From the GUI you can hover the mouse pointer over a CGN resource allocation IP pool name to display information about the IP pool including its name and CGN mode as well as the settings of the IP pool including the external IP address and port ranges, whether ARP reply is enabled, the block size, and the number of blocks available for each IP address.
The display also shows real time data calculated for the IP pool including the number of external IP addresses currently in use, the number of client sessions currently using the IP pool, as well as a calculation of the percentage of the TCP and UDP blocks available.
The TCP and UDP blocks available is calculated as a percentage of the total number of blocks available. The following explains how the total number of blocks available is determined.
The Blocks per IP is the number of ports in the Port Range divided by the Block Size. In this example:
(65530 - 5117) / 128 = 471
The 471 blocks per IP address are distributed evenly among the available NP7 processors. For a FortiGate-4200F with four NP7 processors, each NP7 processor would have
474 / 4 = 117.75, rounded down to
117 blocks per IP address.
The total number of blocks available = blocks per IP address x number of IP addresses x number of NP7 processors. In this example:
117 x 2 x 4 = 936