BGP advertise-best-external on RR

[mkamal at noor.net (Mohamed Kamal)]

Hi,

I have a classic network design with 3 gateways, each receive a default 
route from different upstream provider. Each gateway has a BGP session 
with a route-reflector, which in turns reflects the best BGP route to 
the other PE routers in the network. The route-reflectors are running 
the SRE train (12.2(33)SRE1) and here exist the problem.

I need to leak all the default routes (3 default routes) from the 
gateways into the PE routers. I have done this via bgp 
advertise-best-external on the gateways. So far, the default routes 
exist on the route-reflector, however it's suppressed as the RR will 
only send the best path.

I have configured bgp advertise-best-external also on the RR but it 
didn't work, because the RR didn't see that the different default routes 
received are of "external" type. Cisco didn't state that clearly and it 
only stated that bgp best external feature won't work on the RR unless 
you get an ASR loaded with an IOS-XE 3.4 or later!

Anyhow, do anyone here has a suggestion of how to get this done without 
replacing my RR sticking to this classical network design?

Thanks.

-- 
Mohamed Kamal
Core Network Sr. Engineer