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DC Migration Design Issue

Hi Guys

We have recently won a piece of business where we will be migrating a DC and DR site from the UK to Ireland. We were meant to be only co-locating the kit in our DC's and the company would design/implement and own all other elements of the project, including how to migrate the DC's while still keeping access to all services for their clients. Not sure how they propose to do this from an application point of view, as we are not providing new servers but there could be some load balancing in place between clustered applications, so as I move one to Ireland, the remaining device in UK is accessible, and when the device in Ireland is up and reachable, we then migrate the last box from the UK.

Now the company has stated they don't think they have the skills to perform this and so I have been assigned to it as lead engineer. I'm a CCNP, working towards CCIE Lab and have several Juniper certs also. I've been working as an engineer for 7 years now but I mainly work on PCI DSS installs and so my bread and butter in the past has been Cisco ASA's, FWSM's, and Juniper ISG's and SRXs. I can't remember when I last logged on to a router :-).

Anyway I'm hoping to get some ideas from you guys on how to make this work.

Essentially this is what I know so far:


Client currently has MPLS supplied by several providers in the UK, utilising carrier-to-carrier MPLS.

They have several client locations all across UK that connect to services in their DC

They also have a DR site in the UK that will be migrating to Ireland


Layer 3 MPLS will be commissioned between the UK and Ireland(Diverse links between locations)

ISR 2900's will be used as Edge devices between UK and Ireland

My DC here will have 6509's at dist layer.

QOS between UK and Ireland, and also Ireland DC and Ireland DR. I heard they want their date to traverse pri wan and voice to traverse sec wan link.

The client has insisted that all services remain available to their partners during the migration. They currently utilise a large broadcast domain in their UK DC where a lot of their servers reside, and everything has been piled into vlan 1. I think it's a /23 but not completely sure yet. However, I will obviously correct this in the new DC. The layer 3 MPLS link listed above will be the Production link between the clients sites that will remain in the UK and also allow their partners to connect to the new DC in Ireland. I need to find some way to extend vlan1 across the newly commissioned layer 3 MPLS so as to allow for the staggered migration of their servers, I am looking at the following:

1) Utilising L2TP across the MPLS

2) NAT the migrated servers so they are still reachable from their old address to the UK client and partners(assuming no access required during migration)

I have to perform a Proof of Concept on the migration method before the client will allow it to commence so will be going into lab on Monday morning to try out the L2TP, though they only tunnels I have ever worked on are IPSEC VPNs, so this will be a learning curve for me. I've already read about path MTU issues that may be experienced and I'm sure there will be others.

Does anybody have :

any experience on similar projects

better solution for migration

Know if MPLS provider can extend vlan1 across the L3 MPLS

reading material


Thanks in advance for any and all help, ideas etc.