On Jun 10, 2013, at 12:08 PM, Patrick W. Gilmore <patr...@ianai.net> wrote:

>> however, providers a/b at site1 do not send us the two /24s from
>> site b..
> 
> This is probably incorrect.
> 
> The providers are almost certainly sending you the prefixes, but your router 
> is dropping them due to loop detection. To answer your later question, this 
> is the definition of 'standard' as it is written into the RFC.
> 
> Use the allow-as-in style command posted later in this thread to fix your 
> router.


I've done this many places, and find allow-as-in can be, uh, problematic. :)  
Everyone says to just turn it on, but it's possible to get some strange paths 
in your table that way, in some circumstances.

For most users having a default route is just as good of a solution.  Each site 
will have a full table minus the small number of prefixes at the other site, 
and a static default will get packets to your upstream that has those routes.  
Don't like a default?  Just static the netblocks at the other side to a 
particular provider.  Already have a default because you weren't taking full 
tables?  You're good to go, no special config needed.

Of course it depends on what your site-to-site requirements are, if they are 
independent islands or talking to each other with critical data all the time.

-- 
       Leo Bicknell - bickn...@ufp.org - CCIE 3440
        PGP keys at http://www.ufp.org/~bicknell/





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