In this Tutorial we are going over the process to configure the network adapters for any given DAG member and it is a good practice to perform such configuration before creating a new DAG.
A few hints when configuring Network Adapters in a DAG member:
- Leave IPv6 alone, don’t disable just leave it there
- Be consistent with the number of network adapters among all members of the same DAG
- Be consistent with routing as well, members of the same replication network must be able to communicate
- You can use 1 adapter however it is recommended to use 2 adapters
- You can have a DAG using just one NIC however it is recommended two use at least two interfaces (you can have more if you want to)
- Round trip latency has to be less than 500ms
- Name the adapters accordingly with their purpose (Client/LAN, Replication and so forth)
- If you do have only 2 DAG members you can use a crossover cable between those 2 servers in the replication network. If you decide to scale up, then you need to use a switch to isolate traffic from 3 or more servers for the replication network
In this article series we are going to deploy the following scenario and in the picture below we can validate that there is a production network 192.168.10.0 which is Toronto site and 192.168.20.0 which is Porto Alegre site. On both sites there is also a replication network (172.16.10.0 being used in Toronto and 172.16.20.0 being used in Porto Alegre).
The first step is to rename the adapters for a name easy to identify and for this Tutorial series we are going with LAN and Replication.
Configuring the Replication Network…
In the Replication network we must make sure that Client for Microsoft Networks and File and Printer Sharing for Microsoft Networks is disabled.
Now, let’s click on Internet Protocol Version 4 (TCP/IPv4) and let’s click on Properties, and on the initial window, let’s make sure that we don’t have a gateway configured neither a DNS.
Click on Advanced… and then click on DNS tab.We must make sure that the replication IP is not being registering in our DNS. Let’s make sure that we uncheck the option Register this connetion’s addresses in DNS
Make sure to repeat the process that we just went through on all Replication networks of all future DAG members.
Replication Network routing…
If you have multiple sites like the one shown in the scenario of this article, then we need to work on the routing between the main site (Toronto) and DR site (Porto Alegre).
We know that TOREX01 has the LAN 192.168.10.21 and Replication IP is 172.16.10.21, and we know that on the second site we have POAEX01 which has 192.168.20.21 (LAN) and 172.16.20.21 (Replication).
In order to enable the replication in that specific scenario we can run the following command in Toronto site on all Exchange Servers.
route add 188.8.131.52 MASK 255.255.255.0 172.20.0.1 –p
- 184.108.40.206 destination network
- 255.255.255.0 netmask
- 172.20.0.1 local gateway to get to the destination network
- -p makes that rout persistent
For the DR we just need to run a similar command on all Exchange Servers.
route add 172.20.0.0 MASK 255.255.255.0 220.127.116.11 –p
Now we should be able to ping the replication network of each server that is going to be part of the DAG.
Managing iSCSI Networks..
If you have an iSCSI network the DAG will create a DAG Network for it and you can easily spot it running Get-DatabaseAvailabilityGroupsNetwork.
Set-DatabaseAvailabilityGroupNetwork –Identity <DAGName>\<DAGNetworkName> -ReplicationEnabled:$false -IgnoreNetwork:$true