MavEtJu's Distorted View of the World

Monitoring disabled ports on a C3560

Posted on 2007-09-19 13:00:00
Tags: Cisco, Networking, SNMP

When you try connecting strange little switches and hubs to a Cisco 3560 PoE switch, your port might end up in "err-disabled" state:

Gi0/41    **IP Phones & PCs* err-disabled 8          a-half   a-10 10/100/1000BaseTX

cisco#show interfaces gi0/41
GigabitEthernet0/41 is down, line protocol is down (err-disabled)
That port is unusable until the end of time, or until somebody manually shut and no-shut it.

Having experienced this once or two, it's a pain in the bottom and since I'm obsessed about monitoring, I tried to find out how to determine this remotely:

RFC1213-MIB::ifDescr.10141 = STRING: "GigabitEthernet0/41"
RFC1213-MIB::ifType.10141 = INTEGER: ethernet-csmacd(6)
RFC1213-MIB::ifMtu.10141 = INTEGER: 1500
RFC1213-MIB::ifSpeed.10141 = Gauge32: 10000000
RFC1213-MIB::ifPhysAddress.10141 = Hex-STRING: 00 16 46 B6 DC A9 
RFC1213-MIB::ifAdminStatus.10141 = INTEGER: up(1)
RFC1213-MIB::ifOperStatus.10141 = INTEGER: down(2)
RFC1213-MIB::ifLastChange.10141 = Timeticks: (3564555759) 412 days, 13:32:37.59
ifAdminStatus is up, but the "show interface" says it's down.

So nothing! There is no way to find an interface in the err-disabled state via SNMP!

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From: Mark Nagel
Posted on: 2008-12-24 12:27:47
CommentThis is now possible in recent images that support the CISCO-ERR-DISABLE MIB, available since at least 12.2(37)SE. Amazing it took that long to get such a useful bit of information via SNMP, though.

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