Learn and Advertise both paths : BGP

[gauravprakash]

Hi,

I want to learn two routes to same destination from two different BGP client routers ( say A & B) on Route Reflector (RR) and force RR to advetise both BGP routes to other clients ( say X ..)..

Plz explain ( separetly) with respect to

1. normal BGP RR

2. VPNV4 RR ( in case of MPLS with PE routers A & B)

Thx

G

[Harold Ritter]

Gaurav,

1- This is currently not possible with the IOS. The RR will select only the best path an advertise it. The following draft that allows one to change this behavior and to advertise more than one path for a given prefix.

http://www.ietf.org/internet-drafts/draft-walton-bgp-add-paths-05.txt

2- This is currently possible if you configure different route distinguishers (RD) for the given VPN on the advertising PEs. The RR will consider the VPNv4 prefixes as different since the RD is different and therefore will advertise both.

Hope this helps,

[gauravprakash]

Thx..:)

can u plz send me some links which has sample config/design involving VPNv4 RR using different RD..as in Point# 2.

Thx again,

G

[Harold Ritter]

Gaurav,

Nothing fancy. It would go something like this:

PE1:

ip vrf red

rd 192.168.1.1:1

route-target both 1:1

PE2:

ip vrf red

rd 192.168.1.2:1

route-target both 1:1

Here are some good documents describing load-balancing in general in an MPLS VPN context.

Load Balancing in MPLS VPN Environments:

http://www.cisco.com/application/pdf/en/us/guest/netsol/ns172/c654/cdccont_0900aecd802e18af.pdf

Load Sharing MPLS VPN Traffic

http://www.cisco.com/en/US/products/ps6350/products_configuration_guide_chapter09186a0080442572.html

Hope this helps,