I have discovered slow performance in various portion of my network accessing network drives and server side applications.

When I logged into the switch providing access for these users I ran a show interfaces status which displayed all of the interfaces and their link speed. Most of which were 100Mb/s.

The switch is capable of Gigabit speeds. I also noticed that when I connected a Gigabit 5 port switch in my office to re-image a few machines with Windows 7; the link light for Gigabit never came on. My IT Manager (the other 50 % of our IT Dept.) decided to take the network jack off of the wall and we discovered it was a CATEGORY 4 CABLE!

We then proceeded to delve deeper into the issue with some handy Cisco show commands; namely show mac address-table and it shows us every MAC that has ever been connected to the interface.

Long story short I want an easy way to determine link speeds and their associated MAC addresses so we can determine which offices were terminated in Category 4 and or workstations that don't have Gigabit Ethernet Cards. We have patch cords to replace the ones that we found in the network closet next week to have as little downtime as possible.

Thanks in advance for any advice.

  • poke around with show interface on your switch. You can get it from there.
    – Dan Pritts
    Sep 6, 2013 at 19:56
  • That's all well and good but you haven't correlated the cabling to your network slowdowns, which is an all too common occurrence during troubleshooting. You assume that the cabling is the cause of your problem but you haven't provided any evidence to support that assumption. My point being, don't chase down what could turn out to be a red herring before you collect and analyze the evidence to support your assumption.
    – joeqwerty
    Oct 9, 2013 at 0:45

1 Answer 1


If you do:

#show interfaces status

You'll get an output of every interface on the switch.

If you do:

#show mac-address table

You'll get an output of every interface with the MAC addresses of whatever is communicating on those ports.

If you do:

#show ip arp

You'll get an output of every interface with the IP addresses of whatever is communicating on those ports.

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