From: Rob Webber (rwebber@xxxxxxxxxxxx)
Date: Fri Feb 09 2001 - 23:52:40 GMT-3
The only thing I can think of is the default-originate has a route-map
keyword. You could use this to specify a route-map, then have the route-map
match the route that determines whether you originate the default route.
However this would only control whether router B generates a default route,
not whether router A accepts it:
Router B should generate a default route if it has a route to
192.168.10.0/24:
hostname B
!
router bgp 65000
neighbor (routerA) default-originate route-map mymap
network 192.168.10.0
!
route-map mymap permit 10
match ip address prefix-list mylist
!
ip prefix-list 10 permit 192.168.10.0/24
Good luck, Rob.
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
Dan
Sent: Thursday, February 08, 2001 2:38 PM
To: Johnny Dedon; ccielab@groupstudy.com
Subject: Re: Route Policy Question...
Hmm...I don't know. Local pref would discriminate between the "same" route
learned from different sources, but this is talking about accepting default
based on a whether or not a certain route (x.x.x.x/x)exists in the routing
table.
I think I would need to use a filter to conditionally filter the default
route with a route map in order to not accept it at all unless I have a
"match" ( x.x.x.x/24 via x.x.x.x) in the routing table. Simply altering
local pref would stop it from entering the routing table, but it would still
be in the BGP table and I think "not" accepting it implies to filter it from
entering the BGP table as well.
Something like:
router bgp x
neighbor x.x.x.x route-map ASx-bgp-in in
Then conditionally filter the default in the route map.
I obviously haven't figured out what to "match"
That's just how I interpreted it.
Dan Pontrelli
----- Original Message -----
From: "Johnny Dedon" <johnny.dedon@exodus.net>
To: "Dan" <dp595@optonline.net>; <ccielab@groupstudy.com>
Sent: Thursday, February 08, 2001 12:28 PM
Subject: Re: Route Policy Question...
> Dan,
> I believe this question assumes that Router A is receiving the route via
> another connection under normal circumstances. If this route dissapears,
> then it should accept a default from router B.
> You can use the local preference attribute to make the route coming from
> router b less preferred under normal conditions but it will use it if it
> does nto have a mor preferred route. Halabi has lots of examples of this
> type in his book.
>
> Johnny Dedon
> Senior Staff Consultant
> Exodus Professional Services
> johnny.dedon@exodus.net
> www.exodus.net
> ----- Original Message -----
> From: "Dan" <dp595@optonline.net>
> To: <ccielab@groupstudy.com>
> Sent: Wednesday, February 07, 2001 5:50 PM
> Subject: Route Policy Question...
>
>
> > I have seen several practice questions asking to implement a policy that
=
> > performs a certain action based on whether or not a certain route exists
=
> > in the routing table. For example:
> >
> > Configure a BGP policy for RouterA to accept a default route from Router
=
> > B only if RouterA is learning a route to x.x.x.x/x from RouterB
> >
> > I assume we would put "default-originate" under the BGP process of =
> > RouterB, but I have know idea how to set up this policy on RouterA.
> >
> > Any advice?
> >
> > Thanks,
> >
> > Dan Pontrelli
> >
> >
> >
> >
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