RPL client node version bogus incrementation

[nashif]

Reported by Tomasz Bursztyka:

Setup:

• Sparrow Border Router (BR), being the RPL root node
• a zephyr acting as RPL client node

test:

• Start the BR
• Start the client
• once the client has joined the network, restart the BR.

At this point, from wireshark, we can see the RPL version number being incremented every now and then by the client, though it should not do that, and the BR doing it as well as it tries to stay the root node. At this point it will loop forever, battling for fixing the version number.

Issue: Looks like once the BR drops, the client node has kept wrong info about its own rank, and once the BR is up again, it thinks its rank is higher than BR's and thus it is the root node.

Will produce logs later on.

(Imported from Jira ZEP-2277)

[nashif]

by Andrei Laperie:

Marked as in-progress since investigation is still ongoing.

[nashif]

by Ravi kumar Veeramally:

Rank calculation was wrong, fix already merged to upstream a month ago. I have to investigate thoroughly version increment with different topologies of mesh network.