

<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong>, SS 2004 2.36


P-NNI - Hierarchy<br />

Scalability: hierarchical routing protocol<br />

Summary of the reachability information at each hierarchy<br />

Identification using NSAP addresses<br />

Problems:<br />

internetworking with<br />

other networks<br />

Complexity in route<br />

aggregation<br />

<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong>, SS 2004 2.37


Integrated Local Management Interface<br />

Protocol for the bidirectional exchange of management information<br />

Monitoring of systems<br />

Management of systems<br />

Using SNMP (simple network management protocol) for the<br />

communication (without UDP/IP addressing)<br />

Fundamentals: data base (ATM-UNI-MIB) with well defined comm<strong>and</strong>s<br />

for accessing the data base: AAL encapsulated SNMP messages,<br />

community name ILMI<br />

<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong>, SS 2004 2.38


ILMI - Address Registration<br />

Bidirectional address registration<br />

Dynamic exchange of address information between end systems <strong>and</strong><br />

the network at the UNI<br />

The ATM host informs the switch about its ESI address<br />

The ATM switch provides the address prefix to the host<br />

Protocol for automatic address registration<br />

Benefits:<br />

There is no need to configure the prefix at each host<br />

There is no need for an additional address resolution protocol in the<br />

switches (all hosts register first)<br />

<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong>, SS 2004 2.39


Applications<br />

Multimedia<br />

Video over ATM<br />

Benefits:<br />

guaranteed QoS parameters<br />

Low latency<br />

Resource sharing between multiple applications<br />

Drawbacks:<br />

Complexity in the maintenance of ATM networks<br />

Examples:<br />

M-JPEG codecs: 15Mbit/s, TV quality<br />

MPEG2 codecs: 3-40Mbit/s, DVD up to studio quality<br />

Lossless SDI: 270Mbit/s, uncompressed studio signals<br />

IP/LAN over ATM<br />

Classical IP, MPOA<br />

LAN Emulation<br />

<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong>, SS 2004 2.40


Multiprotocol Encapsulation over AAL5 (RFC2684)<br />

RFC2684<br />

LLC/SNAP encapsulation<br />

LLC data packets are encapsulated into AAL5 CPCS PDUs<br />

Transmission of a complete data stream in a single VC<br />

A special header informs about the encapsulated protocol<br />

All protocols based on Ethernet, FDDI, … can be transported<br />

VC based multiplexing<br />

<strong>Communication</strong> end point in layer 3<br />

Avoidance of special LLC headers by using separate VCs for each<br />

protocol<br />

More efficient than LLC encapsulation<br />

<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong>, SS 2004 2.41


Classical IP<br />

Specification of a complete IP implementation for ATM<br />

Allows unicast communication only<br />

Very efficient<br />

Support for large MTU sizes<br />

Direct encapsulation of IP packets into AAL PDUs<br />

LIS: logical IP subnet<br />

ATMARP/InATMARP: protocol similar to ARP to resolve IP to ATM addresses<br />

InATMARP functions are provided by an ATMARP server<br />

There must be an ATMARP server in each LIS<br />

<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong>, SS 2004 2.42


Classical IP II<br />

Each ARP client must register its IP/ATM address information at the<br />

ATMARP server or request an IP address from the ATMARP server<br />

<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong>, SS 2004 2.43


LANE<br />

LAN Emulation: connecting LANs over ATM networks<br />

The properties of ATM are completely hidden<br />

Complete emulation of the LAN MAC layer<br />

Thus, no need to modify existing LAN software<br />

But, no special ATM features can be used, e.g. QoS<br />

Provisioning of a special broadcast mechanism, which is also used for<br />

multicast<br />

Translation of MAC to ATM addresses<br />

Transmission of LAN packets using AAL5 PDUs<br />

Modules:<br />

LANE client (LEC)<br />

LANE server (LES)<br />

LANE configuration server (LECS)<br />

Broadcast <strong>and</strong> unknown server (BUS)<br />

<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong>, SS 2004 2.44


LANE II<br />

LEC (LANE client)<br />

Control functions<br />

Data exchange using the ATM interface<br />

Interface to the application as a st<strong>and</strong>ard LAN MAC interface<br />

LES (LANE server)<br />

Control <strong>and</strong> maintenance of an E-LAN (emulated LAN)<br />

Registration of LECs<br />

Mapping of MAC to ATM addresses<br />

BUS (broadcast <strong>and</strong> unknown server)<br />

Delivery of broadcast, multicast <strong>and</strong> unknown packets received from any<br />

LANE client<br />

All packets with a broadcast or multicast address<br />

Packets which cannot be delivered directly, e.g. because the<br />

corresponding ATM address cannot be resolved<br />

Sequential processing of the single messages (AAL5 does not allow the<br />

change of the order of PDUs)<br />

<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong>, SS 2004 2.45


LANE III<br />

LECS (LANE configuration server)<br />

Management of the different emulated LANs <strong>and</strong> the associated LANE<br />

servers<br />

Configuration database allowing a LANE client to find the appropriate<br />

LANE server for a specific emulated LAN<br />

LECS address<br />

Statically configured in LES <strong>and</strong> LEC<br />

Well known address<br />

via ILMI<br />

<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong>, SS 2004 2.46


LANE IV<br />

<strong>Advanced</strong> <strong>Internet</strong> <strong>Technologies</strong>, SS 2004 2.47

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