Clarify: get synchronized

Rémy Léone reporter

I suggest that we use the exchange of packets as a way to assess that two nodes are connected. If so we need to defined being synchronized as something along those lines while taking into account the channel hopping situation if it's enabled.

2017-05-19T09:06:11+00:00

Tengfei Chang

@sieben Able to communication could be used for verifying synchronization, 6N could send a data packet (any data packet) which require ACK to DR, if ACK is received from DR, then we say 6N is synchronized.

2017-05-19T10:09:05+00:00

Rémy Léone reporter

Maybe we could go on something a little bit more general to handle multi-hop scenarios.

Two 6TiSCH nodes A and B are syncronized if and only if they can successfully exchange information with acknowledgment.

We need to have a little sentence like this that is easy to remember :-)

2017-05-19T10:16:18+00:00

Rémy Léone reporter

@twatteyne Could you confirm that this definition is enough? Do you see something missing?

2017-05-23T10:11:50+00:00

Thomas Watteyne

I don't have any context on this, so hard to answer. Two nodes are synchronized when they can exchange DATA/ACK frame repeatedly. Given the guard time and the typical drift, I would say for at least 100s.

2017-05-23T14:15:13+00:00

Rémy Léone reporter

@twatteyne So would this sentence be ok as the definition of synchronicity:

Two 6TiSCH nodes are synchronized if and only if they can exchange successfully and repeatedly data and acknowledgment frame with each other during at least 100 seconds.

So that would mean at least 2 exchange of DATA/ACK frame with this phrasing. Would that be ok?

That would mean that each 6TiSCH test that requires nodes being synchronized would take at least 100 seconds. Of course, during a test session, tests can follow each other while the network keeps running. Therefore, we wouldn't have to wait for that delay for each test.