Riverstone Networks WICT1-12 - Manual (Page 494)

21-8 Riverstone Networks RS Switch Router User Guide Release 8.0
Configuration Examples Network Address Translation Configuration
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 RS 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.
21.8.3 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:
Figure 21-3 Dynamic address binding with PAT
1. The first step is to create the interfaces:
2. Next, define the interfaces to be NAT “inside” or “outside”:
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
nat set interface 10-net inside
nat set interface 192-net outside
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