Re: [school-discuss] LTSP and school-provided networks on same physical infrastructure

[Daniel Howard <daniel@xxxxxxxxxxx>]

At 12:27 PM 6/30/2005, you wrote:
> Look into the capabilities of your switches.  If they support 802.1q VLAN
> trunking, then you can create a teacher's VLAN and a thin client VLAN.
> (VLAN means Virtual LAN, and is like having a separate subnet.  Packets
> sent out over a VLAN trunk have a special tag in front indicating the
> VLAN.)
>
> With proper configuration of your router (assuming it also supports VLANs),
> it can route between the subnets.  By the way, you could even use a Linux
> box as a router between the two VLANs.  Linux has VLAN support, I believe,
> or you could use two network cards and not even have to worry about VLANs.

The switches are probably 5-6 year old Cisco's (don't know the model number 
off hand), but that time frame would be right given the classroom PCs are 
running Win95/Win98.  I suspect they don't support 802.1q.  Probably also 
the routers.  Would every switch in the network physical path have to 
support 802.1q?  Would it be best to use switches from all the same 
manufacturer to guarantee compatibility? (we've had issues with wireless 
access cards from one manufacturer not working well with encryption-on with 
a wireless router from another manufacturer.)

Too bad we can't just put a third NIC in the classroom LTSP server and have 
it split the incoming school district traffic and LTSP traffic into two 
separate streams, and a similar 3-NIC Linux router box/LTSP server at the 
MDF that accepts both school district network feed and cable modem feed and 
outputs a single stream for the 24 port switches that feed the 
classrooms.  Maybe this could be a future feature of LTSP to make it 
possible for schools to use cost-effective data service backups.  Don't 
know what the cost is elsewhere, but it's going to cost us only $1150 a 
year to get 5 Mbps downstream/ 384 kbps upstream from our local cable 
provider, and that's 3-4 times the bandwidth (and probably more reliable) 
than we currently get from the school district.  We may even add a Vonage 
type VOIP system to the school in the future to allow classrooms to have 
audio conferences with experts and other classrooms worldwide at very low 
cost.  (We call Europe a lot from my home for family abroad, and my VOIP 
system has paid for itself many times over now.)

I even considered that if the school does not have coax cable to each class 
for delivery of educational TV programming to rooms (our state has a great 
satellite TV network), I'd use that as an excuse to run a single RG-6 or 
RG-11 coax trunk line past each room with RF taps,  RG-6 droplines to each 
classroom, and splitters in each room to a TV and cable modem, with a 
headend in the MDF using one of the lower cost pizza box cable modem 
termination systems (CMTS) that are available now.  (credit to Steve 
Jackson, friend of mine who worked at Arris for that idea several years 
ago.)  That way, we'd have a completely separate data network over the coax 
we could use for our own purposes.  For older schools with no existing 
wiring, it's a cheap way to wire the classrooms without the huge bundles of 
Cat5 that you see in the corners of the ceilings.

Daniel



Daniel Howard
President and CEO
Quadrock Communications, Inc
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