Investigating output drops on a 3750x stack..

Two interfaces that connects to a file server (broadcom teamed interfaces) shows some output drops when i transfer large files. The utilization of the ports are still below the 1Gb port speed.

As far as i can see a 3750 has 2 asics (sh platform port-asic version). I think the problem must be on the asic because the port is not fully utilized (as far as i can see). When this is the case would i see more drops on interfaces that are connected to the same asic?

Is there a way to see what ports are mapped to what asic?

In each stack member there is a 10Gb card (uplink to the core). Does this card have 1 asic dedicated for this card?

I read things about microburst and i wonder what i can do to determine if this is the case? Can wireshark help me with this?

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1 Answer 1


I hope this link is helpful to you:


sh platform pm if-numbers

The output did not format very well.

The ‘port’ column lists the asic/port number (can use this to balance ports by splitting devices onto different ASIC although some platforms only have two!)

Do you have QoS enabled on the switch? If so the port buffers are shared between the four queues although the queue-set configuration can be increased to 3200%.


  • 1
    +1 for QoS. Even if mls qos is not enabled, the default settings can cause drops at well under line rate. Take a look at Egress QoS on Cisco's support forums. The document is older, so it's specific to the original 3560/3750 and 3560E/3750E, but the 3560X/3750X are still pretty close architecturally. Oct 4, 2013 at 1:07

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