Cabletron Systems SmartSwitch manual Dynamic NAT with IP Overload PAT Configuration

Chapter 14: Network Address Translation Configuration Guide

Dynamic bindings are removed when the flow count for that binding goes to zero or the timeout has been reached. The free globals are used again for the next packet.

A typical problem is that if there are more local IP addresses as compared to global IP addresses in the pools, then packets will be dropped if all the globals are used. A solution to this problem is to use PAT with NAT dynamic. This is only possible with TCP or UDP protocols.

Dynamic NAT with IP Overload (PAT) Configuration

The following example configures a dynamic address binding for inside addresses 10.1.1.0/24 to outside address 192.50.20.0/24:

Outbound: Translate source pool 10.1.1.0/24 to global pool 192.50.20.1-192.50.20.3

			10.1.1.4
					Router
IP network 10.1.1.0/24
					et.2.1	et.2.2
	10.1.1.3	10.1.1.2		interface 10-net
				(10.1.1.1/24)

Global Internet

interface 192-net (192.50.20.1/24)

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 192.50.20.1/24 port et.2.2

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

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

Then, define the NAT dynamic rules by first creating the source ACL pool and then configuring the dynamic bindings:

acl lcl permit ip 10.1.1.0/24

nat create dynamic local-acl-pool lcl global-pool 192.50.20.1-192.50.20.3

SmartSwitch Router User Reference Manual 229