[K12OSN] DHCP and different LTSP distros

["Terrell Prudé Jr."]

Les Mikesell wrote:
> Terrell Prudé Jr. wrote:
>
>> Yes, but it depends on how your network is set up.  Because of how
>> DHCP works, your DHCP server would need an interface on each of the
>> LTSP client segments. 
>
> This isn't strictly true, but you do need DHCP relay support on
> routers connecting the segments.   If they are Cisco, that would be
> the 'ip helper-address' directive.  The DHCP server does need subnet
> configurations for each supported range (which can have separate boot
> and nfs servers you you like) but it doesn't have to be directly
> connected.
>

Strictly speaking, you're correct; DHCP relay would also work.  We must
remember, though, that the person coming behind the original installer
(quite possibly a schoolteacher) needs to be able to figure it out, too,
not just gearheads like you and me.  With LTSP, you likely won't have
Cisco routers at each LTSP segment; the LTSP server itself is doing that
L3 segmentation.  Correctly configuring DHCP relay agents on those LTSP
servers is a bit beyond *most* school tech admins.  Not all, but most. 
And because of that, in many cases (e. g. my district), the network
folks handle the network, and the school techs handle the
workstations/servers.

Therefore, it's typically a lot easier to get your network engineer, i.
e. someone like me, to pop some ports into a VLAN without questioning it
than it is to convince me to let someone stand up a second DHCP
*anything*.  The former, I'll say, "sure, no prob, give me two
minutes."  The latter...waitasec, we need to talk BIG TIME first.  This
is to avoid handing out, say, 192.168's on that 10.x.x.x network and
taking down half the school as a result.

--TP