Any further word on the more in depth explanation?
Interested from both a customer perspective and a technical perspective
- good to learn from these things.
We, at Massey University had a similar situation about 18 months ago. As
it may not be the same, I will describe it as it took us quite sometime
to work out what had happened.
We had a contractor working on a cabinet one night and when he removed
two fibre patch leads, he didn't have any caps for the second lead so
thought it would be OK to simply plug the lead back onto the panel hence
sealing both plugs and sockets. Unfortunately, he connected two trunk
ports together in our core, one was using 802.1q the other ISL. The
result was that we had a flood of traffic across the campus and a large
portion of our switches, basically Cisco 2950s or better shutdown their
The contractor, in the meantime was totally unaware of anything being
amiss and restored the leads to their correct positions. This was about
3am. When we arrived at work later that morning, large portions of the
campus where 'dead'. We had to visit dozens of cabinets and reset
switches to get things back up. We eventually worked out what had
happened but it was a mystery until we talked with the contractor.
The moral of the story seemed to be that spanning tree does work when
one creates a loop by connecting an 802.1q and ISL trunk together.
Glen and Rosanne Eustace
GodZone Internet Services, a division of AGRE Enterprises Ltd.
P.O. Box 8020, Palmerston North, New Zealand 4446.
Ph: +64 6 357 8168, Fax +64 6 357 8165, Mob: +64 21 424 015
"A Ministry specialising in providing low-cost Internet Services
to NZ Christian Churches, Ministries and Organisations."