Re: Spin bit - semantics - rtt and loss

[Mikkel Fahnøe Jørgensen <[e-mail]>]

Just to summarize the square wave discussion:

It is possible to send many other patterns one bit at a time that deal with
both short and long range loss.
At some point I suggested emitting a 8 bit Gray code counter which is
emitted one bit at a time. Optionally repeated twice before changing in
order to better sync the signal. This repeats every 8 packets or every 16
packets.

It was designed for loss detection - not spin or RTT because that isn’t
encoded into signal. But it can be used to sync the instance of a separate
spin bit. This would use two bits.

Kind Regards,
Mikkel Fahnøe Jørgensen


On 23 March 2018 at 01.13.01, Lubashev, Igor (
ilubashe=[e-mail]) wrote:

Since we decided to put some work into spin bit, albeit in a separate
document from V1, here are some thoughts.

It is nice that spin bit can be used to estimate rtt. I am sure that it is
useful to many well-meaning people. It is not very useful to me, though.

When I debug network problems, they are much more likely to be about lost
packets. And I like to be able to know packet loss frequency and pattern
very accurately. (I am assuming an encrypted packet number, or the problem
would be trivial.)

I would prefer, if we have a spin bit, for it to spin not every rtt but
every, say, 10 packets that an endpoint sends. Client sends 10 packets with
0 and then 10 packets with 1, repeat. Sever does the same.

So maybe two spin bits -- one for rtt and one for loss? I would assume that
loss bit would assist in rtt estimation in case of loss.

Thoughts?

- Igor