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

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

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 Howard
President and CEO
Quadrock Communications, Inc
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