From: Todd, Douglas M. (DTODD@PARTNERS.ORG)
Date: Thu Feb 21 2008 - 16:28:36 ARST
My take:
The problems are NOT always fiber related. We have had many problems where udld
has saved us due to hardware interface problems.
aggressive is faster and works w/tx ports, normal does not...
Aggressive WILL errDisable a port.
normal will not, but will continously cycle the port to re-establish
connectivity.
Thus if you have no redundancy normal may save you a trip to the closet for a
small crc issue. (unless you use udld error timeout). If you do have redundancy
then aggressive is the way to go to prevent periodic loops/outages which happen
when the link goes unidirectional and is cycled through STP.
UDLD under normal mode (non-aggressive) works on fiber based ports only with a
timer set as 15sec
UDLD under normal mode works with the autonegotiation feature in L2 to determine
if the port is up/down/indetermined.
Aggressive uses "echo" type system for better response and link validity
UDLD aggressive works on TX ports and it times out after 8 tries.
:)
Douglas
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of Joseph
Brunner
Sent: Wednesday, February 20, 2008 3:14 PM
To: 'Nambi Appachigounder'; ccielab@groupstudy.com
Subject: RE: Question on UDLD...
Just get an alert its pretty useless... but if you ONLY had one link between the
switches, would you want aggressive mode, which will shutdown the link?
Better to know your fiber sucks, than not know... that's my angle...
-Joe
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of Nambi
Appachigounder
Sent: Wednesday, February 20, 2008 9:31 AM
To: ccielab@groupstudy.com
Subject: Question on UDLD...
Hi All,
I could not get the clear idea about UDLD normal mode.
It is defined like this.
"In normal mode, if the link state of the port was determined to be
bi−directional and the UDLD information times out, no action is taken by
UDLD. The port state for UDLD is marked as undetermined. The port behaves
according to its STP state."
Is the end effect not as bad as not having UDLD?
What do we gain with this?Can anyone please help me.
Thanks
Nambi
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