Re: Single AS multiple Dirverse Providers

[Leo Bicknell <bicknell () ufp org>]

On Jun 10, 2013, at 12:08 PM, Patrick W. Gilmore <patrick () 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 - bicknell () ufp org - CCIE 3440
        PGP keys at http://www.ufp.org/~bicknell/

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