Re: [B.A.T.M.A.N.] dynamic gateway / hna / services

Axel Neumann
2007-08-04T09:43:36Z

Hello!

On Freitag 03 August 2007, Freifunk Dresden wrote:
> Hello,
> I didn't get the email for this request, so the mailling list thread
> my be brocken.
strange, anybody else experienced problems?

[...]

> > > I'm currently checking how the HNA is working, but until now I can not
[...]
> I have checked out the rv491 and it seems working. In my test environment I
> use a laptop (i386) and two wrt54gl. The wrt shows at "-d3" that the
> announced HNA is added/deleted every 1-5 seconds. The wrt that has a
> greater distance (5meter 2 walls between) adds and deletes the HNA in a
> highe frequency than the
> wrt that is about 50cm away.
> I think that HNA should not be deleted to fast because someone that is
> using this "bad" connection will get often error messages during
> surfing that the rout e is not found. It would be better if just the
> connection slow because of transmistion errors.

that should not be the case! You say even with the stable connection to your
near-by WRT that the HNA is added/deleted every 1 - 5 SECONDS ! And even more
often at the distant WRT (so added/deleted every SECOND ?).
Can you describe the setup and parametrization in more detail?

> > [...]
> >
> > > Another Idea of the "-m" is to differenciate this parameter to -M
> > > <"message"> and -m <send-script>. by calling batmand -c -m send-script,
> > > batmand can setup stdin/stdou as binary file handle and fill a user-OGM
> > > with binary data that is then send.
> >
> > Even if such message-flooding ist not implemented I just thought of
> > whether there exist some standardized formats to announce such
> > services (maybe the community network markup language CNML idea) ?
> > ciao, axel
>
> I have looked through the code and have seen that the HNA is simply
> appended to
> the end of a message. if we want to send other information a TLV structure
> is needed (Tag-length-value). Batmand can ignore unknown Tags and is
> still working in the network. At moment the whole network needs an
> update at same time, because old batmand will interpret any data as HNA.
> I hope I'm not wrong :)

Do you really think of a human-readable ascii string that you want to flood
with an arbitrary length over the mesh with content like: "Hello take a cool
beer and see my fancy cool movie torrent-server at 105.10.bla.bub". Iam not
against such communication but...

default OGM size: 10 bytes
OGM + HNA size: 15 bytes
OGM + example-TLV-ascii message: 95 bytes

... I am a bit scared about the amount of data which would be flooded over the
mesh (at every originator interval) with no means for stopping the sources.

Therefore i asked if anybody knows a decent forman for describing such
services (preferably in a short and machine readable notation).
Perhaps another approach is to just have a kind of key-to-service list
(similar to /etc/services with a 16bit key) just roughly indicating the type
of offered service together with another port/ip where further information
(of arbitrary length) about the indicated service can be retrieved.
This would also allow to outsource part of the service-discovery to another
daemon.

greetings,
axel