[MLB-WIRELESS] Revisiting OSPF

[Dan Flett]

Hi Mark.

If you’re running this little network yourself, then you may get away
with not using a routing protocol at all.  It depends on how you have
your network set up.  Are all the APs in the same (presumably large)
subnet?  If so, no routing is needed at all, but you will find the
performance of your network performance degraded by a lot of broadcast
traffic.  If you connect your subnet or subnets to another network, such
as the Melbourne Wireless network, you’ll probably want to install a
router in the subnet that connects to the “other” outside network.  By
running an OSPF service (or daemon) on your router you will be able to
advertise to the rest of the network that you exist and (presumably)
everyone on the rest of the network will be able to find your node(s).
Likewise, the OSPF service on your router will receive advertisements
from other OSPF routers so your router will know the direction (route)
to traverse to find other nodes and subnets.

If you do not have a router (or PC running a routing protocol), then you
will have to enter the routes manually (statically) so that your PC
(router) knows how to find the various parts of the rest of the network.
Routing tables can get quite large - you could end up with a table that
has directions to get to fifty or more subnets.  It would not be much
fun to keep that up to date.

If you do not have a PC or router at all then you are pretty much stuck
with running all your own APs (or AP clients) and your AP peers in the
same subnet.  You'll have to hope that your AP peers are doing the
routing for you.  If there are lots of nodes involved this can get quite
ugly - bandwidth will be used inefficiently - which is why the Melbourne
Wireless network favours routing between lots of small Ethernet subnets.

We are hoping that small, cheap wireless routers such as the Linksys
WRT54G are the answer to the problem of needing a chunky PC at each node
location.

Cheers,

Dan

-----Original Message-----
From: Mark Aitken [mailto:maitken at erggroup.com] On Behalf Of Mark Aitken
(Home)
Sent: Tuesday, 14 December 2004 14:24
To: Dan Flett
Cc: 'Melbourne Wireless Mailing List'; 'Nick Sibbing';
owner-melbwireless at wireless.org.au
Subject: RE: [MLB-WIRELESS] Revisiting OSPF


Hi Guys (& Gals?), 

How do these routing protocols assist those of us that just stick an
AP(s) (any AP) up on a pole and point a signal to another node(s)? 

Eg. 

If I where to have a series of AP's, at my location,  that joined others
together, however, for whatever reason, I did not have a host computer
controlling the routing, ie, just AP's interlinked.  A simple set up I
know, but may happen at a "well sited geographical data roundabout". 

Or is it nessecary to have a host PC doing all the smarts at these
strategic locations? 

Regards 

Mark 

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