[OLPC Networking] Re: Ability to set the 802.11s TTL for outgoing packets

[Lennart Poettering]

On Tue, 10.10.06 12:12, Javier Cardona (javier at cozybit.com) wrote:

Hi!

> > Please note that I will never use large TTLs, i.e. those > 10. Hence,
> > a dirty solution could be to define some magic MAC addresses like
> > FF:FF:FF:FF:FF:FE which behave like a broadcast with TTL=1 and so
> > on. If you did this there wouldn't be a need to change the frame
> > format.
> 
> We will probably implement this as a sockopt, as you suggested
> earlier.

OK, that sounds nice. BTW, besides the ability to set the TTL for
outgoing packets I'd need the ability to query the TTL for incoming
packets, too.

> > in the range of 4-5. Is this true? What about the degree of the the
> > vertices (in the sense of graph theory, i.e. the number of connected
> > other vertices)? What is the maximum degree of vertices that is
> > expected in real-world networks? What are the parameters the Marvell
> > hardware has been designed for?
> 
> The number's I've heard are around 2000 nodes, and I have no info
> about the degree of the vertices.

Could you point me to a guy who might know this? 

Or does anyone else on this ML have any idea?

There is another variable in my simulation that I don't know much
about. That is maximum amount of traffic I am allowed generate on each
link for my service discovery. The Marvell chip is 54Mbit, right? I
read somewhere that OLPC will use it in 2MBit mode only, to save
power. Is that correct? Do yo know how much of these 2Mbit will
practically be left for application use? I am assuming that I may use
10% of that at max. Yes, I know that this value is probably not useful
without knowing how many machines are part of a the cell, but if i
know the maximum degree of the vertices I'll know that too.

> > One last thing: is cross-posting to the libertas and olpc-networking
> > mailing lists a good idea? I started this because I didn't know which
> > one to use, but perhaps we should move this thread to only one of
> > them. (probably libertas-dev?)
> 
> I don't know either ;)  So I'll just follow your lead for now...

Mhm, since nobody is complaining I'll keep cross-posting. ;-)

Thanks, 
        Lennart

-- 
Lennart Poettering; lennart [at] poettering [dot] net
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