[Isis-wg] Clarification needed on domain-wide prefix distribution

[Quaizar Vohra]

In case of external routes with internal metric type, one can update
the advertised prefix when leaking the route from L1 into L2 to
account for the cost of path from L1/L2 router to the originating
router. 

With external metric type this is a problem.

Well domain-wide prefix distribution draft seems not to preclude
external routes from being originated in L1. Section 3.0 rule 1)
says "Only L1 intra-area prefixes and external prefixes are
redistributed from L1 into L2".

 > Folks,
 > I am surprised to know that there can be L1 external routes also.
 > I thought that only L2 routers can advertise the external routes.
 > If there are L1 external routes, then how does a router in L2
 > knows about the advertising router present in L1 domain for 
 > calculating the metric. I do not see equivalent of OSPF type 4
 > summary LSA in IISIS.
 > Also the domain-wide prefix distribution draft talks about 
 > the following types of routes.
 > - L1 intra-area
 > - L2->L1 inter-area
 > - L2->L1 external
 > - L2 intra-area
 > - L2 external
 > - L1->L2 inter-area
 > and each can be distinguished according to the table given
 > in the draft. 
 >  
 > Is there any proposal to have L1 external routes and redistribution
 > of such routes into L2? 
 > 
 > Thanks,
 > Rajesh
 > 
 > _______________________________________________
 > Isis-wg mailing list  -  Isis-wg@external.juniper.net
 > http://external.juniper.net/mailman/listinfo/isis-wg