Dynamic NAT Allocation

[m.haran]

I have a pool of addresses that is approx 2000 IP addresses in size. These addresses are dynamically assigned from the NAT router for incoming traffic.

The problem we find is that the assignment of the network and broadcast address in from these pools sometimes cause problems with connections. This leads to manual clear down of the translations and waiting for a valid ip address to be assigned.

My question is whether there is a global command that can be enabled that prevents allocating broadcast and network addresses or will I have to create a number of separate pools or acl's to deny those IP addresses being allocated.

[gfullage]

No, there's no single command that will stop, if your pool contains them then they'll get allocated (broadcast/subnet addresses are valid addresses with the right subnet mask).

You're better off doing something like the following:

ip nat pool natpool prefix-length 24

  address 10.1.1.1 10.1.1.254

  address 10.1.2.1 10.1.2.254

  address 10.1.3.1 10.1.3.254

andn then use that NAT pool in your commands.