This article describes how to configure Static CGNAT on NetScaler.

Use Case

George wants to host a service on the internal network of his firm which lies behind a CGNAT hosted in Telco environment. His need is that if a particular user tries to connect to his service, the internet must allow user to do so by always routing user to the same IP address and same port.

Quick recap of CGNAT Static NA

Large-scale network address translation (LSN) also known as carrier-grade NAT (CGNAT) is a technology that several telecom companies and internet service providers are implementing to deal with the exhaustion of IPV4 addresses issue and extend the lifespan of IPv4 addresses until the world slowly moves to IPv6 addresses. LSN allows single IPV4 address to be shared by multiple private network subscribers thus allowing large number of users to connect to internet using limited IPV4 addresses.

But in some cases, there may arise a need to be able to create the mapping manually. NetScaler supports static mapping capability. A customer can opt to create a static mapping between a subscriber IP/port and a NAT IP/port. This configuration ensures that traffic from a specific subscriber IP address and port always gets the same NAT IP address and port. This mapping enables Internet hosts to reach a particular internal service.

Instructions

Configuration Steps for configuring Static CGNAT on NetScaler

You can check your static mapping using the command
show static

On NS GUI
Go to System >> Large Scale NAT >> Static and create a static mapping