[c-nsp] What happens during the "shutdown" and "no shutdown" to a 1000BASE-LX10 port

[Mack McBride]

Shut/no shut can fix a multitude of transient faults.

Doing analysis after the fact is extremely difficult.

Mack

-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Peter Rathlev
Sent: Thursday, August 11, 2011 4:50 AM
To: Martin T
Cc: cisco-nsp at puck.nether.net
Subject: Re: [c-nsp] What happens during the "shutdown" and "no shutdown" to a 1000BASE-LX10 port

On Thu, 2011-08-11 at 00:56 +0300, Martin T wrote:
> Gi0/24   -> Brocade  connected   trunk    a-full a-1000 1000BaseLX SFP

When it says "connected" it's not error-disabling as others have tried
pointing out.

> I'm just curious, what might happened and how did the "shutdown"/"no
> shutdown" improve the situation? Or is it impossible to analyse such
> problems(afterwards)?

I'm not sure how Brocade does, but if it was a Cisco switch in the other
end it could be that e.g. STP loop guard had blocked the link. A link
down/up event would make STP recalculate and thus open the link again.

Another possibility might be a unidirectional link, though I can't see
how forcing down/up would resolve that.

I think the problem is easiest to determine with access to the Brocade
switch. Do the people managing that switch not have logs of some kind to
consult?

-- 
Peter


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