Monday, September 12, 2011

More progress on the overlay mesh network

It is 5:58am and dawn is just beginning.

I have been up all night making the best of the need of an overnight sleep study for our son, which requires an adult to perform a specific function every 15 minutes throughout the night.

Programming in these little pieces feels a bit like the software development version of watching commercial television; just as you think you are about to witness something really interesting there is an interruption.

Nonetheless, I have made significant progress getting the overlay mesh to send and receive advertisements of a different kind; notices by one node that they can reach another node.

There are plenty of bugs that I know about, without even thinking about the ones that I don't know about, and also some code that is still plain old missing.  But even so, I have got the code forming a multi-hop mesh and keeping track of the routes to them.

I ran two nodes connected to two separate dummy networks, so that they couldn't see each other.  Then I connected an extra node in the middle that bridged the two networks, and after a short delay, viola, the nodes could all see each other.  The image shows the routing table from one of the nodes with only one network interface.

The 0000000* addresses in the neighbour table are clear evidence of some of those bugs I mentioned, as is the crazily large age field for one of those.

The FDB3BA1*, D64CEB4* and B167503* addresses are nodes that I had temporarily added to the mesh, and then removed again fairly recently, so the routes were (correctly) still hanging around with their link scores steadily dropping.

The important part is the route to D6850E3*, the node on the other network, for which the current route is via 30464E5*, which is the node bridging the two networks.  30464E5* was a node that I had previously bridging the networks just a short while earlier, and we can see the lingering route as it decays.

B167503* is the node currently bridging the link, and it's score is still climbing, and is about to overtake the recently removed node and become the route of choice.

So while I have a lot more work to do, the basic function of the mesh to discover multi-hop paths and switch routes based on appropriately calculated scores.

But right now, I am going to bed.

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