[OLSR-users] OLSR, routing, and extending 'virtual' networks.

John Clark (spam-protected)
Wed May 4 19:37:14 CEST 2005

I've gotten my wifi nodes stable enough to start looking at how I want
to use the 'mesh'.

At the moment, I'd like to know if other have the same sort of topology:

WIFI_10.10.0.XXX (perhaps a number of nodes)

The idea here is to 'extend' the network across the 
intervening wifi
mesh. Each node in the wifi mesh can have a copper connection, and hence 
allow 192.168.0.XXX nodes on the respective copper interfaces to appear to
be on the same 'virtual' copper network.

What I have observered is that 'linux' and OLSRD seems to do the right thing
to route to specific nodes which are running OLSRD, but getting non-OLSRD
manage nodes to work correctly seems problematic.

In the case of my NetBSD machine, it seems that it receives an 'arp' 
packet via
the mesh, but that packet is not correctly replied to by the 
'copper-to-mesh' connnecting

Also, since I'm using Madwifi for my wifi driver code, I don't really 
have WDS
working... I'm using the BSD of the linux driver which has the recently 
from Free/Net-BSD ad-hoc support. There is a WDS branch for the linux port
but I did not wish to try to merge those two branches...

I mention the WDS to indicate that I'm aware that 'arps' just don't 
happen naturally.

Anyway, have others tried, and what configurations were successfull in 
this sort
of network.

Also, I have observed some rather strange behavior in the OLSRD in a 
'just running'
mode, where it seems that it will build a large list of nodes, then 
'prune' them. This seems
to introduce a noticable lengthening of the response time for the ping 
packets I'm using just
to generate a modest amount of net traffic. Typically for a ping packet 
size of 512, I get a
1 ms response delay. However, when OLSRD is building then pruning 
things, I can see up to
20 ms (or more in my overnight test but that may have been due to other 
problems as well.).

Have others seen this sort of behavior as well.

John Clark

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