If you are using the Cisco VPN client 3.7.x with the GUI, you might have noticed that when it is installed, your network won't return from sleep. After having to reboot every time this happened, I got frustrated. Apparantly this problem is fixed in version 4.x of the client, but you can't get it from Cisco unless you have a Cisco support contract, and our network security guys don't want to upgrade to 4.x just yet. So aside from black hat methods, I am stuck with 3.7.2.
If you lose your network after waking from sleep, here is an easier way to get it back than a reboot. Run these two commands in Terminal (or your favorite terminal application):
sudo ifconfig en0 down sudo ifconfig en0 mtu 1500 upMost Macs with one network card should have their card at en0. If your card is not at en0, substitute which interface you want to reset. I am assuming that if you have multiple ethernet interfaces, you can figure out which one is which.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20030815150328437