Two readers report that the Spanning Tree Protocol used in Cisco and other switches is responsible for slow Mac DHCP assignments. Eric Stein reports:
Turn off spanning tree for the ports connected to Macs or insert dumb switches between the Macs and the dysfunctionally smart Cisco hardware.
John Lockwood in the United Kingdom says this is an old problem:
This suggested fix basically involves turning "Spanning Tree Protocol" off for the ports that Macs are connected to. Problems between Macs and Spanning Tree have existed for many, many years and even pre-date Mac OS X. For example see this Apple article from 2003.
It does not merely apply to Cisco switches either, I had a relatively recent case that involved some NetGear managed Gigabit switches.
Port host command for slow network connection for OS X Cisco switches
Thursday, August 27, 2009
Rich Dagel has another suggestion for the problem of slow Mac DHCP assignments through Cisco switches:
Use to have the same issue. Check the portfast. Also, a big one for us was port host command. It would sometimes take up to 60 seconds for a Mac to get an IP address before we used the port host command.
We've previously reported other suggestions for this problem. If you have one