redistribution of iBGP routes into other routing protocols !!!!!

Mukarram Jah Raheel · ‎09-24-2009

Extract from MPLS VPN Architecture chapter 9....

"Contrary to the traditional BGP operation in which the internal BGP routes are not allowed to be redistributed into other routing protocols, this restriction is lifted in the MPLS/VPN environment. The VPN routes received by a PE router through an internal MP-BGP session from another PE router can be redistributed into other routing protocols."

Is it true .... kindly comment ???

jcozzupoli · ‎09-24-2009

This is true because some customers will chose to run such IGPs as RIPv2 as the PE-CE protocol on some sites (like small branch offices) and run BGP at their HQ. So within the SP network, there will be redistribution of routes advertised from the HQ (using BGP) into the SP core which will then need to be redistributed into the RIPv2 vpnv4 vrf address-family to the Brach CE, for the Branch CE to learn these networks their HQ wants them to know. This is just an example to explain to you better.

Mukarram Jah Raheel · ‎09-24-2009

my question was about the following statement:

"Contrary to the traditional BGP operation in which the internal BGP routes are not allowed to be redistributed into other routing protocols"

Giuseppe Larosa · ‎09-24-2009

Hello Mukarram,

this simply means that for MP BGP routes in af vpnv4 you don't need to explicitly allow redistribution of iBGP learned routes into an IGP.

see

http://www.cisco.com/en/US/docs/ios/iproute/command/reference/irp_bgp1.html#wp1014183

that is

bgp redistribute-internal

this is not needed in address-family vrf X to have iBGP learned routes redistributed into a PE-CE routing protocol.

this command is still needed in global routing table if you want to redistribute iBGP learned routes into an IGP.

Hope to help

Giuseppe