It was interesting to see a recent post on Joel Spolsky's blog explaining that a recent service outage in their hosting environment was caused by accidentally setting their switch to auto-sense network speed. In the post, he acknowledges that they do normally set the network speeds manually and turn off autonegotiate but that one switch had slipped through the cracks.

Leaving autonegotiate turned on can cause all sorts of sticky problems on a network because during negotiation a switch can drop packets. In an office network this is less noticeable, but in a high load environment it can really toss a wrench into the works.

In fact, as reflected in this post on the short lived CF-Guru blog you can see that this same setting can cause CF to potentially hang and depending on load, eventually fail.

So consider this a friendly reminder. In production environments, peg all the switches and NICs to a set speed.