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-------- Original Message --------<br>
Subject: Re: slow dhcp on 1G backbone.<br>
From: Dean Montgomery <a class="moz-txt-link-rfc2396E" href="mailto:dmonty@sd73.bc.ca"><dmonty@sd73.bc.ca></a><br>
To: Users of ISC DHCP <a class="moz-txt-link-rfc2396E" href="mailto:dhcp-users@lists.isc.org"><dhcp-users@lists.isc.org></a><br>
Date: Friday, July 24, 2009 3:23:15 PM<br>
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<pre wrap="">Where are these 12 second delays in your capture/syslog? Are the
clients sending requests that are not seen by the server?
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<pre wrap=""><!---->
This could be the case - dhcp traffic is not traveling over the LAN in a timely manner. and/or dhcp traffic is being lost by the Procurve switches.
Just before bios pxeboot & kernel's dhcprequest, the link-light turns off then on again. It may be the switch is slow trying to re-negotiate link speed with the client.
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This is very likely the problem. Some network cards/drivers reset the
link at different stages of bootup and this resets the link. In these
cases it is crucial that the port initializes and is able to pass
traffic prior to DHCP requests to prevent lost packets. Does your PXE
boot show that requests are being made and timing out, or is it not
that verbose?<br>
<br>
Running standard spanning tree, most ports take 30-45 seconds to come
up, portfast reduces this to ~ 10-15 seconds in my experience. Again
there are other things besides spanning tree that could be delaying the
time a port is ready to pass data (such as VLAN, trunking, or
aggregation negotiation protocols).<br>
<br>
Can you try putting a hub or linksys switch (whose ports come up
basically instantly) between the PC and your HP switch to see if that
speeds up the DHCP process?<br>
<br>
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<pre wrap="">==
I tried changing the switch configured speed on port16 from "Auto" to "100Fd". This made the client on port16 continually loose it's link.
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as mentioned previously, both ends need to be set to auto or manual -
mixing will usually cause problems (duplex/speed mismatches)<br>
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<pre wrap="">
==
* All switches have the latest firmware.
* All switches have factory default settings (except we turn on spanning tree). We tested spanning tree off earlier and it is not the cause.
==
NOTE: This slow dhcp has been an "ignored issue" for 4 years in many schools. I now have a bit of free time to see if it can be resolved.
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