Atm a view from the trenches
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ATM: A view from the trenches. Introduction. Laura Grill: l-grill@nwu.edu *my* experience with ATM cisco environment at Northwestern University. Agenda. Why ATM? Review of basic ATM theory and LANE A look at NU’s network topology. Why ATM?. 1996 ATM was the next big thing

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Introduction
Introduction

  • Laura Grill: l-grill@nwu.edu

  • *my* experience with ATM

  • cisco environment at Northwestern University


Agenda
Agenda

  • Why ATM?

  • Review of basic ATM theory and LANE

  • A look at NU’s network topology


Why atm
Why ATM?

  • 1996 ATM was the next big thing

    • connection oriented benefits of circuit switched using virtual circuits

    • efficient use of bandwidth as in packet switched

  • Decision was made at executive level for:

    • combine voice and data worlds

    • ATM to the desktop

  • 1997 built ATM backbone and bought OC-12 to Ameritech NAP

    • to handle voice data and video to and from the university


New technologies new strategy
New technologies:New strategy

  • The enabling technologies that make it feasible to integrate services w/o ATM

    • voice over IP

    • QOS for connectionless networks

    • gigabit ethernet

  • Today, ATM as a backbone and wan technology w/ no plans to grow it

  • Moving gigabit into the backbone (keeping existing ATM)

  • Frame versus cell: I'd rather have frames


Basic atm theory
Basic ATM theory

  • Connection oriented vs. connectionless

  • 53 byte cells

  • Uses virtual circuits, identified with VPI/VCI


Broadcast based legacy protocols
Broadcast based "legacy" protocols

  • IP, IPX, AppleTalk (use broadcast discovery)

  • Why is this a problem?

  • Catch 22 - can’t talk on the network until a circuit is established and can’t establish a circuit without an address

  • Can’t broadcast on the phone network (no mechanism for this)


Ways to solve the broadcast problem
Ways to solve the broadcast problem

  • RFC 1483 [native IP over ATM]

  • RFC 1577 [classical IP]

  • LANE (LAN Emulation)

  • MPOA


Lane system
LANE system

  • 3 servers: LECS, LES, BUS

  • 1 client: LEC


Servers
Servers

  • LECS - LAN Emulation Configuration Server

    • hold information about the LES for each emulated LAN and gives that info to the LEC when it comes on-line

  • LES - client register their MAC and ATM address with the LES

  • BUS- maintains a VC that connects all the clients together emulated a broadcast


Client
Client

  • LEC - LAN Emulation Client (can be a host or router or switch)


Procedure for a lec to become part of the emulated lan
Procedure for a LEC to become part of the emulated LAN

  • LEC comes up and creates VC to LECS (using well known address or ILMI or statically configured)

  • LECS tells it what to emulate and who the LES is and what it's ATM address is

  • The client then registers it's MAC and ATM address with the LES

  • LES assigns a BUS

  • At this point many VC’s have been built to mesh all the LEC’s together


Atm topology at nu
ATM Topology at NU

  • See diagrams

  • ATM as a backbone technology to connect buildings to the core

  • use ATM for our WAN - OC-3c to NAP and OC-3c to Chicago campus

  • Some FDDI still remains

  • Will add gigabit this year


The end
The end

  • Questions?