MavEtJu's Distorted View of the World - 2007-09

Monitoring disabled ports on a C3560
The white dot on the television
Degausing CRT based monitors
Raritan Dominion KX-II KVM switch

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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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The white dot on the television

Posted on 2007-09-04 22:45:00
Tags: Lost memories

And the previous article reminded me on an old television I saw this weekend. When you turned of an non-digital television, the leftover electrons in the electron beam gave a nice bright white spot in the middle of the screen.

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Degausing CRT based monitors

Posted on 2007-09-04 22:00:00
Tags: Lost memories

Today I heard a sound I hadn't heard for a long time: The *KATSJONK* when you turn on a CRT based monitor. It reminded me of the degause button on the huge 21" monitors I once had at work.

The auto-adjust button on my LCD monitor doesn't really give me the same adrealine rush...

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Raritan Dominion KX-II KVM switch

Posted on 2007-09-04 14:00:00
Tags: Networking, SNMP

We have a new remote accessible KVM switch. Of course we monitor from it as much as possible, including the sysUptime (an excellent way to catch devices which reboot within a one minute period). Only...

Only, the sysUptime gives an interesting answer:

DISMAN-EVENT-MIB::sysUpTimeInstance = Timeticks: (270416251) 31 days, 7:09:22.51
DISMAN-EVENT-MIB::sysUpTimeInstance = Timeticks: (4291368169) 496 days, 16:28:01.69
DISMAN-EVENT-MIB::sysUpTimeInstance = Timeticks: (957) 0:00:09.57
DISMAN-EVENT-MIB::sysUpTimeInstance = Timeticks: (1163) 0:00:11.63
DISMAN-EVENT-MIB::sysUpTimeInstance = Timeticks: (1334) 0:00:13.34
DISMAN-EVENT-MIB::sysUpTimeInstance = Timeticks: (4291368783) 496 days, 16:28:07.83
DISMAN-EVENT-MIB::sysUpTimeInstance = Timeticks: (4291368895) 496 days, 16:28:08.95
DISMAN-EVENT-MIB::sysUpTimeInstance = Timeticks: (4291369006) 496 days, 16:28:10.06

It looks good for a couple of seconds, but then... Disabling NTP resolves these symptons.

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