BGP Conditional Advertisement Feature

[sirlollypop]

I wish to have a conditional advertisement for some of the networks statements to a BGP neighbour while some are always advertised, assuming the route for that network is in the routing table.

This is advertising between a pair of AS on the same router. Which is a 7200 running a 12.4 code.


So there would be 2 groups of routes:


A) Always advertised assuming there is a route

B) Advertised if its condition route is met as well as the route is in the routing table of the router.


I have set up a conditional only and not the mix, which is relatively simple.

Any pointers or config examples would be great.

 

[brianinms]

Sounds like a job for a prefix-list

 

[baddos]

iBGP normally will not advertise a network if it does not have a route for it.

Depending on the condition you may need to use a route-map. Can you describe what your criteria is so we can offer suggestions?

 

[sirlollypop]

I will be using eBGP rarther than iBGP.

But an example of what I need but not real addressing is:

router bgp 2
bgp log-neighbor-changes
network 128.16.16.0 mask 255.255.255.0
network 130.130.0.0
neighbor 10.10.10.1 remote-as 1
neighbor 10.10.10.1 advertise-map ADVERTISE exist-map EXIST
<<<This will only advertise routes into AS 1 that exist in the advertise map when the condition in the exist-map is there. i.e a route.
neighbor 10.10.20.3 remote-as 3

But I also need to advertise certain other routes from AS3 to AS1 whether the exist map is matched or not.

 

[baddos]

Something like this?

http://www.cisco.com/en/US/tech/tk365/technologies_configuration_example09186a0080094309.shtml

Make sure when you do set this up though to use a private AS instead of 1 and 3. A private AS number would be in the 64512 to 65535 range.

 

[unclerico]

so what are you seeing?? can you post your config?? what should happen is all other routes not filtered by a filter-list, distribute-list, or conditional advertisement should still be advertised. the only route(s) affected by the conditional advertisement are the ones that are in your adversise-map

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