dhcpd capacity

Benjamin Wiechman benw at meltel.com
Wed Nov 7 14:45:30 UTC 2007

How do you check to see if syslog is configured to write synchronously or

Ben Wiechman
Wisper High Speed Internet
Office: 866.394.7737
Direct: 320.256.0184
Cell: 320.247.3224
ben at wisper-wireless.com

-----Original Message-----
From: dhcp-users-bounce at isc.org [mailto:dhcp-users-bounce at isc.org] On Behalf
Of fadey
Sent: Wednesday, November 07, 2007 2:46 AM
To: dhcp-users at isc.org
Subject: RE: dhcpd capacity

Yes, I did that. In a lot of cases a timeout occurs before a cable modem
receives an OFFER (and so a new DISCOVER is being sent again). Sometimes
an OFFER comes through, but again a timeout occurs before a cable modem
manages to receive an ACK. So the process repeats over and over.
Occasionally (aprox. once per 1-2 minute) some lucky cable modem manages
to get all the info and come online. So in an hour or so the network is
online again.
What I currently do to coop with the problem is restart the dhcpd once
per 8-10 seconds when the total reset occurs. That helps. Just after the
reset a couple of cable modems get their info. So resetting speeds up
the total network bootup to 20 minutes or so.

> Have you turned on debugging on your CMTS to make see if the DHCP replies
> are at least getting processed there?  Have you been telneted into your CM
> on the LAN port side to see if it's getting the DHCP replies, or if there
> any more information?  Ideally you would have a DOCSIS protocol analyzer
> from Sigtek.
> Frank
> >
> > logging : is syslog configured to write logs synchronously ? If so,
> > then this slows things down quite a bit (every log created results in
> > a disk write). Setting this to async helps quite a bit.
> >
> > Also, some people have experimented with putting various things on
> > ram disk - but it may not be safe against reboots.
> >
> >
> >

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