Adding A Replication Network To An Exchange 2010 DAG…
As most of the exchange admins plan the deployment of new versions of Exchange, there might be a case where you start the deployment of an Exchange 2010 DAG with a single NIC (for both MAPI and replication, which is supported by Microsoft as well), but later on, you think of configuring a dedicated replication…
As most of the exchange admins plan the deployment of new versions of Exchange, there might be a case where you start the deployment of an Exchange 2010 DAG with a single NIC (for both MAPI and replication, which is supported by Microsoft as well), but later on, you think of configuring a dedicated replication network for the DAG. The process is pretty straight forward – you add additional NIC to your DAG members, configure the correct IP & routing and that’s it. Exchange should start using the dedicated replication network for log shipping and seeding.
The trouble is that though you have taken all the right steps, sometimes Exchange won’t recognize the new replication network and hence won’t use it. So, how do you get around the problem? Let me explain based on my lab.
I have a two node DAG up and running with a single NIC.
I have one DAG network, which is named as MAPI. The replication traffic goes through the same network as well at the moment.
Now, I add a new NIC for replication network and configure the IP & routing.
But, Exchange still doesn’t see it and doesn’t create a new DAG network as expected. The reason is that Exchange only scans for the networks on DAG members when a server is added to the DAG. After that, the networks are scanned only if you tell Exchange to do it. All we need is a one-liner in Shell to force Exchange to recognize the new NIC & thereby creating a new DAG network. Run the following command in Exchange Shell.
Set-DatabaseAvailabilityGroup “DAG Name” –DiscoverNetworks
As expected, Exchange shows the new DAG network in the console.
We’re looking to configure an Exchange 2013 environment with a DAG. Our question is what are we losing out with when going with a single NIC for both MAPI and Replication? Is it that big of a game changer? We’ll be using 3 servers in the DAG and all will be located in the same physical network servicing roughly 1800 mailboxes. I just want to make sure we have it right during the initial build so we don’t have to make a change once it is in production.
Having two NICs was more of in the Exchange 2010 world and only makes sense if you have two different routes, one for production traffic and another separate network for replication. If they are going to go through the same pipe, just stick with one NIC.
In Exchange 2013 and later, it is better to have just one NIC.
Great article. I have a second NIC that I am going to use solely for replication and this article is a great find. My question is now that you have two NIC’s connected is the original NIC still replicating DAG information? How do you set the MAPI NIC form the DAG Network so that it is only being used for MAPI traffic?
Select the properties of the network in EMC and check the options you want.
can we use two NIC for DAG, 1 is for Mapi and 2 is for private replication at the time of DAG creation or we have to complete the DAG on single NIC first and then Add additional NIC for replication as mentioned above.
Plz help me out.
You can have two NICs when you configure the DAG or add the second one later and re-configure the DAG later.
Both are fine.
You don’t have to have a separate NIC for replication if you don’t have a different pipe or VLAN. Single NIC DAG is fully supported.
Can you have DAG without replication NICs?
Yes, you can Brent. You can run a DAG with a single NIC on the server.