From: Carlos G Mendioroz (tron@huapi.ba.ar)
Date: Fri Aug 27 2004 - 15:07:12 GMT-3
AFAIK, there is no technical problem in advertising the same prefix from
different ASs. BGP uses the AS path to do loop prevention (and path
selection in some implementations :-) but no problem in having the same
prefix from many places.
Jeff Nelson wrote:
> To be more specific (and after doing more research), can one advertise
> to an ebgp neighbor a more specific route of a supernet it is learning
> from the same neighbor? What if it is an identical route? I assume you
> would have to filter it with a prefix list.
>
> I realize this is not best practice anycast BGP and that RFC 1930
> suggests on prefix one AS, but... how would it be done?
>
> thanks,
> jeff
> Jeff Nelson(jnelson@rackspace.com)@04/08/27 10:43:
>
>>Say you're advertising a /20 from one AS. You want to take a /24 from
>>that and advertise it from another AS--I believe this is an "anycast"
>>solution for BGP created redundancy. When that /24 is created on the
>>other AS, it does not advertise it to its EBGP peer. Do I have this all
>>wrong? It would seem that since the router is receiving a /20 from the
>>other AS via EBGP, it won't advertise a subset of that to the same
>>neighbor. I though you could as long as it wasn't the same exact route.
>>
>>??? any ideas ???
>>--
>>jeff
>>
>>_______________________________________________________________________
>>Please help support GroupStudy by purchasing your study materials from:
>>http://shop.groupstudy.com
>>
>>Subscription information may be found at:
>>http://www.groupstudy.com/list/CCIELab.html
>
>
-- Carlos G Mendioroz <tron@huapi.ba.ar>
This archive was generated by hypermail 2.1.4 : Fri Sep 03 2004 - 07:02:49 GMT-3