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Cisco 7301 maximum supported NAT table entries

senpai
Level 1
Level 1

I am trying to figure out what is the maximum supported NAT table entries for this EOL Cisco 7301 router. Yes, I know its an old hardware but it still works. The Datasheet shows 16k for 12.2(13)B. I believe this count refers to the BB subscribers supported but not for NAT. Can anyone tell me how to figure out the max supported NAT entries on this router (NAT Overload)? I am running version Cisco IOS 15.2(4)S6 (ADVENTERPRISEK9) 

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Hello,

 

there used to be a global configuration command 'ip nat translation max-entries' which should tell you what the upper limit is.

That said, it is difficult to give a hard limit, as that depends on what else is configured on your device, and how much memory you have. A single NAT translation uses about 312 bytes in DRAM. The 7301 supports up to 1Gigabit of DRAM, so in theory, if you have that much DRAM installed, it would support 400,000 NAT entries...

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6 Replies 6

Hello,

 

there used to be a global configuration command 'ip nat translation max-entries' which should tell you what the upper limit is.

That said, it is difficult to give a hard limit, as that depends on what else is configured on your device, and how much memory you have. A single NAT translation uses about 312 bytes in DRAM. The 7301 supports up to 1Gigabit of DRAM, so in theory, if you have that much DRAM installed, it would support 400,000 NAT entries...

Thanks for the tip with max-entries. Since these entries, only would show the capability from the IOS version that's in use rather than the hardware, as you have suggested it would depend on the memory in use. Its currently got 1G of memory.

If you have 1GB Ram what @Georg Pauwen was said correct. again i have not seen that many translation i have not seen  in real time. until it is Service provider environment.

BB

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Thanks, @balaji.bandi It is used for a test environment at SP Level :) So expecting quite a fair amount of translation to happen.

Something else that might also "help", if you find you're running out of NAT entries, if there's a command to adjust timers for how long a NAT entry is maintained, decreasing that may effectively increase your NAT number of entries as stale entries would become available sooner. Of course, the downside of this is you might also drop active entries that are still active, just "slow".

interesting. depending on how the table grows, might as well look into adjusting these timers, if possible. thanks for the input @Joseph W. Doherty
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