Cabletron Systems 9032578-05 manual Using Dynamic NAT

Chapter 16: Network Address Translation Configuration Guide

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 192.50.20.0/24

Using Dynamic NAT

Dynamic NAT can be used when the local network (inside network) is going to initialize the connections. It creates a binding at run time when a packet is sent from a local network, as defined by the NAT dynamic local ACl pool. The network administrator does not have to worry about the way in which the bindings are created; the network administrator just sets the pools and the SSR automatically chooses a free global IP from the global pool for the local IP.

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.

226 SmartSwitch Router User Reference Manual