Seeing output drop and misses buffer in Catalyst 2960S

[zulkarnain]

Hi All.

We have a Catalyst 2960S. We have encountered an issue where there are many PING timeout from the multiple servers connected to the switch to the Gateway (which is at other switch). We are seeing packet drop (output drop) and also a misses buffer. I attached here the output of show interface summary and show buffers. Kindly help to explained. Thank You

[Leo Laohoo]

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@zulkarnain wrote:

multiple servers connected to the switch

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This is to be "expected" because a Catalyst switch is not meant to be (nor designed for) connected to a high-speed server(s).  The port buffer of Catalyst switches are notoriously shallow.  
Without QoS configured properly Total Output Drops will be very, very high.  

[zulkarnain]

Hi Leo.

 Thanks for the reply. As we encounter this just a few days back, before this it is happen to be stable. BTW did you have any interpretation on the output I attached? It would be helpful if I can get the conclusions from there.

[Georg Pauwen]

Hello,

on a side note, you might want to try and tune the buffers. You can start out by doubling the sizes (keep an eye on the switch performance for the impact these buffer increases have):

Configure the below values in global config mode:

buffers small max-free 300
buffers small min-free 40
buffers small permanent 100

!

buffers middle max-free 300
buffers middle min-free 20
buffers middle permanent 50

!

buffers big max-free 300
buffers big min-free 10
buffers big permanent 100