Error message

[henryabrams63]

Can someone explain this error message to me. 

: %IP_VFR-3-INVALID_FRAG_LENGTH: GigabitEthernet0/1: fragment length invalid - received from 10.x.x.x

IP_VFR-4-FRAG_TABLE_OVERFLOW: GigabitEthernet0/2.5: the fragment table has reached its maximum threshold 16

[Mark Malone]

You can fix this by setting it to 64 , the default is only 16 per interface you have hit the max fragments that can be re-assembled in the buffer , the max is around 1024 but you don't want it to high or you could introduce issues , packets come in fragmented bascaily and the router/interface can reassemble so many in its buffer before it maxes , if you are maxing it you need to increase it

Under the interface set the below   

ip virtual-reassembly max-reas 64

[henryabrams63]

Thanks. I really help out alot. 

[Mark Malone]

great glad you got it sorted

[shafik.khan9]

Hi Mark,

I m also facing the same issue with my Cisco 881 4g router, Just wanted to know what is the reason for this error, Is increasing the thresholds size only the solution.

[Mark Malone]

one of the reasons it can be from an attack

http://www.certvideos.com/virtual-fragment-reassembly/

https://cciepursuit.wordpress.com/2007/10/07/ip-virtual-reassembly/

[dendenden]

Hi Mark,

I`m having the same issue, and even if I set the maximum reassembly threshold to 1024, it still reaches on that level which might cause our 2901 router to increase its cpu util to 99% then thats the time vpn and sometimes internet traffic is affected. The only solution that we do now is to reboot the router and after sometime issue still happens again.

May I know what`s the other option to solve this issue?

Thank you