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From: Vijay Nath (iproutingREDIFFMAIL.COM)
Date: Tue Feb 19 2002 - 22:52:09 CST
Do ignore previous mail..
I would have phrased my question properly or more appropriately?.My question is more specific to the RFC 2328 sec 2.3.
"This section has assumed that packets destined for external destinations are always routed through the advertising AS boundary router. This is not always desirable. For example,suppose in Figure 2 there is an additional router attached to Network N6, called Router RTX. Suppose further that RTX does not participate in OSPF routing, but does exchange BGP information with
the AS boundary router RT7. Then, Router RT7 would end up advertising OSPF external routes for all destinations that should be routed to RTX. An extra hop will sometimes be introduced if packets for these destinations need always be routed first to Router RT7 (the advertising router)"
It looks like RTX is part of same domain but it doesn't not participate OSPF but shares BGP info with ASBR (*not* directly to another BGP router in another DOMAIN).This was my understanding. Is your answer still valid to this ??
And Same section Last para:
The "forwarding address" has one other application. It enables routers in the Autonomous System's interior to function as "route servers". For example, in Figure 2 the router RT6 could become a route server, gaining
external routing information through a combination of static configuration and external routing protocols.
I assumed RT6 will *dynamically* become route server.SO IT is only *ADMINISTRATIVE* thing??. Am i right?
Thanks for replying,
On Tue, 19 Feb 2002 Alex Zinin wrote :
> This is the way routing in the Internet works.
> Autonomous systems exchange routing information using
> BGP. So, in this case, RTX is a BGP speaker in another
> AS and that's why it does not participate in the OSPF
> domain that the ASBR belongs to.
> It is also a good idea to add that redistributing BGP
> information in BGP is considered to be bad practice
> and you'll see no ISP of a considerable size doing
> Regarding "route servers". Route redistribution, and
> wether a router becomes a "route server" is an
> decision. Again, I've never seen an OSPF ASBR being
> as a "route server", if anyone has, it would be
> to hear about the product and setup...
> Alex Zinin
> Sunday, February 17, 2002, 8:00:08 PM, Vijay Nath wrote:
> > I have two doubts in sec 2.3 of RFC 2328
> > 1. RFC assumes IF there is a additional router
> > next to a ASBR, Which DOESN'T participate in OSPF
> > routing but share BGP info with a ASBR.
> > Could any one explain the real purpose of additional
> > router RTX , say if deployed in OSPF domain?. In what
> > way it is helpful to share BGP info?.
> > 2. Forwarding address enables routers in AS's to act
> > "route servers"
> > On what basis a router become a "route server"??.
> > Thanks,
> > V Nath