Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. If you'd prefer to explore, try our test area to get started. And see here for current known issues.

New Member

837 periodically stops NATing


I have a modem which, as per topic, periodically stops NATing.

I have diagnosed this based on the fact I can still ping Internet addresses from the modem with no issues, and connect to the modem from any desktop, however my desktops are unable to ping those same Internet sites. I can resolve this by running:

clear ip nat translation *

This would lead you to believe there was some kind of memory exhaustion or similar basedon there being too many connections. I don't know what reasonable memory values are, but see here, taken during the problem:

internetz#show memory

Head Total(b) Used(b) Free(b) Lowest(b) Largest(b)

Processor 81920F50 21466288 10446512 11019776 10874400 10835784

I/O 2D99C00 2515968 783556 1732412 1623088 1731836

Also, my number of translations just doesn't look remotely high:

internetz#show ip nat statistics

Total active translations: 10 (0 static, 10 dynamic; 10 extended)

Outside interfaces:

Dialer0, Virtual-Access2

Inside interfaces:


Hits: 12596816 Misses: 274138

CEF Translated packets: 12691877, CEF Punted packets: 36541

Expired translations: 296197

Dynamic mappings:

-- Inside Source

[Id: 1] access-list 100 interface Dialer0 refcount 4

Queued Packets: 0

Full config is below. You can see forwards for torrents, which were initially blamed for the issue, but I've had that service shutdown for days, and confirmed all the desktops were doing almost nothing with netstat, while still managing to stop the modem passing traffic.

And of course, IOS:


I pasted the config here but it was too long, so it's attached.

I was running the "plus" version but dropped down to see if the lower RAM requirement helped.

Hall of Fame Super Gold

Re: 837 periodically stops NATing

Can you upgrade ?,eg 12.4(3j).

New Member

Re: 837 periodically stops NATing

When I received this modem, it had a 12.4 IOS on it. It would never boot, erroring out with a lack of memory. Hence I downgraded it.

I'm happy to look at an upgrade, but I was of the understanding all 12.4 releases required similar amounts of RAM.

Hall of Fame Super Gold

Re: 837 periodically stops NATing

You could try upgrading to something that doesn't require more ram, and doesn't have the bug. Unfortunately I'm unable to tell you which version that could be.