DHCP server sometimes not found

Gavin McCullagh gmccullagh at gmail.com
Sun Dec 14 22:42:04 GMT 2008


Hi,

On Sun, 14 Dec 2008, Sergio Dicandia wrote:

> I'm finishing our new computer room with 12 thin clients and a 8.041
> Edubuntu server. Everything seemed fine on the first clients I tested,
> but I just found I can start no more than 4 or 5 at the same time.

> The other ones just wait for a DHCP to give them a valid IP address, and there's no way to obtain it.
> I checked cabling and switch, but it's just a matter of who come first: the first 4 (or 5) clients just get their IP, the other ones don't.
> Consider that in my /etc/ltsp/dhcpd.conf I put the correct MAC addresses to assign fixed IPs, and they work fine for the first clients starting.
> 
> Looks like somebody had the same problem, while everything worked fine in 7.10 with LTSP 4.2:
> http://209.85.129.132/search?q=cache:Jj3ycleLzasJ:sudan.ubuntuforums.com/showthread.php%3Ft%3D830748+edubuntu+dhcp+problem&hl=it&ct=clnk&cd=8&gl=it&client=firefox-a

Could you login to the server and run:

	sudo tcpdump -n -i eth0 udp port 67 or port 68

(you might need to change eth0 to eth1 if that's your network interface
which faces the thin clients) then boot the clients in turn.

What you should see is the thin clients making dhcp requests and dhcp
responses going back from the server.  If the client requests don't get to
the server, that'll be clear. Whether the server replies should also be
clear.  Once you know this, it'll be easier to tell where the problem is.

Gavin




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