Re: Thin Clients: No Boot Device (sometimes)

[Ragnar Wisloff <ragnar@skolelinux.no>]

Ralf Gesel|ensetter skrev:
> Am Sonntag, 14. November 2004 20:32 schrieb Ragnar Wisloff:
>
> > No, just leave them. No network card has a MAC address like that, and
> > so dhcpd will not hand out that address.
>
>
> Which means they are blocked? Maybe then, there is really no spare IP?

Not blocked as such. As soon as you assign a  valid MAC address the IP 
address will be used. But until you do no thin client will receive that 
IP. The only dynamically assigned IP addresses are those you have listed 
in the stanza that Klaus mentioned in an earlier message.


  subnet 192.168.0.0 netmask 255.255.255.0 {
     # At least some thin clients will work out of the box, appearing as
     # ltsp200 to ltsp253.
     # We still recommend defining fixed mac adress to ip adress mappings,
     # cf. examples and explanations below.
     range 192.168.0.200 192.168.0.253 ;
  }


Unless you have changed the default settings, you will assign the 
adresses 192.168.0.200 to 192.168.0.253 to thin clients that have not 
been locked to an IP by listing its MAC address further down in the 
dhcpd.conf file. That's 54 potential addresses. If you have more than 
that number of thin clients and no fixed IPs, you will have a number of 
non functional thin clients.

The IP assigning process can be seen like this in order of priority:

1.
Assign a fixed IP address if MAC address is listed

2.
Assign an IP from the dynamic range if there are any leases (free IPs) 
available

3.
Do not assign any IP adress if there are no free leases


Remember that DHCP supplies a number of network related pieces of 
information, not only the IP. If there are no free leases, a thin client 
will not have an IP, no information on how to load its kernel, no root 
file system etc., etc. Then it's mooring material.


Of course, there could be other problems, like flaky network cards, 
switches that have features like spanning tree enabled that block DHCP, 
helpful fingers that switch off network booting in the BIOS. The list is 
 long.




--
Med vennlig hilsen
Ragnar Wisløff
-------------
Life is a reach. Then you gybe.