NX-OS BGP Multiple Advertise-Maps

[j.a.m.e.s]

Dear All,

Does anyone know if nx-os supports multiple conditional advertise map statements?

advertise-map RM-ADVERTISE-OFFICE1 exist-map RM-EXIST-LOOP-OFFICE1
advertise-map RM-ADVERTISE-OFFICE2 exist-map RM-EXIST-LOOP-OFFICE2

I have successfully used this in IOS, but when I type the second advertise-map on my N9k running 7.0.3I4, the second advertise-map replaces the first.

Regards

James.

[j.a.m.e.s]

All,

I have thought of a potential workaround by using continue within a neighbor outbound route-map.

After reading IOS documentation on the subject though, I'm not clear on the logic for evaluating outbound route-maps for BGP filtering. Does the router:

1. interate through the routes scheduled to be advertised (one by one) and evaluate them individually against the route map?
2. Or does it execute the route-map logic first to build a picture of which routes could be advertised, then monitor the bgp table to see which routes to advertise?

I couldn't get a clear understanding of this from the documentation . If 2 is the modus operandi, this logic might be a workaround:

route-map RM-BGP-OUT permit 10
 descr Office1 Lo1 is in the BGP table
 match ip prefix-list PL-EXIST-LOOP-OFFICE1
 continue 200
route-map RM-BGP-OUT permit 20
 descr Office2 Lo1 is in the BGP table
 match ip prefix-list PL-EXIST-LOOP-OFFICE2
 continue 300
route-map RM-BGP-OUT permit 30
 match ip prefix-list PL-NORMAL-ADVERTISE
route-map RM-BGP-OUT deny 100
 description Block Everything Else
route-map RM-BGP-OUT permit 200
 descr Advertise Office 1
 match ip prefix-list PL-OFFICE1-ADVERTISE
route-map RM-BGP-OUT permit 300
 descr Advertise Office 2
 match ip prefix-list PL-OFFICE2-ADVERTISE
exit

[j.a.m.e.s]

All,

My earlier posts were a bit convoluted, so just to close this down the key lesson is that in NX-OS only a single advertise-map can be applied to a neighbor (when you apply a second map, the first one is removed). 

In order to emulate more than one conditional advertise statement on NX-OS I had to do a lot of work with tagging then redistributing into BGP with a particular community. This was painful, but it worked.

Regards

James.