http://www.gmd.de

Did MPOA achieve its objective?

TERENA Networking Conference 2000

Lisbon, Portugal 22-25 May 2000

Ferdinand Hommes, Eva Pless, Lothar ZierGMD - German National Research Center for Information Technology

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Contents

– The Development of MPOA

– The Concept of MPOA

– The Implementation of MPOA and its Problems

– Practical Experience with MPOA

– Extensions of MPOA

– MPLS - an Alternative Approach to MPOA?

– Conclusion

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The Objective of MPOA

– The main goal of MPOA is the efficient transmission of unicast data between subnets in a LAN Emulation environment.

– The basic principle is the bypassing of routers by setting up ATM shortcuts between edge devices.

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The Development of MPOAStandardization Comittees

– MPOA is based on LAN Emulation over ATM and on the Next Hop Resolution Protocol

– ATM-Forum– LAN Emulation (LANE)

– Multi-Protocol over ATM (MPOA)

– IETF– Next Hop Resolution Protocol (NHRP)

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The Development of MPOAHistory

– 1995: 1st draft of the Control Signaling Working Group

– Two years discussion phase– imposed restrictions upon the original concept

(e.g., virtual router, multicast, QoS)– transfered specification work to the LANE/MPOA working group– objective: no modifications of existing systems

– 1997: Multi-Protocol Over ATM 1.0

– 1998: MPOA MIB 1.0

– 1999: Termination and Transfer– release of MPOA specification version 1.1

– authentification, MIB 1.0 und PICS– MPOA v1.1 Addendum on VPN Support– establishment of new ATM-IP Collaboration Working Group

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The Concept of MPOA

IngressMPS

MPOAResolutionResponse

IngressMPC

NHSEgressMPS

EgressMPCMPOA Shortcut

MPOAResolutionRequest

NHRP Resolution Request

NHRP Resolution Request

NHRP Resolution Response

NHRP Resolution Response

MPOACache Imposition

Request

MPOACache Imposition

Response

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MPOA - Architecture II

– Automatic discovery of MPC and MPS by extended LANE control messages– simple configuration

– discovery problems: some times several tries

– Variants of cooperation for MPS, MPC und LEC– normally manufacturer implement only one variant

– interoperability problems are foreseeable

– Varying implementations of control flow

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MPOA - Architecture I

Host

MPC

Host

LEC

MPC

LEC

LEC

MPC

LEC

Router

MPCMPC

MPS

MPCMPC

ELAN1 ELAN2

Router

MPCMPC

MPS

ELAN1

MPCMPC

MPS

ELAN2

Router Router

MPC

ELAN1 ELAN2

LEC LEC

Host

MPS MPS

ELAN1 ELAN2

ELAN1 ELAN2

ELAN1 ELAN2

MPS

MPC MPC

MPS

MPC MPC

FORENHRP

MPOAData

orPurge Messages

MPOA Keep-Alive

MPOA Control Messages

and MPOA Keep-Alive

MPOA Control Messages

Legend: Point-to-Point Point-to-Multipoint

Cisco

MPOA - Flow of Control

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MPOA - Shortcuts

– MPC detects data flow and sets up shortcut– Flow qualification: number of packets per second

– No shortcut for broadcast or multicast data

– Unidirectional and bidirectional shortcuts

– Internal shortcut between MPCs on same edge device are possible

– Great variety of transmission paths – complicates analysis of data loss and component malfunction

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MPCMPC

MPSNHS

case 4

MPCMPC

case 3

MPCMPC

case 2

MPCMPC

case 1

MPC

case 5

MPC MPC

case 6

MPC MPC MPC

MPS

MPOA - Shortcuts I

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MPOA - Security I

– Security risks– normal IP security devices can be bypassed, if the end system is

allowed to set up short cuts

– known security problems for ATM connection setup apply

– several MPSs on same router

– Some solutions– MPOA 1.1 Authentication Extension (MPC/MPS)

– Addendum for VPN Support

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MPOA - Security II

Legend: IP netshortcut allowedshortcut not allowed

MPS 3+4(filter defined)

ATM network

net

4

net

2

net 3net 5net 1 MPS 1+2(filter defined)

MPC4

MPC3MPC1

MPC2

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MPOA - Availability and Redundancy

