How to tell if anything is connected to a switch port

Answered Question
May 6th, 2009

Hi,

I've got a basic problem where I can't tell for sure whether a workstation is plugged into a switchport or not. I know that a port will say "notconnected" when running "sh int status" but how do I know what the workstation hasn't been turned off and it reporting the connection incorrectly. Any ideas would be appreciated.

Thanks

Dan

Correct Answer by Jon Marshall about 7 years 9 months ago

Dan

Short answer is you don't really. The "notconnected" simply means there is no active device on that port, the key word being active. So a PC, laptop etc.. connected to that port but shutdown will not show up.

Jon

  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 5 (1 ratings)
Loading.
Correct Answer
Jon Marshall Wed, 05/06/2009 - 01:00

Dan

Short answer is you don't really. The "notconnected" simply means there is no active device on that port, the key word being active. So a PC, laptop etc.. connected to that port but shutdown will not show up.

Jon

deepa.muralidharan Wed, 05/06/2009 - 01:08

There is no way of finding if the system connected to the switcport is shutdown.

However, we can check the MAC table entry to see if there ia any entry for the specific port.

{P.S : This mainly depends on the age-out timer configured}

dan_track Wed, 05/06/2009 - 01:46

Thanks for letting me know. So my only way is to visually check.

mlund Wed, 05/06/2009 - 04:00

Hi

You can have a hint if this interface has ever been used.

#show interface

<

Last clearing of "show interface" counters never

<

0 packets input,

<

#show version

<

uptime is 2 years, 20 weeks, 4 days, 22 hours, 56 minutes

<

with theese two commands you can see, no packests have been received in over 2 years.

Of course, this doesn't mean nothing is connected, but it's less likely to be.

If the uptime is shorter, it will be more unsecure.

glen.grant Wed, 05/06/2009 - 09:25

If you are talking a 4500 using the "show interfaces link " will tell you when it was last used .Don't know why they don't use this command on all switches .

Leo Laohoo Wed, 05/06/2009 - 13:50

Hi Dan,

When a host is powered off, the NIC received power from the power point and would continue to light up and you will see a response from the switch. However, if the host has it's power removed, the NIC will "die" and thus the response is "notconnect".

Does this help?

mattkaya56 Wed, 05/06/2009 - 17:21

Hello Dan,

If you know the mac address of the NIC on the host. Try show mac-address-table address - it should display

or show mac-address-table interface

Thanks

Mat

Actions

This Discussion