BGP multihoming question.

Thu Dec 9 14:23:16 UTC 2010

2010/12/9 b2 <b2 at playtime.bg>:
> Hi , first sorry for lame question but i'm new to BGP.
> In my ISP I have two full BGP sessions with my two transit providers (X
> and Y), and for every provider i have assigned PA (Provider
> Aggregatable) networks. Is it possible (if there are no filters on other
> side) to advertise X networks to Y and Y to accept them ? My confusion
> comes from the PA status , i know if it is PI there are no problem to
> route it to any AS.

Generally speaking, you need at least a /24 from one or the other of
them, you need a letter of authorization (LOA) from the one that
provided the /24 permitting you to announce it to other ISP(s) and
you'll need to test to make sure the ISP who assigned the /24 has set
up their filters properly so that you can communicate with them over
the Internet even when your line to them is down.

For your first foray in to BGP, I strongly advise you to contract an
expert for help both programming your router and interacting with your
ISPs.

Regards,
Bill Herrin

-- 
William D. Herrin ................ herrin at dirtside.com  bill at herrin.us
3005 Crane Dr. ...................... Web: <http://bill.herrin.us/>
Falls Church, VA 22042-3004