Re: [B.A.T.M.A.N.] problem starting batmand (v799)

Axel Neumann
2007-11-20T11:32:11Z

Hello,

On Dienstag 20 November 2007, rene wrote:
> Hi,
>
> Axel Neumann wrote:
> > Hi,
> >
> > On Dienstag 20 November 2007, rene wrote:
> >> Hi,
> >>
> >> starting batmand, the daemon sometimes doesn't seem to recognize the
> >> network the right way.
> >>
> >>
> >> root@25:~# killall batmand
> >> root@25:~# batmand eth1:1 vlan0:1
> >> Using interface eth1:1 with address 192.168.42.25 and broadcast address
> >> 192.168.43.255
> >> Using interface vlan0:1 with address 192.168.42.25 and broadcast address
> >> 192.168.43.255
> >>
> >> -------------------------------------------
> >> on the other node:
> >> root@25:~# killall batmand
> >> root@25:~# batmand eth1:1 vlan0:1
> >> Using interface eth1:1 with address 192.168.42.25 and broadcast address
> >> 192.168.43.255
> >> Using interface vlan0:1 with address 192.168.42.25 and broadcast address
> >> 192.168.43.255
> >> root@25:~#
> >
> > What is definitively not correct is that your capture indicates 4 times
> > the same IP address (192.168.42.25) on 4 different interfaces.
>
> This is two times the same node, first time it recognizes the broadcast
> the right way, second time not.
of course, ive been somwhow distracted by "the other node"
>
> > There MUST be a different IP address for each BATMAN interface in the
> > network (also if a single BATMAN node has more than one interface).
>
> Is this implemented like this (where?)?
Yes it is implemented/designed like this. It operates on layer three and
above. IP addresses are used to differentiate between different links to the
same neighbors. For example two nodes A and B, each with two wireless
interfaces 1 and 2. All interfaces operating in the same channel, bssid, ...
How could node A differentiate between the link A1<->B1 and A1<->B2 if it is
not aware of any MAC addresses. But even if it is aware of MAC addresses. How
could it set up the routing table to ensure that a packet to a distant node C
should be routed via B1 (and NOT via B2)?

> Can't work BATMAN with the
> interfaces (or can't we change it to work this way)
i guess its not that easy but if you are familiar with protocol design and c
coding go ahead...
Or you take a look on batman-advanced, but thats another story :-)
> , it would make the
> whole configuration much easier to assign to every node only one single
> IP address (or two, one for olsr and ne for BATMAN)? We are doing this
> with olsr and this really makes the network-structure much cleaner -
> every node has one IP.

Actually, I did not even know that this is possible - is such a configuration
proposed somewhere. I can imagine that this somehow works but how shure are
you that this does not introduce any negative side effects?

ciao,
axel

>
> Is the described problem with the misconfigured broadcast related to the
> 'same IP on different interfaces' issue?
>
> regards,
> Rene
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