Did MPOA achieve its objective? TERENA Networking Conference 2000 Lisbon, Portugal May 2000 Ferdinand Hommes, Eva Pless, Lothar Zier GMD - German National Research Center for Information Technology

2 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

3 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.

4 The Development of MPOA Standardization 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)

5 The Development of MPOA History –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

6 The Concept of MPOA Ingress MPS MPOA Resolution Response Ingress MPC NHS Egress MPS Egress MPC MPOA Shortcut MPOA Resolution Request NHRP Resolution Request NHRP Resolution Response MPOA Cache Imposition Request MPOA Cache Imposition Response

7 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

8 MPOA - Architecture I Host MPC Host LEC MPC LEC MPC LEC Router MPC MPS MPC ELAN1ELAN2 Router MPC MPS ELAN1 MPC MPS ELAN2 Router MPC ELAN1ELAN2 LEC Host MPS ELAN1ELAN2 ELAN1ELAN2 ELAN1ELAN2

MPS MPC MPS MPC FORENHRP MPOA Data or Purge 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

10 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

11 MPC MPSNHS case 4 MPC case 3 MPC case 2 MPC case 1 MPC case 5 MPC case 6 MPC MPS MPOA - Shortcuts I

12 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

13 MPOA - Security II Legend: IP net shortcut allowed shortcut not allowed MPS 3+4 (filter defined) ATM network net 4net 2 net 3net 5net 1 MPS 1+2 (filter defined) MPC4 MPC3MPC1 MPC2

14 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

15 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

16 Practical Experience with MPOA I Components

FORE ASX 4000 LECS LES/BUS - mpoa85 Cisco 4500 MPS - mpoa83 / mpoa85 LEC - mpoa83 / mpoa85 MPS - mpoa82 / mpoa85 LEC - mpoa82 / mpoa85 Cisco LS1010 FORE ASX 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

18 Practical Experience with MPOA II Results –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?

19 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

20 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

21 Comparison of MPOA and MPLS

22 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