Checking for port errors on Cisco Switches

Written by James McDonald

May 26, 2016

Recently had a macbook pro which had a network dongle that was very hot and the network connection stopped working.

Found that the dongle was sending garbled signal down the wire and the Cisco switch shutdown the port.

# all status
show interfaces status 
# port shutdown due to line errors
show interfaces status | include err-disabled
# not connected to a live device
show interfaces status | include notconnect

Sample output (doesn’t show err-disabled ports)

Port      Name               Status       Vlan       Duplex  Speed Type
Gi0/12    "Kobi CCTV"        connected    20         a-full a-1000 10/100/1000BaseTX
Gi0/13                       connected    1          a-full a-1000 10/100/1000BaseTX
Gi0/14                       notconnect   1            auto   auto 10/100/1000BaseTX
Gi0/15                       connected    1          a-full  a-100 10/100/1000BaseTX
Gi0/16                       notconnect   1            auto   auto 10/100/1000BaseTX
Gi0/17                       notconnect   1            auto   auto 10/100/1000BaseTX
Gi0/18                       connected    1          a-full  a-100 10/100/1000BaseTX
Gi0/19                       connected    1          a-full   a-10 10/100/1000BaseTX
Gi0/20                       notconnect   1            auto   auto 10/100/1000BaseTX
Gi0/21                       connected    1          a-full  a-100 10/100/1000BaseTX
Gi0/22                       notconnect   1            auto   auto 10/100/1000BaseTX
Gi0/23                       connected    1          a-half   a-10 10/100/1000BaseTX

http://www.cisco.com/c/en/us/support/docs/lan-switching/spanning-tree-protocol/69980-errdisable-recovery.html

Just posting this here as a reminder for next time.

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