[Olsr-dev] OLSR on OLPC?

Henning Rogge (spam-protected)
Wed Jun 4 19:50:09 CEST 2008

On Wed, Jun 4, 2008 at 7:26 PM, C. Scott Ananian <(spam-protected)> wrote:
> The OLPC XO-1 has really nice and spiffy 802.11s hardware.
> Unfortunately, we're having some difficulty actually making it scale
> properly in dense or high-traffic scenarios.  I'm interested in:
>  a) consulting with you folks, who seem to have actual real-world
> experience deploying large scale mesh networks,
Olsrd runs on smaller hardware than the OLPC (233 Mhz RISC routers)
with nets with hundreds of nodes (600+) with 10-20% cpu power.

>  b) actually deploying olsrd as a fall-back mechanism on the XO --
> giving up the power benefits of running 802.11s autonomously in the
> wireless chip in exchange for perhaps better behavior in some
> scenarios,
I'm not sure if the 802.11s will really save power. You will have to test it.

>  c) finding out how well you are scaling these days: multiple hundreds of nodes?
see above ^^

>  d) discovering your experience with OLSR in dense networks: if I put
> 100 machines in a single room running olsrd, does the network break
> down due to discovery traffic?
If all nodes can see each other, you have a "one-hop" network... so
you will get only very few flooding of TCs.

Of course you have problems with collisions, but that's a problem with
all WLAN nets in high density situations.

>  e) do you separate data and control traffic?  If not, do you have
> problems with interference causing routing instabilities under high
> traffic conditions?
We don't do this. Yes, this can be a problem...

>  f) your thoughts on the OLSR extensions to the 802.11s standard: are
> they worth implementing, or did you need to tweak the standard OLSR
> protocol to make it work in real life?
Do you have a link where I could look at the 802.11s standard ? Olsrd
could easily be modified to work with MAC addresses instead of IPs I
think. But I don't see a real advantage (except that routing in kernel
space might be faster).

>  g) the media access protocol in standard 802.11 doesn't seem to scale
> much past 30-or-so nodes wanting to talk at the same time.  Have you
> run into this problem in dense deployments?
Hannes ? Aaron ?

>  h) there's some talk on the wiki about a new v2 rfc for olsr -- is
> there some place I could look at the work in progress?  what
> particular challenges does it aim to tackle?

see packetbb (new packet format), timetlv (time values for packetbb),
nhdp (neighborhood discovery protocol) and olsrv2.

we must support a completely new packet format and some changes in the
basic algorithms. It's planned for a later release of olsrd (first we
want to get ETT metrics ^^).

> Y'all seem to be doing great work, and I hope to start trying out
> olsrd on the XO builds, which at the least would give us a way to give
> non-XO-using developers a way to play with some of the mesh networking
> features of our software.
Sounds like a good idea :)


"Wo kämen wir hin, wenn alle sagten, wo kämem wir hin, und niemand
ginge, um einmal zu schauen, wohin man käme, wenn man ginge." (Kurt

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