NAT - translate address not directly connected to edge device

When deploying a Network Address Translation (NAT) setup, it is possible to translate addresses that are in a subnet that is not directly connected to the edge device performing the NATting.

This setup is common in complex network topologies where you might have multiple subnets and routers on the internal network. Here's how you can achieve this:

  1. Routing Configuration: The edge router needs to have a route to the non-directly connected subnet. This can be done through static routing or dynamic routing protocols. The router needs to know how to reach the non-directly connected subnet before it can translate its addresses.
  2. NAT Configuration: On the edge router, you will configure NAT rules to translate the private IP addresses from the non-directly connected subnet to a public IP address. This configuration is similar to setting up NAT for directly connected subnets, but you'll specify the non-directly connected subnet in your NAT rules.
  3. Ensure Return Traffic: Make sure that the return traffic from the internet knows how to get back to the non-directly connected subnet. This usually involves configuring appropriate routes on the edge router and possibly other routers in your network.
  4. Access Control Lists (ACLs): If there are ACLs in place, ensure they allow the necessary traffic from the non-directly connected subnet to pass through the edge router and vice versa.

While the subnet is not directly connected, as long as the edge router has a route to it and the NAT rules are configured correctly, it can translate the addresses from that subnet. Remember that proper routing and ACL configurations are crucial to make this work.