Using Mapped IP (MIP) and Subnet IP (SNIP) Address on a NetScaler Appliance

This article contains information about using Mapped and Subnet IP addresses on a NetScaler appliance.

Mapped IP (MIP) Address

You use MIP addresses to connect to the backend servers and Reverse Network Address Translation (NAT). The MIP address is one of the NetScaler owned IP addresses.

Starting with NetScaler software release 9.3, you need not configure a MIP on the appliance. However, if the Subnet IP (SNIP) address is not routable to the backend server, then you must configure a routable MIP to communicate with the backend server.

Subnet IP Address

This is an IP address that enables you to access a NetScaler appliance from an external host that exists on another subnet. When you add an SNIP address, the appliance adds an entry in the routing table. You need to add only one such entry to the routing table for each subnet. The route entry in the routing table corresponds to the first IP address added to the subnet. You can specify the SNIP in the NetScaler appliance whenever you want to enable it.

The SNIP enables the NetScaler appliance to connect to the subnet, which is different than that of the MIP and NSIP addresses, similar to local network of the appliance. This functionality is very useful in the topology where backend servers are connected directly to the NetScaler appliance through an L2 switch and are in different subnets than that of MIP and NSIP addressed servers.

The following diagram shows the use of the MIP and SNIP addresses in a network NetScaler appliance that connects to the backend servers across the subnets:

In the setup depicted in the preceding diagram, if the NetScaler appliance and the backend servers are in the 10.1.1.0/24 subnet, then the appliance uses the MIP address to communicate to the servers. However, if the setup has backend servers on additional subnets, such as 10.2.2.0/24, and there is no router between the NetScaler appliance and the subnet, then you can configure a SNIP address that has a range of 10.2.2.x/24, such as 10.2.2.9 in this case, to communicate to the additional subnet.

You can enable the NetScaler appliance to use MIP to communicate the additional subnet. However, if the setup has a firewall application between the appliance and the server, then the firewall might prevent the traffic other than 10.2.2.0/24. In such scenarios, you need a SNIP address to communicate to the servers.

Note: You must enable the Use Subnet IP (USNIP) mode on the NetScaler appliance to use SNIP address on the appliance.

Enabling the USNIP Mode

To enable the USNIP mode from the Configuration utility, complete the following procedure:

1. In the Navigation pane, expand the System node.

2. Click Settings.

3. Click the modes and select the Use Subnet IP option, as shown in the following screen shot:

   

4. Click OK.

To enable USNIP mode from the command line interface of the appliance, run the following command:
enable ns mode usnip