Exchange 2013 Migration in a complicated network environment

Hello everyone,

I am conducting an Exchange migration from 2007 to 2013. The client have 4 geographical site and each of those site have an Exchange CAS server on it. The sites have also DCs on each of them.

There's two types of connection between sites one is MPLS that's 50MBPs and the other is p2p that's 2mbps. Client wants to have only 2 Exchange 2013 Server with all the roles collocated on them and DAG between them.

I already have installed and configured DAG on the servers. One server is located in the Central data center and the other is located on a second geographical site that also have a disaster recovery data center.

Client wants to configure the MAPI network on Exchange 2013 to use the P2P 2mbps connection and use the MPLS 50mbps connection for the replication NIC.

The problem is that both networks MPLS and P2P have the same IP subnet, same gateway e.g. ( but a range of those IPs are configured on the router to use the MPLS connectivity.

I have tried to add static route to the replication network to use the gateway but when trying to add a copy of a centralized database to the DAG. the DAG copies the connection over the P2P line.

Is it possible to configure this with the same subnet or do I need to have the mpls connection on a totally different network and subnet?

I would appreciate all your suggestions and I  am very sorry for my terrible explanation because I am my self confused about their network topology.

I will prepare a visio diagram of the network, IPs and everything to clear everything out.
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Mohammed HamadaSenior IT ConsultantAsked:
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Simon Butler (Sembee)ConsultantCommented:
IP is just IP, therefore all you would need to do is setup new IP subnets and configure the routers accordingly, That could be via a VLAN or something like that. Most routers can cope with additional subnets via VLANs. That will allow you to separate the traffic.

Exchange requires different IP subnets to allow the traffic to be separated, but the current design doesn't allow that. There isn't anything you can do to change the behaviour of Exchange, so the network design needs to be changed to allow a second subnet to go across.

Otherwise route everything over the primary, faster connection (which is what I would do).

Mohammed HamadaSenior IT ConsultantAuthor Commented:
It's the client's requirements to separate the traffic this way although I am not a network guy but I will have to ask them to create a separate subnet for the replication.

I will keep you updates.

Thanks a lot
Mohammed HamadaSenior IT ConsultantAuthor Commented:
I have removed the DAG members and removed the DAG. now waiting for the client to get a new Subnet from the ISP company in order for it to be configured also on the MPLS network between the two sites.

I'm wondering in case I got the new subnet .. let's assume that it's how I am going to configure my replication NICs?

If I configured them on both sites with only IP and subnet Mask without a gateway they won't ping or connect to each other. so in this case i'll have to write a static route to add the gateway in the routing table ? or there's another configuration that I am missing?

Simon Butler (Sembee)ConsultantCommented:
A manual static route is what you need to do. You don't set a default gateway.


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Mohammed HamadaSenior IT ConsultantAuthor Commented:
Thanks Simon.. that worked
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