Gigabit network dchp a bit slow

[IcedEarth]

I have replaced all the 10/100 switches at my school to Gigabit as I have recently installed a new server with two Gigabit NICs in it and its all nice and fast except....

 

When my windows xp machines are getting an IP address, it seems to be taking a while longer than when I had my 10/100 switches.

 

When I took my laptop in over the holidays to do some work, it took what seemed forever to get an IP address and I have noticed it at the end of last term on the teachers laptops.

 

Its not a show stopper, but it just seems a bit odd, does anyone have any ideas for investigating further?

[FN-GM]

what make of switches are they? Also does your new server do the DHCP?

 

Z

[SYNACK]

The chances are that your new gigabit switches are either fully or partially manages and are probably running STP (spanning tree protocol) on each port in full discovery mode which will isolate a newly plugged in system for a signifigant amount of time while it checks to make sure that there is not a switching loop present on that port.

 

Your best bet would be to go into the configuration of each of the switches and set spanning tree to portfast/client pc mode which will make isolate the ports for a much shorter time and run less thorough checks as it expects a client instead of another switch. Your delay time for this setup is around 1 to 5 seconds.

 

Having the switches in full STP mode will also break things like software deployment via GPO as the operation times out before the machine has access to an ip address.

[jcollings]

I would tend to agree with Synack. We replaced our switches recently with some 3com managed ones and had a similar issue. STP was turned on on all ports - turning it off seemed to cure the problem.

[IcedEarth]

Yeah they are 3COM, ill have a look at configuring that STP protocol. (Never heard of it before!!) The switches have management ports I think, if not Ill find a way. Failing that ill get my network support company out, they put them in after all.

 

Thanks all for the advice on the Sunday night, top job!! I can go on holiday and relax now.

Edited August 17, 2008 by IcedEarth

[amfony]

if you didnt have any multiple paths from any two points i *guess* you could safley disable STP on all switches?