RE: portfast

From: Mikael Abrahamsson (swmike@swm.pp.se)
Date: Sat Jul 07 2001 - 05:23:33 EDT


On Sat, 7 Jul 2001, Andrew Fort wrote:

> Some machines (read: ones that can boot quickly) can timeout for dhcp
> requests irrecoverably before the switchport has gone through the listening
> and learning stages in the spanning tree process. portfast assumes that
> these steps are not required -- the port must be connected to an "end
> station".

I thought this was accounted for in the DHCP specs, that you need to wait
at least 30 seconds before deciding that the dhcp server is unavailable. A
lot of network cards do not do "link-up" until the driver initialises the
card and thus you're in the 30 second wait period when you bring up the
link and then starts asking for dhcp servers.

-- 
Mikael Abrahamsson    email: swmike@swm.pp.se



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