Hi,
We have a Core switch formed by two physical switches in the Stack form.
We have for each floor, fiber uplinks and so, I enabled UDLD last Friday, to avoid any potential Unidirectional Link.
Everything seemed ok, status shown as Bidirectional.
But on Sunday, ALL these links went down, as error-disabled because of a False Positive detection.
So I searched the net, and found something curious about service-acl(s).
I will show two samples (now working, under test)
hub-cf50-8166#show udld tengigabitethernet 1/0/1
Interface Admin Mode UDLD Mode UDLD Status
--------- ---------- ----------- ---------------------------
Te1/0/1 Enabled Normal Bidirectional
hub-cf50-8166#show udld tengigabitethernet 2/0/1
Interface Admin Mode UDLD Mode UDLD Status
--------- ---------- ----------- ---------------------------
Te2/0/1 Enabled Normal Bidirectional
Configs:
hub-cf50-8166#show running-config interface te1/0/1
channel-group 3 mode active
description "#HUB-CF50-8154 - Te1/0/1#"
udld enable
no service-acl input blockudld
hub-cf50-8166#show running-config interface te2/0/1
channel-group 3 mode active
description "#HUB-CF50-8154 - Te1/0/2#"
udld enable
hub-cf50-8166#show service-acl interface te1/0/1
Service-acl Interface Te1/0/1
Protocol Mode
--------------- ----------
CDP Disabled
VTP Disabled
DTP Disabled
UDLD Disabled
PAGP Disabled
SSTP Disabled
ALL Disabled
hub-cf50-8166#show service-acl interface te2/0/1
Service-acl Interface Te2/0/1
Protocol Mode
--------------- ----------
CDP Disabled
VTP Disabled
DTP Disabled
UDLD Enabled
PAGP Disabled
SSTP Disabled
ALL Disabled
Is possible that the DEFAULT acl blocked at some point UDLD??
Why is the DEFAULT value Enabled, so why is the default to block UDLD? (theorically, because seems to be working...by now)
Is this OK ? Documentation does not advice this...
BTW when this happened I was using v6.3.2.7.
Now I upgraded to v6.3.3.8 and the default behaviour of the ACL seems to remain intact.
Protocol Mode
--------------- ----------
CDP Disabled
VTP Disabled
DTP Disabled
UDLD Enabled
PAGP Disabled
SSTP Disabled
ALL Disabled
Well, thanks!