07-02-2012 06:10 AM - edited 03-04-2019 04:51 PM
I am on the customer side of BGP with my carrier
Looking for the best way to filter the carriers networks(our BGP interfaces and neighbors) from being redistributed from BGP to EIGRP
Thanks
07-02-2012 06:18 AM
Hi there,
route-maps and prefix lists.
HTH,
Soroush.
07-02-2012 08:33 AM
Soroush - thanks for the reply. I was hoping for a little more info. Anyone have an example or link explaining this a little more?
07-02-2012 09:26 AM
you can control what routes be redistributed into your EIGRP instance from BGP, with route-maps.
you select the routes you want or you dont want to be redistributed with prefix-lists, then using route-maps you call those prefix-lists and Allow or deny them. then you apply the route-map while configuring the redistribution.
example, if i dont want network 172.16.55.0/24 and 192.10.1.100/26 to be redistributed into my EIGRP:
ip prefix-list EIGRP permit 172.16.55.0/24
ip prefix-list EIGRP permit 192.10.1.0/26
route-map BGP_EIGRP deny 10
match ip address prefix-list EIGRP
route-map BGP_EIGRP permit 20
router eigrp 100
redistribute bgp 20 route-map BGP_EIGRP metric xxxx
Also keep in mind to setup appropriate metric for the routes comming from BGP.
useful link: http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a008009487e.shtml#ex2
if you had further questions plz ask
plz Rate if it helped,
Soroush.
07-02-2012 09:49 AM
Soroush - thanks for the explanation. A few questions. on the prefix-list its permit and it gets denied on the route map, is that correct ? Also, is route-map BGP_EIGRP permit 20 to permit all other routes ?
Thanks
07-02-2012 10:30 AM
yes, for this task you permit network perfixes (based on ur decision) and the prefix-list gets denied in the route-map, then the route-map is assigned to the redistribution process.
route-maps (like access-lists) have an implicit deny at the end. so whenever u r using route-maps to filter routes, you have to have this in mind.
however, if you want to let a few subnets to be redistributed in the EIGRP, i suggest u do the opposite, permit the ones u want and deny all other.
HTH,
plz Rate if it helped.
Soroush.
07-02-2012 10:42 AM
but in this case route-map BGP_EIGRP permit 20 allows everything else ??
07-02-2012 10:55 AM
yes it allowes everything else.
Soroush.
07-02-2012 11:41 AM
Ok - thanks for the info
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