Cabletron Systems 9032578-05 manual Dynamic NAT with Outside Interface Redundancy

Chapter 16: Network Address Translation Configuration Guide

Using Dynamic NAT with DNS

When a client from outside sends a query to the static global IP address of the DNS server, NAT will translate the global IP address to the local IP address of the DNS server. The DNS server will resolve the query and respond with a reply. The reply can include the local IP address of a host inside the local network (for example, 10.1.1.2); this local IP address will be translated by NAT into a global IP address (for example, 192.50.20.2) in a dynamic binding for the response.

Dynamic NAT with Outside Interface Redundancy

The following example configures a dynamic address binding for inside addresses 10.1.1.0/24 to outside addresses 192.50.20.0/24 on interface 192-net and to outside addresses 201.50.20.0/24 on interface 201-net:

Outbound: Translate source pool 10.1.1.0/24 to global pool 192.50.20.0/24

Translate source pool 10.1.1.0/24 to global pool 201.50.20.0/24

10.1.1.4

IP network 10.1.1.0/24

interface 192-net (192.50.20.0/24)

		Global Internet
Router
et.2.1	et.2.2
	et.2.3

10.1.1.3

10.1.1.2

interface 10-net	interface 201-net
(10.1.1.1/24)	(201.50.20.0/24)

The first step is to create the interfaces:

interface create ip 10-net address-netmask 10.1.1.1/24 port et.2.1 interface create ip 192-net address-netmask 192.50.20.0/24 port et.2.2 interface create ip 201-net address-netmask 201.50.20.0/24 port et.2.3

Next, define the interfaces to be NAT “inside” or “outside”:

nat set interface 10-net inside nat set interface 192-net outside nat set interface 201-net outside

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