This is a good and important question. Even more so because Marek and I were having a initial discussion via VOIP about ideas and changes to the algorithm for the next generation mark 5 of the protocol algorithm. Our aim is (again) reduced computational and data overhead, faster convergence speed, a simplification of the protocol and added support for IPv6. This step will again call for a higher packet version number
How many of these goals can be reached without changing the packet format? I've implemented regenerating lost OGMs without changing the protocol to a degree it needs to bump the version number. Does removing the averaging of TQ from remote neighbors change the message format?
My question would be, does not changing the message format so that the version number can stay the same impose too high a penalty in terms of design restrictions?
Andrew