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ar_djp
Cisco Employee

N9K BGP multiple route advertisement and condition

Hi Experts.

 

I understand the conditional route advertisement feature using advertise-map.

Is there a way to make multiple route advertisement/conditions?

example:

advertise IP1 if IP100 exists

advertise IP2 if IP101 exists

advertise IP3 if IP102 exists

 

Thanks in advance.

2 REPLIES 2
sbhadrav@cisco.com
Contributor

You can configure BGP conditional advertisement to limit the routes that BGP propagates. You define
the following two route maps:
• Advertise map—Specifies the conditions that the route must match before BGP considers the
conditional advertisement. This route map can contain any appropriate match statements.
• Exist map or nonexist map—Defines the prefix that must exist in the BGP table before BGP
propagates a route that matches the advertise map. The nonexist map defines the prefix that must not
exist in the BGP table before BGP propagates a route that matches the advertise map. BGP processes
only the permit statements in the prefix list match statements in these route maps.
If the route does not pass the condition, BGP withdraws the route if it exists in the BGP table.
1. configure terminal
2. router bgp as-number
3. neighbor ip-address
4. remote-as as-number
5. address-family {ipv4 | ipv6} {unicast | multicast}
6. advertise-map adv-map {exist-map exist-rmap | non-exist-map nonexist-rmap}
7. (Optional) show bgp {ipv4 | ipv6} {unicast | multicast} neighbors
8. (Optional) copy running-config startup-config

j.a.m.e.s
Participant

The short answer is "not on the N9k" (have only tested in v7.x). I made a similar post about this here:
https://community.cisco.com/t5/switching/nx-os-bgp-multiple-advertise-maps/td-p/3215300

Had I known about this limitation, I would not have purchased this switch. You may be able to find another way to do what you need, such as using communities to mark your BGP routes and only advertising when the prefix has a certain community.