Dynamic NAT Disadvantages and Advantages

Dynamic NAT has these disadvantages:

• If the mapped pool has fewer addresses than the real group, you could run out of addresses if the amount of traffic is more than expected.

  Use PAT or a PAT fall-back method if this event occurs often because PAT provides over 64,000 translations using ports of a single address.

• You have to use a large number of routable addresses in the mapped pool, and routable addresses may not be available in large quantities.

The advantage of dynamic NAT is that some protocols cannot use PAT. PAT does not work with the following:

• IP protocols that do not have a port to overload, such as GRE version 0.

• Some multimedia applications that have a data stream on one port, the control path on another port, and are not open standard.