LANE. LAN Emulation -- the ability to stick an instance of any subnet anywhere I want in the network without having to configure a path between all the points (as I would have to with 802.1Q VLAN tagging in an Ethernet network). This is intensely handy for troubleshooting or testing.
Things I will not miss when we got to a Gigabit Ethernet network:
All those little gremlins that come with running a connection-oriented network technology (ATM) on a big honking ring. Things like ATM-attached routers not successfully reconnecting to a site way over there when one of the sites in the middle has a hiccup.
Remote reboots that don't. Nortel had this problem licked in the 4.1.2.x code revs, but it seems to have crept back into the 220.127.116.11 code we're running now: switches with redundant processors (that would be something like 78 of my 85 switches) have a nasty habit of getting hung up on restart every once in a while. That's why my day started back at Naylor today. I did a remote restart on Naylor's ATM switch at 9:30 last night and it came up all weird -- requiring a visit to the site to do a cold boot to clear the problem.
Maybe next Monday (maybe not for months, but that's another topic for another post) we'll know whether the Feds are funding our network upgrade project. That would make a nice Yule present. Yeah.