From: Treptow, Georg (gxtrept@xxxxxxxxx)
Date: Sat Jul 20 2002 - 18:11:35 GMT-3
Seems like the command does not stick when saving the command. When you
reboot the router it will disappear. I was able to use it successfully when
declaring my internal networks learned via IGP's but that were in different
AS's and therefore advertised via EBGP with an AD of 20 to take on an IBGP
metric of 200. Therefore recursive routing loops will be avoided.
Georg
-----Original Message-----
From: Anthony Pace [mailto:anthonypace@fastmail.fm]
Sent: Friday, July 19, 2002 12:54 AM
To: Treptow, Georg; 'David Luu'; tsiartas; 'Michael Popovich';
'chenyan'; 'ccielab'
Subject: RE: network backdoor
The BACKDOOR command will reduce the AD to 200 for the IGP routes which
it names. THis is needed because otherwise you will "saw off the branch
you are sitting on". If the EBGP peer got a route via an IGP and got
that route again via a BGP tcp session and preferred the BGP route it
would have no way of getting to the BGP peer announcing the route
becasue it just cut off it's own connectivity.
I can't get the BACKDOOR command to work, though. I have to resort to
using the Distance/neighbor/ACL command. Are there any caveats to the
BACKDOOR command?
Anthony Pace
On Sun, 14 Jul 2002 17:38:15 -0500, "Treptow, Georg"
<gxtrept@qwest.com> said:
> it is my understanding that the network backdoor command is assigned at
> EBGP
> peers to avoid having actual internal networks show up with an AD of
> 20.
> This command needs to be entered for every network you are receiving.
>
> Right or Wrong?
>
> Georg
>
> -----Original Message-----
> From: David Luu [mailto:wicked01@ix.netcom.com]
> Sent: Friday, July 12, 2002 4:04 PM
> To: tsiartas; 'Michael Popovich'; 'chenyan'; 'ccielab'
> Subject: RE: network backdoor
>
>
> for added clarity, it uses the local bgp distance of 200 and not the
> ibgp
> distance
>
> At 12:12 PM 7/12/2002 -0500, tsiartas wrote:
> >Was just reading the BGP configuration book.
> >the backdoor command makes the ebgp route to take the ibgp ADistance of
> >200, so it is not preferred in the routing table over other IGPs. That
> >all it does.
> >
> >h.
> >
> >-----Original Message-----
> >From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> >Michael Popovich
> >Sent: Friday, July 12, 2002 12:22 AM
> >To: 'chenyan'; 'ccielab'
> >Subject: RE: network backdoor
> >
> >I was under the impression that it would still advertise the network but
> >with an AD of 200.
> >
> >MP
> >
> >-----Original Message-----
> >From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> >chenyan
> >Sent: Thursday, July 11, 2002 11:27 PM
> >To: ccielab
> >Subject: network backdoor
> >
> >I used the network backdoor command, but it still can advertise the net
> >I configured with backdoor to other ebgp peers?
> >why?
> >Thanks.
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