NAT & RAM Utilization

[RS19]

I have Cisco 2921 router. I am planning to implement NAT for users to connect to Internet.

Following are my queries.

1. Is there any way to check how much is the RAM utilized for the NAT ?

2. I understand that the max no of NAT Translations supported by Cisco ISO router depends on the RAM in the router.

           - But in router there are 2 types of memory for RAM. Processor Pool & I/O Pool.

           - Which memory is used by NAT ?

[luis_cordova]

Hi @RS19 ,

Check what this link indicates:

https://www.cisco.com/c/en/us/support/docs/ip/network-address-translation-nat/26704-nat-faq-00.html

Q. How many concurrent NAT sessions are supported in Cisco IOS NAT?

A. The NAT session limit is bounded by the amount of available DRAM in the router. Each NAT translation consumes about 312 bytes in DRAM. As a result, 10,000 translations (more than would generally be handled on a single router) consume about 3 MB. Therefore, typical routing hardware has more than enough memory to support thousands of NAT translations.

Regards

[RS19]

Thanks.

I got the below from show version.

Cisco CISCO2921/K9 (revision 1.0) with 479232K/45056K bytes of memory.

From the above which memory will be used for NAT memory consumption.

479232K OR 45056K : For NAT RAM consumption

[luis_cordova]

Hi @RS19 ,

The total size of your DRAM is the sum of those two values ​​(512MB)

The second number is a fraction of the DRAM that the router separates for Packet Memory.

You can review this discussion as a reference:

https://learningnetwork.cisco.com/thread/86550

Regards

[RS19]

Hi Thanks.

So I need to consider 512 MB of RAM ?

[luis_cordova]

Hi @RS19 ,

That's right.

Regards

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