bgp default route-target filter

[ariela]

Hi folks,

how that command works, and why it don't need to be configured on an ASBR that is functioning as RR?

Thank you very much for your support

Regards

Andrea

[cpubob]

By default, a cisco router will filter out prefixes that contain a route-target that is not use locally on that router.

This check is disabled when you configure a route-reflector-client, since the client may need one of those routes.

On an ASBR that IS already a RR, you don't need to mess with this command because the rt filter check is already turned off.

However, if your ASBR is not a RR ( or doesn't have a particular VPN configured locally) and you need to advertise VPN prefixes to another AS, then you need to turn this check off or the ASBR will filter out the prefixes when they are received from its internal peers, so it will not have them to advertise to another else. In this case, you would do a "no bgp default route-target filter" on the ASBR so the routes are accepted even though they will not be used locally.

HTH

-Rob

[ariela]

Hi Rob,

thanks for your answer. I appreciated it.

My question was: why this sort of check is disabled on RR? And is it disable only on RR with clients with VRFs configured that need these rt?

Thanks again for your support

Regards

Andrea

[Laurent Aubert · Accepted solution]

Hi Andrea,

This check is disabled by default on a VPNv4 RR because by definition it has to re-transmit to his clients any updates received from a MP-eBGP peer or another client.

If it was not the case, you have two choices:

- manually disable the check with the no bgp route-target filter all command

- Create a VRF for each VPN and manually import the routes

HTH

Laurent.

[ariela]

Thanks for all guys!

Andrea

[inboxsudhir]

Thanks .. its help me.

Sudhir