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Phased OSPF Link-State Database Synchronization draft-dimitri-ospf-phased-db-sync-00.txt

Phased OSPF Link-State Database Synchronization draft-dimitri-ospf-phased-db-sync-00.txt. Dimitri Papadimitriou Alcatel-Lucent IETF 79 – Beijing November 7-12, 2010. Motivation. Opaque LSAs

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Phased OSPF Link-State Database Synchronization draft-dimitri-ospf-phased-db-sync-00.txt

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  1. Phased OSPF Link-State Database Synchronizationdraft-dimitri-ospf-phased-db-sync-00.txt Dimitri Papadimitriou Alcatel-Lucent IETF 79 – Beijing November 7-12, 2010

  2. Motivation • Opaque LSAs • OSPF extensibility: information contained in Opaque LSAs often used by application wishing to distribute information throughout OSPF domain (so called "non-IP routing information") • Standard OSPF flooding mechanisms used to distribute Opaque LSAs [RFC2370] • OSPF [RFC2328] mandates that neighbor is in Full state and the two routers are fully adjacent only when LSDB synchronization is completed • Motivation: prevent delaying establishment of full adjacency b/w two routers (Full state) resulting from time needed to synchronize Opaque LSAs Occurs when #Opaque LSAs >> #non-Opaque LSAs

  3. LSDB Synchronization (current) RFC 2328 + RFC 2370 A B 8 7 6 5 4 3 2 1 LSA Type 1|2|3|4|5|7 h g f e d c b a h g f e d c b a Opaque LSA Type 9|10|11 1,2,3,4,5,6,7,8 OSPF-Transport Instance 4 3 2 1 g f e b g f e b Opaque LSA Type 9|10|11 Step 2: 1,2,3,4 4 3 2 1 h d c a h d c a LSA Type 1|2|3|4|5|7 Step 1: 1,2,3,4

  4. LSDB Synchronization (this draft) This draft 8 7 6 5 4 3 2 1 h g f e d c b a h g f e d c b a Opaque LSA Type 9|10|11 LSA Type 1|2|3|4|5|7 Step 1: 1,3,4,8 Step 2: 2,5,6,7 This draft A B 8 7 6 5 4 3 2 1 Opaque LSA Type 9|10|11 g f e b g f e b h d c a h d c a LSA Type 1|2|3|4|5|7 Step 1: 1,2,3,4 Step 2: 5,6,7,8

  5. Bottomline • This draft reverts back to RFC 2328 the LSDB synchronization process that was extended by RFC 2370 • Remember RFC 2370 LSDB synchronization includes both non-Opaque and Opaque LSAs • LSDB synch phasing achieved by logically segmenting LSDB sync process add "on top of" the LSDB synchronization process (per RFC 2328) a synchronization process dedicated to Opaque LSAs

  6. LSDB Synchronization Process Compared to RFC 2370, Phased LSDB sync exchange process works as follows: Opaque LSAs are included in LSDB summary list sent to the neighbor iff i) The neighbor is Opaque capable (see [RFC2370]) ii) The neighbor has fully exchanged router-LSAs, network-LSAs, summary-LSAs (contained in the area structure), AS-external-LSAs (contained in the global structure), and Not-So-Stubby Area (NSSA) LSAs: Full state has been reached iii) Both local and neighbor router supports the phased LSDB synchronization

  7. Per RFC 2328 • ExStart, Exchange, Loading and Full states are defined per [RFC2328] • Events NegotiationDone, ExchangeDone and LoadingDone are defined per [RFC2328] • Reaching Full State, OSPF can perform all subsequent operations per [RFC 2328] including • computation of shortest-path tree for an area per [RFC2328] • computation of AS external routes per [RFC2328]

  8. Phased Link-State Database (LSDB) Synchronization Process In case Full state is reached • Start_O: LSDB contain Opaque LSA's AND capability successfully negotiated • NExchange_O: • lists the content of its Opaque area LSDB (Type 9, 10, 11 LSA) in the neighbor DB summary list • router sends DD packets for these Opaque LSAs to the neighbor • NExchangeDone_O: both routers have successfully transmitted a full sequence of DD packets • Loading_O: LS Request packets sent to the neighbor asking for more recent Opaque LSAs discovered (but not yet received) in NExchange_O state • LoadingDone_O: LS Updates have been received for all out-of-date portions of Opaque LSDB • Full_O: Opaque LSA exchange completed

  9. Backward Compatibility • Phased LSDB synchronization process is backward compatible since • this draft extends the current process if and only if it is locally (see Section 4.2) and remotely supported (see Section 4.3) • If either of these conditions is not met LSDB synchronization falls back to the process currently specific per [RFC2370] • This draft does not modify the LSDB process as specified in [RFC2328] • Routers may be required to support both methods

  10. Next Steps • Interest in progressing this document at OSPF WG ?  Poll request for WG Document

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