RES: [c-nsp] adjusting AD based on route tag/community?

[Murilo Antonio Pugliese]

I think that, if you have a MPLS backbone, you may achieve this (constraint-based routing)
deploying MPLS Traffic Engineering, which replicate and expand the TE capabilities of 
Layer 2 ATM and Frame Relay networks, support a high use of transmission capacity, and 
provide link or node failure resilience

Yours Truly.

Murilo Pugliese
Diveo do Brasil Telecomunicações Ltda


-----Mensagem original-----
De: Andrey A. Ryazanov [mailto:sg at di-net.ru]
Enviada em: quinta-feira, 16 de junho de 2005 04:07
Para: Rainer Clasen; Discussion for Network Service Provider
Assunto: Re: [c-nsp] adjusting AD based on route tag/community?


You can adjust AD locally

router bgp 12345
distance bgp 180 200 200

router ospf 1
distance 110

You can't propagate AD via routing protocols to other routers.

You can't alter AD via route-maps.

You can't avoid more specific routing policy.

Well ... there's no luck in this life :D

P.S. There're certainly some well-known methods exist to resolve your problems. Just 
specify what exactly your problems are.

Cheers! ;)

Andrey Ryazanov
Digital Network JSC
+7 095 723 8332 ext. 203

---------- Original Message -----------
From: bj at zuto.de (Rainer Clasen)
To: Discussion for Network Service Provider <cisco-nsp at puck.nether.net>
Sent: Tue, 14 Jun 2005 16:14:56 +0200
Subject: [c-nsp] adjusting AD based on route tag/community?

> Hello,
> 
> rethinking some of our setups I'm currently wondering if there is a way
> to adjust the administrative distance of routes learned through OSPF/BGP.
> 
> That'd help me in certain scenarios:
> - mutual redistribution, prefering some routes on each redistribution
>   point
> - two level backups (i.e. if primary link and first backup fails, kick in
>   the second one)
> - initiating callback for a backup dialin on router A, while the client
>   calls you on router B
> 
> The Idea is to have some special backup routes configured with a tag. This
> tag is propagated through OSPF or BGP and used to set the AD on the other
> routers. (OT: reading juniper docs I got the impression, you can play such
> dirty tricks with the color)
> 
> I've also tried to abuse BGP weights for this, but had no luck. If you
> redistribute routes into BGP, you have to set their AD > 200 to give BGP
> the chance to override them. On the other hand you have to set the AD <
> 200 if you want a newly installed route to be considered for installation
> if there is a BGP route active ...
> 
> Somehow I'd like to avoid using more-specific routes for the primary link
> to overrule all backups ...
> 
> Rainer
> 
> -- 
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------- End of Original Message -------

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