NAT Pool

Alceo

Let's say i have 209.165.76.196/30 for the nat pool
ip nat pool 209.165.76.196 209.165.76.199 netmask 255.255.255.252

Using Dynamic NAT without overload how many ip can be translated at the same time, 4 or 2?
Is the rule to take away the first (subnet) and last (broadcast) address also valid in this case?

Thanks!

quickman007

Dang, I'm not sure. I'll try it out after work, although I believe you have to specify only the addresses you want to translate too, not the entire network (leaving out the network and broadcast ID). For instance 209.165.76.197 209.165.76.198, which would be the only usable addresses in the range. I know IOS checks to make sure the starting and ending addresses are in the same network based on the netmask and throws an error if they're not, but not sure what it would do in this case. I'll write back when I get a chance to test it.

Mooseboost

If I understand correctly with a dynamic nat pool it will not hand out the network or broadcast, but you can assign them through a static nat. See the below link for a similar question with a more specific answer:

https://learningnetwork.cisco.com/thread/42085

mj8mj4

Basically we need to find the how many private IP
/30 which mean the increment is 4

then ..209.165.76.196 to 209.165.76.199 (( notice that the private iPs are two only first and last unusable )
209.165.76.200



so its 2 but you still use four if you change the subnet of the private IPs


HOPE IAM RIGHT

quickman007

Forgot to reply back with my findings. Tested it out and NAT will only hand out the two usable addresses. So you can specify the whole network or just the usable addresses in the pool.

Alceo

Thanks for taking the time to check it and inform us of your finding.