MP-BGP extended community

Answered Question
Oct 2nd, 2009

Hi,

I have MPLS L3 VPN with EIGRP as PE-CE routing protocol. Also I have backdoor link, that needs to be preferred.

So, I am using route map that sets bgp pre-bestpath cost community to some value.

The question is, how can I distinguish between EIGRP internal and external routes in route map to my BGP peers to set appropriate cost community?

For example:

Internal routes - cost community 128 3000000

External routes - cost community 129 3000000

I have this problem too.
0 votes
Correct Answer by Giuseppe Larosa about 7 years 2 months ago

Hello Branimir,

through the backdoor link internal EIGRP routes coming from other sites can arrive at CE routers.

I think one possible approach here is to use prefix-list or access-lists to define what IP prefixes are really located in this site.

All other prefixes that eventually are received on EIGRP from CE routers should be considered as "external" to site and less preferred / advertised in a different way.

Hope to help

Giuseppe

Correct Answer by Peter Paluch about 7 years 2 months ago

Hello,

The match route-type external and match route-type internal directives in a route map can be used to test whether a route is internal or external. However, note that this route map should be applied when redistributing your EIGRP routes into the BGP. After a route is redistributed into BGP, this command refers to the ORIGIN attribute of the redistributed route and not to the type of the original EIGRP route anymore.

Best regards,

Peter

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Correct Answer
Peter Paluch Fri, 10/02/2009 - 01:37

Hello,

The match route-type external and match route-type internal directives in a route map can be used to test whether a route is internal or external. However, note that this route map should be applied when redistributing your EIGRP routes into the BGP. After a route is redistributed into BGP, this command refers to the ORIGIN attribute of the redistributed route and not to the type of the original EIGRP route anymore.

Best regards,

Peter

Correct Answer
Giuseppe Larosa Fri, 10/02/2009 - 01:57

Hello Branimir,

through the backdoor link internal EIGRP routes coming from other sites can arrive at CE routers.

I think one possible approach here is to use prefix-list or access-lists to define what IP prefixes are really located in this site.

All other prefixes that eventually are received on EIGRP from CE routers should be considered as "external" to site and less preferred / advertised in a different way.

Hope to help

Giuseppe

Branimir Turk Sun, 10/04/2009 - 22:54

Hi paluchpeter and giuslar,

Thank you both for help and explanation.

Regards,

Branimir

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