Routing manipulation within MPLS network

[ciscoravikiran]

Hi All, 

I have a requirement where we have one DC in Singapore (APAC) and other in London (EMEA). Currently, all remote sites connect to London via MPLS for Internet access. However, now we need to route APAC sites to use Internet from Singapore and EMEA sites to use Internet from London DC. 

I know we use Communities to tag the default route and manipulation will be done by Service Provider at MPLS end. 

Can you please confirm if changes will be required to be done on all the PE's connecting remote sites and what changes will need to be made.

Thanks in advance.

[lespejel]

hello @ciscoravikiran

changes must be applied to all PE's to keep consistency, but that's ISP responsibility, however I think you should ask for details, BGP is not able to load balance among several NRLI, so if a route reflector receives 2 routes or more, it will announce only the best one, then all PE will have only one route and they will import that based on communities as you mentioned.

If your ISP has several regions, like APAC and EMEA, it's possible those routes are exchanged with inter AS solution or something.

from your explanation the straight answer is yes,  but it's not that simple from the technical standpoint. 

[ciscoravikiran]

Thanks Iespejel for the response. 

So, if it is between APAC and EMEA then ISP will have Core router sitting between these 2 regions right. In which case, we just have to manipulate the default route metrics from these routers rather than doing on all PE routers. 

[lespejel]

That's right, Reflectors will get both and distribute only the best one for each region.