[AusNOG] Outage that costs Millions

[Craig Meyers]

I'm hearing that a card failed in Longsdale exchange which affected
multiple links, which initiated a flood of spanning tree messages and
triggered loop prevention mechanisms, and Telstra had to restart links
in error-disabled state.

In a nutshell, which is what people on this list guessed anyhow.

Hope this helps.

-- Craig


-----Original Message-----
From: ausnog-bounces at lists.ausnog.net
[mailto:ausnog-bounces at lists.ausnog.net] On Behalf Of Sean K. Finn
Sent: Thursday, 1 July 2010 12:51 PM
To: 'Adrian Chadd'; 'Narelle'
Cc: 'ausnog at ausnog.net'
Subject: Re: [AusNOG] Outage that costs Millions

This might be why STP calls it 'Flooding' BDU's. :)

Nothing.. Nothing..Nothing.. SMAK! WHOA! Where the heck did all this
traffic come from.. Damn.. Nothing.. Nothing... Nothing..

Sounds like the Dam Burst and took the Bridge down river with it... (Bad
Pun).

Sean.

> You can start having fun things occur like your STP never hitting 
> steadyish state because of things like flapping roots, and these can 
> occur because of full pipes triggering packet loss which causes 
> differing paths to be preferred, then lots more learning needs to 
> occur; then ARP timeouts may occur and retransmission of ARP happens; 
> then your switch/router CPU maxes out and you miss a link/routing
protocol heartbeat; then more flaps occur, etc, etc.

> This happens even now in the IP world. Why oh why do you think 
> spanning tree is any different? :) Adrian


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