what constitutes a runt ?

[cottert]

What packet size is considered a runt in the output of a 'sh interface' command on a 3750?

My question arises due to the fact that vendor is sending very small packets, some only 14 bytes while others may be only 35, 42 and they believe our 3750 is dropping them but commands like 'sh interface' or 'sh platform asic ....' do not indicate any packet loss.  Are there any other commands to use which can help identify the problem?  

[Peter Paluch]

Hi,

A runt is a frame whose total length (DMAC, SMAC, Type, Data, FCS) is smaller than 64 bytes.

My experience has been that while these switches recognize undersized frames as runts, they may still decide to forward them and not drop them. Unfortunately, I won't have access to lab till the next week to verify whether this is still the case.

Some of the following commands may give you sligthly more info:

show interface ... controllers
show interface ... counters
show interface ... counters errors

My 2 cents...

Best regards,
Peter