1 Multi Topology Routing for OSPFv3 (draft-mirtorabi-mt-ospfv3-00.txt) Sina Mirtorabi

222 Agenda MTRv3 Goal Potential Solutions Proposed Solution Default topology New LSAs MT-ID MT routing operations Backward compatibility

333 MTRv3 Goal Define multiple independent topology within a physical topology  Traffic separation across the network, an enterprise where different entities requires traffic separations  Use some links only for some type of traffic such as low delay

444 Potential Solutions Using Different Instance IDs  Use Instance IDs in the range of an AF (draft-ietf- ospf-af-alt-00.txt) to have multiple topologies. Scaling issues due to multiple adjacencies, databases etc.. Using an integrated approach with existing LSAs  Possible to replicate link descriptions in router- LSA for MTR. Issues with backward compatibility  Still doesn’t solve a need to associate prefixes with different topologies

555 Proposed Solution Define new LSAs to carry MT information New LSAs will be ignored by old routers, so no backward compatibility issues New LSAs are being defined in a TLV style, so that they can also facilitate any future extension in OSPFv3

666 Default Topology Default Topology is the topology that is built by using the existing LSAs as specified in OSPFv3 Other non-default topologies are built by using the new LSAs Possibility to use new LSA for default topology when all routers are MT capable For that a configurable parameter RFC2740Compatibility is used to control the generation of existing or new LSAs for default topology

777 New LSAs LSA Function codeLS Type Description 10xB001E-Router-LSA 20xB002E-Network-LSA 30xB003E-Inter-Area-Prefix-LSA 40xB004E-Intra-Area-Router-LSA 50xD005E-AS-External-LSA 60xB006E-Group-Membership-LSA 70xB007E-NSSA-LSA 80x9008E-Link-LSA 90x3009E-Intra-Area-Prefix-LSA US2S1TLSA Function Code

888 New LSAs (cont) New LSA payloads are TLV based TLV may contain sub-TLVs, this is explicitly indicated by setting a S bit E-Router LSA has link description TLV, describing link adjacencies. A Sub-TLV under each link description carries MT information Prefix LSAs has TLV under each Address Prefix carrying MT information (MT-ID and corresponding cost)

999 E-Router-LSA LS AgeLS type Link State ID Advertising Router LS sequence number LS checksumLength W V E B Options TLV typeTLV length Link-type0 Interface ID Neighbor Interface ID Neighbor Router ID Sub-TLVs

10 E-Intra-area-prefix-LSA LS AgeLS type Link State ID Advertising Router LS sequence number LS checksumLength #PrefixReferenced LS type Referenced Link State ID Referenced Advertising Router Prefix-Block lengthPrefixLength0 Address Prefix TLVs

11 E-Inter-area-prefix-LSA LS AgeLS type Link State ID Advertising Router LS sequence number LS checksumLength Prefix-Block lengthPrefixLength0 Address Prefix TLVs

12 MT-ID Fields 8 bit MT-ID field present in various LSAs MT-ID is accompanied with a MT-ID Metric field which carries a metric specific to a MT MT-ID value 0 is reserved for carrying information about Default Topology in the new LSAs

13 MT routing operations A Single adjacency is formed even if the link participates in multiple topologies OSPFv3 control packets are sent using IPv6 link local address which is MT independent Each topology’s SPT is calculated by using only MT-ID links and associated metric for that topology Network LSA is shared by all topologies During intra-area / Inter-area / external route calculation for a topology, only prefix belonging to a given MT with their associated metric are considered

14 Backward Compatibility An MT capable router will interact (in Default Topology) with non-MT capable routers by using the existing LSAs When all routers are MT capable, RFC2740Compatibility can be set to disable and only extended LSAs are used for Default Topology

15 We would like draft-mirtorabi-mt-ospfv3-00.txt to be accepted as a OSPF WG document