And to ask you who else has come across the danger to corporate networks posed by the convenience of auto-crossover ports.
I had this at a middle school I do work for, One little darling student did exactly this.
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It is annoying that such a thing can happen, but to be honest it's no worse than in the old days of a missing t-piece or a cable fault, bringing down a whole coax lan.
True, those were the days. But the Base-T system has been so comparatively rock-solid reliable and proof against all the problems we used to have that it has been a shock to find that it is so easily compromised. And the problem has only arisen with the more recent equipment!
You should be using spanning tree protocol (sometimes called spamming tree protocol when it breaks) which should allow these kind of redundant links that you are creating. Indeed redundant links should be/are a good thing.
Yes, redundant links are, I am building up a number, and I have looked at STP. The main reason I haven't used it is that I prefer the idea of subnets, routed, RIP and routers instead: routers based on multi-port FreeBSD boxes. I don't see how STP (or subnets) cure this switch-jamming problem, except that the more intelligent the device the more capable it is of preventing the jam from spreading back onto the network spine. However, we have some quite large (multi-building) branches containing hundreds of outlets that are all within the same easily-jammed area.
Luckily I don't yet have a large number of auto MDI/MDIX switches and am hoping to obtain more older models, which are immune to this problem because normal users don't possess crossover leads.