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Configuring RNAT with LLB

September 21, 2020
Contributed by:  S C

You can configure an LLB setup for reverse network address translation (RNAT) for outbound traffic. This ensures that the return network traffic for a specific flow is routed through the same path. First configure basic LLB, as described in “Configuring a Basic LLB Setup”, and then configure RNAT. You must then enable use subnet IP (USNIP) mode.

In the following diagram, the NetScaler appliance uses LLB to route outbound traffic to different links. During the RNAT operation, the NetScaler appliance replaces the source IP addresses of the outbound traffic with the public NAT IP address (198.141.23.1) to route the traffic through ISP-1. Similarly, the NetScaler appliance replaces the source IP addresses with 198.140.23.1 to route the traffic through ISP-2.

RNAT with LLB

To add SNIPs for ISP routers by using the command line interface

At the command prompt, type:

add NS IP <subnet of first ISP in the IP router> <subnet mask> -type SNIP

add NS IP <subnet of second ISP in the IP router> <subnet mask> -type SNIP

Example:

add ns ip 10.140.23.1 255.255.255.0 -type snip

add ns ip 10.141.23.1 255.255.255.0 -type snip

To configure RNAT by using the command line interface

At the command prompt, type:

set rnat <network> <netmask>

show rnat

Example:

set rnat 10.102.29.0 255.255.255.0 -natIP 10.140.23.1
set rnat 10.102.29.0 255.255.255.0 -natIP 10.141.23.1
show rnat
    1) Network: 10.102.29.0      Netmask: 255.255.255.0
     NatIP: 10.140.23.1
     2) Network: 10.102.29.0      Netmask: 255.255.255.0
     NatIP: 10.141.23.1

To configure RNAT by using the configuration utility

  1. Navigate to System > Network > NATs.
  2. On the RNAT tab, click Configure RNAT.
  3. Specify the network on which to perform RNAT.

Note

You can also configure RNAT by using Access Control Lists (ACLs). Refer Configuring RNAT for details.

To enable Use Subnet IP mode by using the command line interface

At the command prompt, type:

enable ns mode USNIP

show ns mode

Example:

enable ns mode USNIP

show ns mode
        Mode                           Acronym              Status
        -------                        -------              ------
 1)     Fast Ramp                      FR                   ON
 2)     ….
 8)     Use Subnet IP                  USNIP                ON
 9)     …

To enable Use Subnet IP mode by using the configuration utility

  1. Navigate to System > Settings and, under Modes and Features, click Configure Modes.
  2. In the Configure Modes dialog box, select Use Subnet IP, and then click OK.

Configuring RNAT with LLB

September 21, 2020
Contributed by:  S C
September 21, 2020
Contributed by:  S C

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