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Protocol Topology Support Protocol Topology Support for IS-ISfor IS-IS
Kay Noguchi <[email protected]>
draft-ietf-noguchi-isis-protocol-topology-01.txt
56th IETFSan Francisco, CA, USA
March 18, 2003
Copyright © 2003 IP Infusion Inc. All Rights Reserved.
ContentsContents
• RFC 1195 Restrictions• Goal• New TLV and Sub-TLV• Adjacency Formation• LSP Encoding• SPF Calculation• Migration Mechanism
Copyright © 2003 IP Infusion Inc. All Rights Reserved.
RFC 1195 RestrictionsRFC 1195 Restrictions
• Every router MUST be capable of all network layer protocols that are present in an area.– Can’t mix IPv4 only and IPv6 only routers
• Protocol Support capability MUST be identical on all interfaces. – Node oriented protocol support capability
Copyright © 2003 IP Infusion Inc. All Rights Reserved.
GoalGoal
• IPv4 only, IPv6 only and IPv4/IPv6 dual routers can co-exist.– By maintaining different SPF trees for each
network layer protocols.
• Different protocol support capability on each Interface– Interface oriented protocol support
capability
Copyright © 2003 IP Infusion Inc. All Rights Reserved.
New TLV and Sub-TLVNew TLV and Sub-TLV
• Interface Protocols Supported TLV– Encoded in IS-IS Hello.– Convey interface oriented protocol support
capability to neighboring routers.• Protocols Supported Sub-TLV
– Encoded in Extended IS-Reachability TLV.– Flood interface oriented protocol support
capability in the area.
Copyright © 2003 IP Infusion Inc. All Rights Reserved.
Adjacency FormationAdjacency Formation
• MUST drop IS-IS Hello which doesn’t contain Interface Protocols Supported TLV.– To avoid possible routing loop.
• Point-to-Point Interfaces– MUST NOT form an adjacency if at least one of
the same protocol capability is not met with neighboring router.
• Broadcast Interfaces– MUST attempt to form an adjacency regardless of
the neighbor’s protocol capability.• No change in DIS election.
Copyright © 2003 IP Infusion Inc. All Rights Reserved.
LSP EncodingLSP Encoding
• Use Protocols Supported Sub-TLV.• Point-to-Point Interfaces
– ANDing local and remote side of protocol support capability.
• Broadcast Interfaces– Regular LSP
• Local side of protocol support capability
– Pseudo-Node LSP• Remote side of protocol support capability
Copyright © 2003 IP Infusion Inc. All Rights Reserved.
SPF CalculationSPF Calculation
• SPF MUST be calculated separately for each network layer protocol.
• New Protocol Supported Sub-TLV MUST be used instead of old Protocols Supported TLV.– Reverse protocol support check is not
“MUST” because pseudo-node LSP also contains Protocol Supported Sub-TLV.
Copyright © 2003 IP Infusion Inc. All Rights Reserved.
Migration MechanismMigration Mechanism
1) Start to advertise new TLV and Sub-TLV in addition to the old TLV.
2) Change adjacency formation and SPF calculation based on this draft.
3) Stop to advertise old TLV.
4) Change interface protocol support capability appropriately.
Copyright © 2003 IP Infusion Inc. All Rights Reserved.
Questions?Questions?
Copyright © 2003 IP Infusion Inc. All Rights Reserved.
Questions to M-ISISQuestions to M-ISIS
• Non M-ISIS IPv4 router and M-ISIS IPv6 router.– How to make adjacency?
• Non M-ISIS IPv4/IPv6 dual router and M-ISIS IPv4/IPv6 dual router.– Possible routing loop?
• IPv6 Reachability TLV and MT Reachable IPv6 Prefixs(M-ISIS).– Do we need both?
