From: Michael Davis (miked@xxxxxxxxxx)
Date: Fri Mar 02 2001 - 15:17:58 GMT-3
It will work if the filter is only on outbound updates to neighboring ASes.
----- Original Message -----
From: "Mark Salmon" <masalmon@cisco.com>
Cc: <ccielab@groupstudy.com>
Sent: Friday, March 02, 2001 11:28 AM
Subject: Re: BGP problem
> No, that will not work as if one of the links go down, (say on r1), then
r2 will
> not send to r1 via IBGP the routes it learned from its EBGP peer.
>
> "David T. Absalom" wrote:
>
> > I believe you could use a outgoing route map for the ebgp sessions on r1
and
> > r2 to only allow local routes be advertised, i.e.
> >
> > ip as-patch access-list 1 permit ^$
> >
> > route-map notransit permit 10
> > match as-path 1
> >
> > This would only allow routes from AS1100 to be advertised via ebgp.
> >
> > Hope this helps...
> >
> > dave
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
> > Mark Salmon
> > Sent: Friday, March 02, 2001 9:42 AM
> > To: ccielab@groupstudy.com
> > Subject: BGP problem
> >
> > I have a BGP issue I want to bring to the group.
> >
> > as500 --------ebgp------as600
> > | |
> > | |
> > ebgp ebgp
> > | |
> > | |
> > r1:as1100--------ibgp-----r2:as1100
> >
> > I need r1 to use as500 exclusively as its exit and entrance as well as
> > r2 must use as600 exclusively as its entrance and exit. However, if the
> > links between r1 and as500 is lost, it must reroute through r2 to
> > as600. The same applies to r2. No load balancing is necessary. That
> > is not the problem, I am OK with setting up local preferences etc.
> >
> > The problem is, I do not want as1100 to be a transit as for Internet
> > routes.
> >
> > My idea is to use community lists and no export option from r1 to as500
> > as well as r2 to as600. I used ip as-path access lists and that is
> > where the problem starts. I do not see the as1100 routes on as500 or
> > as600 routers
> >
> > Here is my config on one router (it is virtually identical on the other
> > router):
> >
> > . router bgp 1100
> > network 192.168.1.0
> > network 192.168.3.0
> > neighbor 192.168.2.2 remote-as 1100
> > neighbor 192.168.25.2 remote-as 500
> > neighbor 192.168.25.2 send-community
> > neighbor 192.168.25.2 route-map nointernet out
> > !
> > ip classless
> > ip as-path access-list 1 permit _1100_
> >
> > route-map nointernet permit 10
> > match as-path 1
> > set community no-export
> >
> > --
> >
> > Mark Salmon
> > Network Support Engineer - SBC OP HQ
> > Cisco Systems Inc
> > 8735 W. Higgins Road Suite 300
> > Chicago IL 60631
> > Phone:773-695-8235
> > Pager:800-365-4578
> > email: masalmon@cisco.com
> > Empowering The Internet Generation.
> >
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