How to free up RAM?

[alesandro]

Hi I'm an absolute beginer to cisco.
We have a cisco 3640 wich is our border router to the internet and is also doing NAT. Lately its memory is filling up at a slow but constant rate and naturaly when it reaches closly to 100% it starts to realy slow down the trafic. We now have to restart it on a dayly baseis.
How can I free up memory?

 

[IllegalOperation]

Sounds like your router is getting hit with a virus. Most likely it is the Nachi. It fills your NAT table with random ICMP entries. show ip nat stat/show ip nat trans will give you an idea what is going on in there. If you notice it constantly increasing (especially with ICMP entries), then purge it out with the " clear ip nat trans * " command.

Upgrade your IOS to the latest version and scan your network for viruses....

 

[VladJ]

Apply this access-list to Ethernet :
access-list 121 deny icmp any any echo
access-list 121 deny udp any any eq netbios-dgm
access-list 121 deny udp any any eq netbios-ns
access-list 121 deny udp any any eq netbios-ss
access-list 121 deny tcp any any eq 135
access-list 121 deny udp any any eq 135
access-list 121 deny tcp any any eq 136
access-list 121 deny udp any any eq 136
access-list 121 deny tcp any any eq 137
access-list 121 deny tcp any any eq 138
access-list 121 deny tcp any any eq 139
access-list 121 deny tcp any any eq 445
access-list 121 deny udp any any eq 445
access-list 121 deny tcp any any eq 593
access-list 121 deny udp any any eq 593
access-list 121 deny tcp any any eq 4444

 

[baddos]

VladJ... you forgot the access-list 121 permit ip any any at the end

 

[bell1996]

Are you doing NAT or PAT??? Network Address Translation versus Port Address Translation. If you're PAT, how many devices sit behind the firewall???

 

[vipergg]

I would turn Flow switching and see if there is one or more addresses that appear to be infected , you can look at all the ip flows by doing a show ip route-cache flow .

 

[Aurele]

I would also decrease the NAT timeouts... that wont only decrease overall memory usage from the NAT pool but also be less of a load overall on the router's processor. Saying that, there will be spikes in the CPU processes when the NAT entries expire and get refreshed but like I said, overall it will be lower.

 

[tecnikall]

Can you get a show ver, show mem sum, show buffers and show proc cpu? It could be a slow memory leak on the existing ios regardless of the process which calls for memory.