Dynamic NAT with Overload

DPG

Scenario:

ISP IP's assigned - 200.200.200.8/29 (200.200.200.10 - 200.200.200.14 are usable since 200.200.200.9 is the ISP's router)

I would like to use dynamic NAT with overload to map my private network to multiple public IPs.

My confusion when I create the NAT pool:

ip nat pool PUBLIC 200.200.200.10 200.200.200.14 netmask 255.255.255.248

or

ip nat pool PUBLIC 200.200.200.10 200.200.200.14 prefix-length 29


Is the netmask or prefix-length dependent on the actual size of the subnet or the class?

DPG

Here is an example from Cisco. They are using the actual subnet mask.

CONFIGURATION EXAMPLES

The following sample configuration translates between inside hosts addressed from either the 192.168.1.0 or 192.168.2.0 nets to the globally-unique 171.69.233.208/28 network.

ip nat pool net-20 171.69.233.208 171.69.233.223 netmask 255.255.255.240


Now this brings up another question. Why are they including 171.69.233.208 and 171.69.233.223 in the NAT pool? They are the network address and broadcast address.

Further down the page they give another example, this time without the network and broadcast address.

Example:
ip nat pool provider1-space 171.69.232.1 171.69.232.254 prefix-length 24


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