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Prepending specific subnets

I am trying to prepend specific subnets that I am advertising. What is the best method to do this with these 3 options? Basic route-maps, route-maps with continue statements, or route-map with policy lists. What other valid options do I have?

Will this work with basic route-maps?

Route-map continue command? It is only supported on a few versions of IOS all of which I?m not currently running.

http://tinyurl.com/ybwh9a

Policy list? Kinda confusing with Cisco?s statement that ?Policy lists support only match clauses and do not support set clauses. However, policy lists can coexist, within the same route map entry, with match and set clauses that are configured separately from the policy lists.?

http://tinyurl.com/yyt2on

Any suggestions are appreciated, thanks!

-JGR

2 REPLIES

Re: Prepending specific subnets

Hi,

If you want to have a simple and clear configuration , then it would be better to go with a route-map .

As we have many features available with the route-map and your requirement is only for matching some specific subnets , it would be better to use the route-map , so that during troubleshooting time also you will not have mcuh to check.

Hope this helps

regards

vanesh k

Re: Prepending specific subnets

Route map is the best option here as it offers you lot of features.

sample config in which u advertise one subnet with prepend

router bgp 100

network 10.10.10.0 mask 255.255.255.0

network 20.20.20.0 mask 255.255.255.0

neighbor 1.1.1.1 remote-as 200

neighbor 1.1.1.1 route-map map1 out

access-list 1 permit 10.10.10.0 0.0.0.255

access-list 2 permit 20.20.20.0 0.0.0.255

route-map map1 permit 10

match ip address 2

set as-path prepend 100 100 100 100 100

route-map map1 permit 20

match ip address 1

HTH, rate if it does

Narayan

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