I am currently managing a large datacenter spine-and-leaf topology. On our leafs, we use stacked 3750-X switches.

I want to know how much bandwidth is currently going across the stack links (currently 6 switches in the stack, about to be 8). We currently use 10GB uplinks to our spine using a SM module (only two links currently up to the spine from different switches in the stack). I can look at the total available bandwidth (which is 32Gbps) but not what is being used. I tried to graph the stack links in Cacti but nothing is showing up using the standard graphs.

Is there a way to tell current bandwidth or dropped frames due to oversubscription? Can I graph this is Cacti to monitor for a period of time to tell peak usage?

Not finding much information on Google right now, thanks.


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2 Answers 2


I do not know a direct way to show the exact bw utilization per stack port, however you can show the total number of frames sent by each stack member to the stack ring by using the command "show switch stack-ring activity", you can also know the overall utilization of the stack-ring using the command "show controllers utilization" but it wont show you the percentage of each stack port.

Reference: Catalyst 3750 Command Reference

  • 1
    In addition, StackWise Plus (on the X and E versions of the 3750) enables local switching, which means that packets do not have to traverse the ring order to be switched if ingress and egress port are on the same switch. Have you tried approaching this by measuring your north/south traffic rate, minus the traffic switched to the local ports on the switch with the uplink? By default, the remainder would be going over the stackwise ports. Additionally, spatial reuse means that a packet destined to another switch takes the shortest ring-route, and does not have to traverse the whole ring
    – nicotine
    Jan 12, 2015 at 19:51

You have the 3750X, so I would have thought this will be Stackwise PLUS which offers 64Gbps Ring bandwidth and local switching. I am unaware of how to monitor the stack ring bandwidth utilisation besides the show switch stack-ring activity command.

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