Hi Richard, Sorry for the late reply!
Yes, this is a problem with the current spec. We incorrectly convinced ourselves that such a check is not required. Here's the proposed change. We make sure the non-DR router have a synchronized database with the DR before advertising the Type 1 link to other non-DR router. We declare the DR as a fully synchronized adjacency after having all the DR's LSA request satisfied (i.e., Our LSA update for the LSA requests are acknowledged by the DR.) in addition to having a full adjacency with the DR. The rule then will look like the following: o If a router is not the DR and has a fully synchronized adjacency to the DR, it MUST add a Type 1 link corresponding to each neighbor that is in state 2-Way or higher. Tanks, Lili -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Richard Ogier Sent: Tuesday, May 17, 2011 12:05 PM To: [email protected] Subject: Re: [OSPF] OSPF Hybrid Broadcast and P2MP Interface Type Section 3.6 of draft-nsheth-ospf-hybrid-bcast-and-p2mp-01 has the following rule: o If a router is not the DR and has a full adjacency to the DR, it MUST add a Type 1 link corresponding to each neighbor that is in state 2-Way or higher. Suppose i and j are non-DR routers. It seems to me that i should also require that the DR's router-LSA include a link to j before i adds a Type 1 link corresponding to j, in order to ensure that i and j are fully synchronized before either uses the other as a next hop. Is there a reason why this condition was omitted? To explain further, the SPT calculation (Section 16.1 of RFC 2328) requires that router j advertise a link back to router i before i can use j as a next hop (and vice versa). Thus, routers i and j can use each other as a next hop if they both advertise a link to each other. Therefore, the above rule from draft-nsheth only ensures that routers i and j are fully adjacent with the DR before either can use the other as a next hop. As a result, the DR might not be fully adjacent with router i or j, and thus i and j may not be fully synchronized. Note that full adjacency with a neighbor does not imply that the link state databases are synchronized (see footnote 23 in RFC 2328). It only means that the router is at least as up-to-date as the neighbor, since it only means that all Link State Requests have been satisfied. Please correct me if I am mistaken. Richard _______________________________________________ OSPF mailing list [email protected] https://www.ietf.org/mailman/listinfo/ospf _______________________________________________ OSPF mailing list [email protected] https://www.ietf.org/mailman/listinfo/ospf
