Number of nat entry in a 2651

[pthepault]

I'm trying to get a method to calculate the number of entries in the nat table of a 2651XM with 32M of ram.

[ankurbhasin]

HI Friend,

Theoretically, there is no limit on the number of mappings that the NAT table can hold.

Practically, memory and CPU or the boundaries of the available addresses or ports place a limit on the number of entries.

Each NAT mapping uses approximately 160 bytes of memory.

In the rare case where the entries must be limited either for performance or policy reasons, you can use the "ip nat translation max-entries" command.

As you said your router is having 32 MB of memory it can hold approx 209715 entries taking into account 1MB = 1024 KB and 1 KB=1024 B

HTH

Ankur

[mheusinger]

Hi,

just a sidenote on the previous post. Most of your memory will be used for IOS, I/O mem and other things. And there should be some memory left for normal operations.

So you can check free memory under normal operation (show processes memory) and then give a rough estimation with the 160 Bytes per entry.

With only 32 MB memory I would definately recommend to use "ip nat translation max-entries" as mentioned above.

Hope this helps

Martin