[B.A.T.M.A.N.] Enhancements for Unsolicited Neigh. Adv. / grat ARP Reply

["Linus Lüssing" <linus.luessing@web.de>]

Hi there,

Here's a little, rough patch to illustrate the idea we discussed a little
at the last Wireless Battle Mesh, that is forwarding the noisy IPv6
Unsolicited Neighbor Advertisements and gratuitous ARP Replies via unicast.

Currently these ugly unsol. NAs cause about 40% of ICMPv6 multicast
overhead in our networks here.

A little more detailed explanation with some pictures can be found here:

https://www.open-mesh.org/projects/batman-adv/wiki/Unicasting-unsolicited-neighbor-advertisements

In the few, simple scenarios with bridged-in hosts in VMs, the patch
seemed to do what it was supposed to do uppon roaming. Unsol. NAs did only
appear on the node the host roamed away from.

If I remember correctly, there were also some worries about how this
might work together with BLA-II. I gave it a little more thought and
had a look at the BLA-II source code, but couldn't find any issues.

The only BLA-II related non-ideal thing I could think of so far is
noted in the code of this patch at the according place (but I think
that might not matter much in practice).

Looking forward to hear about what you think about it, especially
conceptually.

Cheers, Linus