Subject: draft-ietf-l3vpn-ospf-2547-01.txt query

From: "Karthikeyan Subramaniam" <[email-masked]>
Date: 30 Apr 2004 12:49:02 -0000

Hello,

    As stated in the draft draft-ietf-l3vpn-ospf-2547-01.txt,

   "Per [VPN], the VPN routes are distributed among the PE routers by
   BGP.  If the PE uses OSPF to distribute routes to the CE router, the
   standard procedures governing BGP/OSPF interactions [OSPF] would
   cause routes from one site to be delivered to another as AS-external

   routes (in type 5 LSAs).  This is undesirable; it would be much
   better to deliver such routes in type 3 LSAs (as inter-area routes),
   so that they can be distinguished from any "real" AS-external routes
   that may be circulating in the VPN. (That is, so that they can be
   distinguished by OSPF from routes which really do not come from
   within the VPN.)"

   So the query is why do we need to distinguish As-external routes from inter-area routes from VPN perspective??? (I guess Type-3 LSAs are generated for proper database synchronization from OSPF perspective, is there any other reason???)

Thanks in advance
S.Karthikeyan

---

From: Anand Oswal <[email-masked]>
Date: Fri, 30 Apr 2004 09:31:59 -0700

Karthikeyan,

The remote CE routers of the same VPN, need to appear as if they are
part of the same OSPF domain, that is why we carry Type 1,2,3 LSAs
as Type 3.

If you carry all your routes as AS External, how would you know which
ones
are the "real" Ext routes 

Thanks
Anand