same bgp AS number at all brach locations

deshpande-s · ‎12-02-2008

hello friends,

please tell me, if i use same bgp AS number for all branch locations then what will be routing issues, i will get?

milan.kulik · ‎12-03-2008

Hi,

it's not clear what you mean.

Establishing one AS and running iBGP between all your sites?

Or running a (provider) MPLS backbone with the same AS number assigned to all sites?

(In this case neighbor allowas-in would help, see http://www.cisco.com/en/US/docs/ios/12_0t/12_0t7/feature/guide/VPN_EN.html#wp1045854)

BR,

Milan

Giuseppe Larosa · ‎12-03-2008

Hello Sourabh,

just a little add to Milan's post:

if you use a Service Provider MPLS L3 VPN this is not an issue: the service provider network can perform AS override of the private AS (64512-65535 range) that it has given to your company.

If you use iBGP and you own your own WAN infrastructure (or you have bought a L2 service) this is not a problem too but you may need to deploy BGP Route Reflector in order to have the routes to propagate in all the domain without using a full mesh of iBGP sessions.

Hope to help

Giuseppe