MPLS/VPN SOO

aretsu · ‎12-10-2003

Hello,

I have a question regarding SOO ext community.

Lets say that I have one customer site with 2 CEs, each CE connects to one different PE Router on the Service provider site. They are running eBGP as PE-to-CE routing protocol AND as-override is enable.

The question is, the SOO atribute that I use on the route-map MUST be the same that the RD or RT values? or I can just choose an arbitrary number that marks the SOO attribute with any value that I want?

example:

ip vrf TEST

rd 100:1

route-target import 100:1

route-target export 100:1

!

!

! *** IS THIS A MUST? ***

route-map setsoo permit 10

set extcommunity soo 100:1

!

! *** OR CAN I USE ANY NUMBER? ***

route-map setsoo permit 10

set extcommunity soo 100:501

Any comments, please let me know...

regards!

Alex

rwiesmann · ‎12-11-2003

Hi Alex

You do not have to configure it the same, means you can use any arbitrary number. the soo is just another BGP extended community attribute

I guess the goal is that routes are not advertised back to the second ce.

The soo prevents routing loops when a site is multihomed to the mpls/vpn backbone, and in addition

the site uses the AD-override feature.

So you have to set the soo on on both sites the same.

Hope that helps

Roger

aretsu · ‎12-11-2003

Does it means that I can use the same route-map setting the SOO attribute for many customers? I mean, if the ext community attribute does not need to be the same that RD or RT values, and it can be any value, I can apply this route-map for many customers at the same time?

Regards!

rwiesmann · ‎12-11-2003

Hi

Yes, basically it means that as long as you have just one redundant location per customer (MPLS/VPN) you could use the same soo for many customers.

I still would not implement it this way. Just consider a scenario in which you have to change the soo for some reason for some customer (MPLS/VPN's). I would use one route-map for each customer this way you have the flexibility to change things. You also have to be aware that if a customer has more then one location which is redundant that you can't use the same soo values.

The bgp ext communities draft specifies the route target and the route origin as ext. communities. the route origin, refered as the soo by the cisco implementation, prevents routing loops between sites, and the route target ext. community defines the import and export policies that a particular VRF uses.

Hope that gives you a hint.

Regards

Roger