– Redundant LANE server– LANE v2 LNNI Specification (ATM Forum, February 1999)

– Server Cache Synchronisation Protocol (SCSP), IETF 1998

– few implementations

– Redundant router– Virtual Router Redundancy Protocol (VRRP), IETF 1998

– few implementations

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MPOA - Management and Operation

– Management by SNMP– MIBs defined by ATM Forum and IETF

– proprietary MIBs (slow standardization process)

– Expensive management– lots of components (LANE server, router, switches)

– layer 2 (ATM/Ethernet switches) and layer 3 (router) management

– separate management of layers not efficient

– integrated management applications not available

– No tools for evaluation and configuration of flow qualification

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Practical Experience with MPOA IComponents

Functional entitiesof LANE and MPOA

Components from different manufacturers

Router/MPS/NHRP Cisco 4500FORE Powerhub 7000Cisco RSM on Catalyst 5505

LEC/MPC Cisco Catalyst 5505FORE Powerhub 7000FORE ES 3810PCs (NT 4.0/Windows 98, FORE ATM 155-Adapter)SUNs (Solaris 2.6, FORE ATM 622-Adapter)

LECS FORE ASX 1000FORE ASX 4000

LES/BUS Cisco Catalyst 5505FORE ASX 4000

FORE ASX 4000

LECS

LES/BUS - mpoa85

Cisco 4500MPS - mpoa83 / mpoa85

LEC - mpoa83 / mpoa85

MPS - mpoa82 / mpoa85

LEC - mpoa82 / mpoa85

Cisco LS1010

FORE ASX 1000

100 Mbps Ether

622 Mbps

Legend:

Cisco Catalyst 5505

LES/BUS - mpoa82/mpoa83

FORE ASX 1000

LECS

PC NT 4.0

mpoa83

Shortcut

155 Mbps

FORE ES 3810

LEC/MPC - mpoa82

PC Windows 98

mpoa82

LEC/MPC - mpoa83

FORE Powerhub 7000

GN Nettest

Example from the Test Scenarios

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Practical Experience with MPOA IIResults

– Interoperability problems between MPOA components of different manufacturers– partly resolved within test

– Communication between MPSs requires LANE

– Performance rates for workstations came up to expectation

– Performance rates for Ethernet switches didn’t come up to expectation– inefficient implementation of MPCs?

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Extensions of MPOA

– Support of Virtual Private Networks (VPN)– VPN-Identification for correct separation of VPNs

– released in October 1999

– Quality of Service Extension MPOA– MPOA only defined for UBR connections

– Extensions of QoS are being discussed

– open discussion about integrated or differentiated services

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MPLS - an Alternative Approach to MPOA?

– Multiprotocol Label Switching (MPLS) – drafts in discussion at IETF

– technique for WAN

– independent of physical networking layer (ATM, Frame Relay, Packet over Sonet, etc.)

– support of multicast transmission

– support of Quality of Service or Class of Service

– extension of normal IP routing by explicit routing

– traffic engineering

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Comparison of MPOA and MPLS

MPOA MPLSconnection setup data driven control drivenflow qualification packet per second no commitment: source or destina-

tion address, application (IP Port),VPN possible

networking tech-nique

ATM open (e.g., Ethernet, Packet overSonet, Frame Relay, ATM)

functional compo-nents

server (MPS), clients (MPC),router (NHRP), LANE server(LECS, LES, BUS)

router function

protocols LANE V2, NHRP,routing protocols

routing protocols

architectural model client / server independent componentsIP over ATM overlay model, separation of

router and ATM switchintegration of router and ATM switch

VPN VPN ID, Add on VPN support realization by Label Switched PathsQoS, CoS planned integrated, CoS-field in labelmulticast no support supportedavailability since two years soon, proprietary products available

(e.g., Cisco Tag Switching)

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Conclusion

– MPOA will not be a success– high complexity and as consequence high management costs

– new technologies provide simpler solutions than MPOA

– 802.1q (VLAN-trunking) for Fast and Gigabit Ethernet

– ATM to the desktop didn’t succeed

– routers based on ASICs route with full line rate (applies to 155 and 622 Mbps)

– MPLS will succeed in WAN– support of Traffic Engineering, QoS and Multicast