Advertisement of OSPF tagged routes via BGP

[a.maldonado]

I have 2 routers in 2 different AS. R1 is learning routes from the ospf 1 process. Some of these routes are tagged as 604 in OSPF. So, what I want to do it’s to advertise these tagged routes to R2 via BGP.

I thought it would be just as simple as to create a route map with the match tag 604 statement in one of its entries and then append this route map to the neighbour statement in the BGP process. However, I just discover, the match tag command is not supported in BGP (at least not in VIRL) because when I apply the route map to the neighbour statement in R1 I get the following message and notice that I am still receiving the whole of the ospf routing table from R1 when I check in R2 (192.168.125.34).

% "TAGGED" used as BGP outbound route-map, tag match not supported

% not supported match will behave as route-map with no match

Can someone suggest a way to advertise the ospf tagged routes to the neighbour R2 via BGP? I will also need to advertise a few more routes which are learnt from other BGP neighbours and the same OSPF process, but they are not tagged. These other routes are not many and can advertise them to the neighbour using a prefix-list or ACL.

R1 BGP process

router bgp 65321

 bgp router-id 192.168.1.1

 bgp log-neighbor-changes

 timers bgp 10 30

 neighbor 192.168.125.34 remote-as 65322

 neighbor 192.168.126.81  remote-as 65323

 !

 address-family ipv4

  redistribute connected

  redistribute static

  redistribute ospf 1 match external 1 route-map RTM-4_REDISTRIBUTE_OSPF-1

  neighbor 192.168.125.34 activate

  neighbor 192.168.125.34 soft-reconfiguration inbound

  neighbor 192.168.126.81  activate

  neighbor 192.168.126.81  soft-reconfiguration inbound

  neighbor 192.168.126.81  route-map ROUTES_IN_19216812681 in

  neighbor 192.168.126.81  route-map ROUTES_OUT_19216812681 out

  default-information originate

 exit-address-family

This route map, has various entries, one of which has the match tag 604. However, it also has other entries matc hing other tags and ACLs taht I do not want to send to the neighbour.

route-map RTM-4_REDISTRIBUTE_OSPF-1

Thank you in advance for your time.

[paul driver]

All 
How can an originated prefix from an igp be redistributed with tag into bgp and be understood by bgp?

What mean is when does an igp tag prefix become an bgp prefix with an attribute based in a igp tag? 

[MHM Cisco World]

BGP use attributes and there is no attributes for tag, this is why I use community-list 

use MAPPING

tag = community-list one site, this map is happened at BGP "this BGP is outbound"
community-list = tag other site this map is happened at OSPF

[JEROME BOSC]

Hi, I am facing the same problem with my setup. Have you find a solution ?

[Harold Ritter]

Hi @JEROME BOSC ,

You could set a specific community for a given tag while redistributing the IGP prefixes into BGP and carry that value through BGP.

Regards,

[MHM Cisco World]

See my comment above.