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I'm in the process of replacing some switch blades and i'm looking through the show port usage command on the older catos switches.

I'm struggling to understand the output for the show port usage command

(enable) show port usage 6/47

Port  Status          Last-Transition-Time
...
6/47  connected       Mon Sep 16 2013, 16:11:25    <------

That is my machine but I've restarted my machine since Sept 16th numerous times. Does restarting my machine not affect the transitioning which assume refers to rstp? (We're looking at this to see what ports we can safely unplug.

We do have a port tracking tool, but I'm cross checking this on the switch to make sure.

These ports have portfast enabled which is what I'm thinking is the cause of this, but there is no information available that describes this command.

Any help would be greatly appreciated.

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    A lot of computers these days keep an ethernet link up even when you reload (basically it stays linked as long as the motherboard has power). Could you physically unplug the PC for about five seconds and validate that the link status counter indicates a recent transition?
    – Mike Pennington
    Nov 8, 2013 at 10:47
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    I've just realised that some ports go through Cisco phones which explains why it hasn't transitioned. (I went to unplug and then noticed that's the setup)
    – Oli
    Nov 8, 2013 at 10:51
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    By the way if you have a Cisco phone attached to that port you should be able to see the phone with CDP. Use show cdp neighbor to find the phone
    – Mike Pennington
    Nov 8, 2013 at 13:46

1 Answer 1

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As you found, the port is plugged into a phone; so until the phone cycles the port will stay up.

Regarding the portfast command; when a switchport comes up, spanning-tree moves through a series of states to bring the port up. Legacy spanning-tree took 15 seconds in the Listening state and another 15 seconds learning. During that time, the port cannot actually transmit traffic. portfast is a shortcut to make the port transition to a forwarding state very quickly, which is what you want as long as no switches are connected to the port.

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