Mandar, Stephen, and others battling with or considering dual DHCP servers,
While configuring the LTSP DHCP server to only hand out addresses to particular MAC addresses will save the Windows machines from trouble, this solution requires that his existing Windows DHCP server also hand out fixed IP addresses (to prevent the diskless clients from occasionally getting a response from the Windows DHCP server first). If the administrator is resistant to change and is handing out dynamic IP addresses, then this does not solve the entire problem. It's not just a problem of having the diskless clients getting a response from the Windows DHCP server during the initial Etherboot DHCP query, either. There's also the dhclient query when the kernel boots! FYI, depending on how the DHCP client is configured, it can wait a pre-determined amount of time and then choose from multiple DHCP responses. The default behavior of immediately responding to the first offer is what leads to seemingly random behavior (sometimes one server answers first, sometimes the other). I believe there were some relevant posts a short while back on the ltsp-developer mailing list. I think it was Ken Yap talking about how you could place a special string in your dhcpd.conf file to allow it to identify itself to Etherboot clients as their preferred server. There was also a way to instruct the Etherboot clients to look for that string. Here's the link to the message and the relevant quote: <http://sourceforge.net/mailarchive/forum.php?thread_id=683572&forum_id=2542> "For people who have to coexist on a network already running a DHCP server, Etherboot has the REQUIRE_VCI_ETHERBOOT option which works well for selecting only the Linux DHCP server for the reply. Unfortunately dhclient in LTSP will get its info from any DHCP server. dhclient.conf is apparently flexible enough to implement the same filtering scheme as Etherboot. I'll work on some changes to root/linuxrc to implement this scheme. It will be triggered by the existence of a kernel parameter of DHCP_VCI=Etherboot-5.0 (in option-129) so it will still work in the normal case." A follow-up message includes that patch to the root/linuxrc and a config example. <http://sourceforge.net/mailarchive/forum.php?thread_id=690001&forum_id=2542> According to Ken, the patch would've required a more recent version of dhclient, however. Just an hour later, Ken posted an alternative solution, which would work with existing versions of dhclient: <http://sourceforge.net/mailarchive/forum.php?thread_id=690149&forum_id=2542> "Here's a lower tech approach which can be deployed right away. If DHCP_REJECT is defined in option 129 as the IP address of a server to ignore, then dhclient will not accept replies from it. So you would set it to the IP address of the rival DHCP server. This works with the dhclient in current LTSP initrds." I don't know if either linuxrc patch made it into the LTSP 3.0.4 kernel to support this, though. Perhaps Jim can bring us up to date on this. In any case, it seems that it is absolutely possible to have LTSP w/ DHCPD coexist with another DHCPD on the same network. Whether the ability to do that is pre-built into the new LTSP kernel is another question. Jason > From: "Stephen Berry" <[EMAIL PROTECTED]> > Subject: Re: [Ltsp-discuss] 2 DHCP Servers on same segment > Date: Wed, 10 Jul 2002 13:31:17 +0100 > > It is possible to have 2 DHCP servers on one segment. That is what we are > doing here. Our Win2k server hands out fixed DHCP addresses which means that > each client will always have the same IP address. Any unused IPs are locked > out so that they cannot be used. The LTSP server also dishes out IPs to our > LTSP clients with a fixed IP for a specific MAC address. ------------------------------------------------------- This sf.net email is sponsored by:ThinkGeek Two, two, TWO treats in one. http://thinkgeek.com/sf _____________________________________________________________________ Ltsp-discuss mailing list. To un-subscribe, or change prefs, goto: https://lists.sourceforge.net/lists/listinfo/ltsp-discuss For additional LTSP help, try #ltsp channel on irc.openprojects.net
