[B.A.T.M.A.N.] question regarding batmand convergence time

[B.A.T.M.A.N.] question regarding batmand convergence time

[Thomas Tiotto]

Good day,
I'm currently finishing writing my bachelor thesis whose topic is mesh
networks.  I have been running batmand and comparing it in performance
to olsrd; one metric I can't seem to be able to measure, though, is
network convergence time, i.e., the time it takes for a new node to be
discovered when connected and forgotten when disconnected from the
network.  This is due to the fact that batmand doesn't seem to display
updated information in the same way that olsrd does (with
DebugLevel=2).  I've tried looking at the routing tables but these also
aren't updated when a host disconnects and get purged after some time
has passed.
Is there any way I can get a real time view of the network to calculate
the time it takes for a host to be discovered/forgotten?

Thanks,

Thomas Tiotto
Università degli Studi di Milano

Re: [B.A.T.M.A.N.] question regarding batmand convergence time

[Sven Eckelmann]

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On Wednesday 22 June 2016 15:49:48 Thomas Tiotto wrote:
> Good day,
> I'm currently finishing writing my bachelor thesis whose topic is mesh
> networks.  I have been running batmand and comparing it in performance
> to olsrd; one metric I can't seem to be able to measure, though, is
> network convergence time, i.e., the time it takes for a new node to be
> discovered when connected and forgotten when disconnected from the
> network.

Hm, wouldn't it be more interesting to look at olsrd2, babeld, batman-adv,
802.11s, ... [1]? At least these are the "hip" things (without implying
that olsrd is old and grumpy - just not as ultra-hip as olsrd2 ;) ).

> This is due to the fact that batmand doesn't seem to display
> updated information in the same way that olsrd does (with
> DebugLevel=2).  I've tried looking at the routing tables but these also
> aren't updated when a host disconnects and get purged after some time
> has passed.
> Is there any way I can get a real time view of the network to calculate
> the time it takes for a host to be discovered/forgotten?

There is no "real time view" of the network. Just the TQ value and the
purge timeout. An originator doesn't say "goodbye" and thus the TQ value
usually just decreases when no OGM is received directly from them and
after a while the originator is purged.

New originators are discovered when new OGMs are received and will be used
the link is bidirectional and better than other links to specific
originators. So it is not really interesting when a new node is detected
but when a routes are updated (e.g. switched from a route via a
disappeared originator to a different originator). This behavior can be
changed by adjusting the originator interval. Mobile setups need a lower
originator interval and static setups can reduce the amount of overhead
by reducing the originator interval.

Maybe I forgot something in this very brief overview but I haven't looked
at the code of batmand since a while. Elektra, any comments?

But there are also other papers [2,3] which had a look at these things.
Maybe you are interested in checking them out.

Kind regards,
	Sven

[1] http://battlemesh.org/BattleMeshV9
[2] https://www.open-mesh.org/projects/open-mesh/wiki/Experience
[3] https://www.open-mesh.org/projects/open-mesh/wiki/New_papers

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