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Routing when site has two MPLS vendor routers

We will soon be opening a new site that will have two different vendor MPLS routers to which our LAN will connect.This is Site A.

Both vendors will be advertising the new subnet(s) that we create for our new site A.

The people who will be relocated to this new site A will need to access the servers back at their old location Site B. This site B also has the same two MPLS vendors as the new site. The two MPLS vendors do not connect to the same locations except for this one location Site B.

Both sites will have a L3 switch in service.

Given that both vendors at site B will be advertising that they know about this new subnet at site A.  

How does routing work for the return route from site B to Site A?

Can I just put an ip static route on the L3 switch of site A and B pointing to which MPLS vendor is prefered for the route?

Site A is 192.168.20.0/24

Site B is 10.48.1.0/24

Site A L3 switch: ip route 10.48.1.0 255.255.255.0 192.168.20.251  (.251 is the ip address of the prefered router to Site B)

Site B L3 switch: ip route 192.168.20.0 255.255.255.0 10.48.1.1 (.1 is the ip address of the prefered router back to Site A)

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Hall of Fame Master

Routing when site has two MPLS vendor routers

John

There is a lot that we do not know about your environment. And it is likely that there are things about it that we do not know that would affect our answers about what would be best to do. But in general if you want to put a static route pointing to the preferred vendor that could work.

Having a single static route to the preferred vendor would not provide fail over in case of problems with the preferred vendor (and if it is not fail over, then what is the reason to have the second vendor?).

Also your post mentions the vendors advertising the routes that they know which suggests that there is a dynamic routing protocol running. If that is true then it would probably be better to use the dynamic routing protocol(s) than to depend on a static route.

HTH

Rick

HTH

Rick
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Participant

Routing when site has two MPLS vendor routers

Rick

Thanks for the response.

The reason there are two MPLS vendors has nothing to do with backup. (I know, hard to believe).The second vendor at site A will be gone in about year but we have to deal with what we have been given. Once all the folks are relocated to the new site A we will remove the second vendor. So for clarification we have vendor old and vendor new.

Static verses dynaminc

The old site B is in fact using rip to advertise their routes via vendor old.

This is what the vendor old has in the config:

router rip

version 2

redistribute connected

redistribute static

The L3 switch at Site B has several static routes.

I don't know what the other vendor new router config looks like at site B. At the present time vendor new is there for only one purpose and it is not for backup.

The new site A is not planning on dynamic. Site A will be configed just like all our other remote sites. And we do not use dynamic on L3 switch we just use a default route pointing to the ONE vendor router that we have.

So given this fuller explanation do you think the IP static as proposed will do it for us?

Highlighted
Hall of Fame Master

Routing when site has two MPLS vendor routers

John

You have told us that the second vendor is not there to provide redundancy and that is helpful to know. But you have not explained to us what you want the behavior to be with two vendors. And that makes it difficult to give you good advice.

If you configure the static routes as described in your original post then all traffic should flow through the preferred vendor and the other vendor will carry no traffic. Is that the desired behavior?

HTH

Rick

HTH

Rick
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Participant

Routing when site has two MPLS vendor routers

Rick

Thanks for asking for more clarification because it helps me to think this through.

No the desired behavior is listed below.

Actually I guess I would need multiple statics because only some of the people, those relocating from Site B would need to access their old servers back at site B through vendor old while everyone else would use vendor new to access the rest of the network.

So could I place two statics on the L3 switch?

One to direct people who need to get to 10.48.1.0 via vendor old and one to send people to vendor new for every other destination.

Site A L3 switch: ip route 10.48.1.0 255.255.255.0 192.168.20.251  (.251 is the ip address of vendor old to Site B)

Site A L3 switch: ip route 0.0.0.0 0.0.0.0 192.168.20.254 (.254 is the ip of the vendor new to the rest of the network)

Highlighted
Hall of Fame Master

Routing when site has two MPLS vendor routers

John

I believe that we are making progress. But I still am not sure that we really know what behavior you  want.

You certainly could configure the two static routes in your most recent post. The result would be that everyone at site A would use vendor old to access site B and that everyone would use vendor new to access everything else.

In the most recent post you say in part "only some of the people, those relocating from Site B would need to access their old servers...". This makes me wonder what about the people not relocating from site B. Would they be able to access the servers at site B? Do you want to make routing decisions based on where the traffic comes from? That would sound like it might need Policy Based Routing.

HTH

Rick

HTH

Rick
Highlighted
Participant

Routing when site has two MPLS vendor routers

Rick

I quote you below.

"You certainly could configure the two static routes in your most recent post. The result would be that everyone at site A would use vendor old to access site B and that everyone would use vendor new to access everything else."

This is the desired behavior.

The other issue you raised.

The issue is this. We are integrating part of another company into our company and until we get everything worked out (migrating their data to our site), the folks who move to new site A from any other location from this company will need to be able to access data at old site B (their main dc) thus the reason we have both vendors at both locations. This company has many other sites that do not have dual vendors and have no need to access data at site A. They do everything with site B via vendor old.

You asked if I want or need to make decisions based on where the traffic comes from. Yes, I guess.

When people from site A access data at site B and B needs a return route we want them to come back the same way they got there.

So if they came from site A via the route from my example static;

Site A L3 switch: ip route 10.48.1.0 255.255.255.0 192.168.20.251  (.251 is the ip address of vendor old to Site B)

They need to go back the same way from site B. So I need a static on site B that directs them back to 192.168.20.0 which they currently do not have because all of this happens in December.

Thanks a lot for asking all the questions. This is what makes this fourm so valable when people like you take the time to help out!