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Webcast-Catalyst9k
New Member

Pin-pointing the culprit

Hi experts,

Does anyone know how to or what command in 3560 switch to use when you see a high utilization on a specific port to see what's connected to it and tell if what device it is? i.e. ip phone, pc.

Or there's no other way than checking it physically?

tnx

1 ACCEPTED SOLUTION

Accepted Solutions

Re: Pin-pointing the culprit

If you are seeing CDP, then it is unlikely to be a PC. If this is a user port that you are seeing a device with CDP on, it is likely to be a phone.

Is the name of the device known, or is it something like SEP0013C354F8E3? If so it is likely to be a phone.

If you cannot see an IP address, it may mean the device does not have one, o it may not be accessible via this interface/ If you add a sh cp nei det of the device, we can probably help further.

Paul.

6 REPLIES

Re: Pin-pointing the culprit

sh mac-a int will show you the mac addresses of devices

sh ip arp | inc will let you convert that to an IP address.

sh cdp nei det will tell you if it is a Cisco device with CDP (eg a phone) on the interface.

Paul.

Blue

Re: Pin-pointing the culprit

Is Cisco going to add NetFlow support to the non-modular switches any time soon?

New Member

Re: Pin-pointing the culprit

thanks paul.

I doesn't show anything to me. what could that mean?

tnx

Re: Pin-pointing the culprit

sh cdp nei showing nothing on a port means that either there is no Cisco device attached (eg a phone) or it has CDP disabled

sh mac-a showing nothing on a port means the switch is not seeing traffic from valid source mac addresses on that port.

P.

New Member

Re: Pin-pointing the culprit

the cdp is enabled as i can see other connected devices but the strange about it, i can see the mac address but cannot see the ip of the host that is connected on that specific port! Could that mean that a pc is not a valid source of a mac address? then why could it indicates alot of input errors?

Pls. enlighten me up, just a newbie in this field!

tnx

Re: Pin-pointing the culprit

If you are seeing CDP, then it is unlikely to be a PC. If this is a user port that you are seeing a device with CDP on, it is likely to be a phone.

Is the name of the device known, or is it something like SEP0013C354F8E3? If so it is likely to be a phone.

If you cannot see an IP address, it may mean the device does not have one, o it may not be accessible via this interface/ If you add a sh cp nei det of the device, we can probably help further.

Paul.

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