Frag Table Overflow

[Ricky S]

Hi folks, I have a router that keeps having it's frag table buffer fill up quite rapidly. This router is located at one of our central offices that a lot of other offices connect to via IPSEC VPN tunnels (DMVPN). I raised the bar to 1024 however it still fills up

ip virtual-reassembly in timeout 32 max-fragments 32 max-reassemblies 1024

All routers have an MTU on their outside physical interface of 1492 bytes. All tunnel interfaces are set at 1400 to 1420 bytes MTU.

Is there a way to find out where majority of fragments are coming from? As I have a feeling this is causing an issue where right after a fresh reload I can ping this router with 1500 Byte ping packets but soon after it starts to drop these pings. Only thing I notice at that time is frag table overflow in the log.

Please advise.

Thanks

[paolo bevilacqua · Accepted solution]

Just disable virtual reassembly. It is just source of trouble.

[Ricky S]

Thanks Paolo. That did help a bit but I'm still experiencing packet loss. I just posted another long question in the forum, perhaps you can take a look at that and advise please?

https://supportforums.cisco.com/message/4088971#4088971

Thanks