Same IP address on two Networks connected by MPLS ?

[anothervr6kid]

Good morning,

I'm running into an issue and can't find a clear answer. 

I have two sites that are connected via MPLS.  OSPF is advertising the routes on the MPLS.  I am trying to move servers from site A to site B.  I want to keep the same IP on the servers once I move them over.  I can not re-IP them as they are production servers.  How can I accomplish this?

I am running a Cisco 3750 as my core on site A and a Cisco 4500 as my core on site B. 

I tried creating a VLAN on site B with the same IP subnet, but it killed my connection to site A once I did a no shut on them.

Any way to do this?

Thanks

Stephan 

[zakfleming1]

Got a few ideas none are ideal and I haven't used any of these.

You may be able to setup your WAN link as a trunk, have ports in the same vlan on each side so you have the 1 broadcast domain spanning across your WAN.

Maybe for the subnet concerned you could remove it from OSPF and have a static route for each server & manually tweak the static route when you move the server.

[anothervr6kid]

I don't think the WAN idea will work since the network is advertised over the MPLS.  Also, I don't want to saturate the WAN connection.  It is already being highly utilized on site A. 

I can't remove it from OSPF.  There are a lot of servers on site A and I only need to move a couple right away and the rest in the future.  Also, the MPLS is managed and it takes a couple days to make any changes.

[zakfleming1]

You might have issues doing that second option anyway.

Im out of ideas then. Im only CCNA, one of the big boys or girls might have an idea.

[Joseph W. Doherty]

Disclaimer

The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.

Liability Disclaimer

In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.

Posting

If you want to move hosts, and not re-IP them, and have some in two physical locations, on the same subnet, you'll need to interconnect the same locations such that the subnet spans both locations.

If you do this, traffic flows to/from your servers might be suboptimal, as they might transit your WAN even when intercommunicating hosts are at the same site.  However, if this is only needed for migration, temporary suboptimal perforamance might be acceptable.

[anothervr6kid]

I have access and can move data between both sites. 

How do I get the subsets to span across the MPLS?  

[Joseph W. Doherty]

Disclaimer

The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.

Liability Disclaimer

In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.

Posting

You define a pseudo-wire connection across MPLS.