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Type B Inter-AS :How to limit number of route-target ?

chintan-shah
Level 3
Level 3

Hi,

We came across one problem in our network that we get couple of prefix from our peering partner's customer with very long ( almost more than 100) RT on our ASBR. This caused huge problem with our legacy PE router and MP-BGP session with RR went down on all our PE.

What should be solution I should look on ASBR for Type-B NNI ? Is that something we can do to limit number of RT while doing peering with our peer ?

Regards,

Chintan

3 Replies 3

Giuseppe Larosa
Hall of Fame
Hall of Fame

Hello Chintan,

the bgp rr-group can be used on a Route Reflector server to decide what  vpnv4 prefixes to reflect to clients referring to an ip extcommunity extended access-list using regular expression in address.family VPNv4 context

It is not a check on the number or RTs attached to the VPNv4 advertisement.

However, there is not , as far as I know, the equivalent of bgp max-as command that can decide the max acceptable AS path attribute length.

see

http://www.cisco.com/en/US/docs/ios/iproute_bgp/command/reference/irg_bgp1.html#wp1072398

Hope to help

Giuseppe

Hi Giuseppe,

Yes, This could be one of solution which we are applying on ASBR itself but if correct RT comes with lot more number on prefix , create an issue.

I was thinking we do re-write of RT as per below :

http://www.ciscosystemsnetwork.org/en/US/docs/ios/12_2s/feature/guide/fsrtrw4.html#wp1027173

I guess this required per customer ( i.e. customer of our Type B peering partner) and we need to know RT and then one to one re-write completely , i mean delete whatever commign and add our own RT.

Does any one have expreince on this on live enviorment ?

Regards,

Chintan

Hello Chintan,

I agree this route target rewrite feature could be the right tool for the job but as you noted a route-map clause is needed for each customer VPN and this clearly leads to a scalability problem

Hope to help

Giuseppe

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