This is due to the fact that paths via transit area ABRs other than the virtual link endpoints can be installed. If I were designing a link-state protocol from scratch, I would not include the complexity of virtual links as they are specified in OSPF.
Hope this helps, Acee On Nov 14, 2010, at 9:47 PM, p6 c6d6 wrote: > hi, > > why should one recalculate routes using transit areas summary lsas, even if > better paths exist through transit area. as a virtual link is considered as > an unumbered p2p link, it is as good as the router has an interface to the > backbone. > referring to rfc2328 figure 17, RT1 chooses route network N1 through RT4, > since that > is an intra-area path, that is in accordance to the path preference rules of > ospf. > why do we give special treatment for transit areas. If the link were not a > virtual-link and > if it indeed is real p2p interface in to the backbone, we will not try to > route the data to N1 > through RT5, since the route through RT4 would be preferred. why special > treatment for > transit areas, and why can't we extend this treatment to other areas as well > (neglecting > the fact that area routing is protected by bad routing of other areas). > > thanks in advance > > > <ATT00001..txt> _______________________________________________ OSPF mailing list [email protected] https://www.ietf.org/mailman/listinfo/ospf
