[Cu-wireless] simple design proposal

David Young dyoung at ojctech.com
Fri Jul 26 16:14:50 CDT 2002

Here is a two-part proposal for an initial network that I think we can
build this summer. It will involve stations at Maiko's, Laura Huth's,
and Zach's because they are near to each other. All the stations will
run identical CD-ROMs, just like our previous plan, but the CD-ROM will
select its IP numbers differently, and it will not use any IP schemas
or any notion of a "pod," "uplink," or "customer" network.

We will use the network 10/8. At Zach's house is the Internet gateway,
which will NAT 10/8 to one or more numbers.

Stations will choose the host part of the IP number for an interface by
bitwise XORing the first 24 bits and the second 24 bits of the MAC number
on the interface to fill the host bits. If bitwise XORing the halves of a
MAC number do not produce different IP numbers, we will choose a better
hash than that, but collisions should be rare for most choices of hash
function, since I don't think we'll exceed a dozen stations any time soon.

Routing is by OSPF. Stations will treat their wireless interfaces as
point-to-multipoint interfaces to 10/8. Every station is in area 0.

Station hardware will consist of one Dell with Linksys WMP11 attached
with several feet of LMR400 to an omni antenna. You can get a 5.5 dBi
antenna with hardware for pole-mounting for only $50. You can buy an 8
dBi antenna for just $60. We already have a few poles and roof/chimney
mounts; we can buy more at Radio Shack for cheap.

How does this proposal sound?


David Young             OJC Technologies
dyoung at onthejob.net     Engineering from the Right Brain
                        Urbana, IL * (217) 278-3933

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