Feature #5437


brainstorm about making protocol even more efficient

Added by laforge about 2 years ago. Updated about 2 years ago.

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Right now in the PoC protocol of laforge/e1oip we still send something in the order of 8000/(32..40) = 200 .. 250 UDP packets per second even if there are no active timeslots at all.

This really only serves the following purpose:
  • theoretical ability for a receiver without GPS-DO (client) to re-construct timing based on the averaged recorvered packet timing
  • ability of receiver to quickly detect lost frames (network problems or the like)
  • keep-alive of any NAT mapping/bindings

But at least in the current icE1usb hardware with GPS-DO, timing recovery is not really needed. And whether or not it is required to detect outages as fast as 50ms after they happen is somewhat disputable.

So why not introduce a mode in which we suppress idle packet transmission even further? For example, if we went down into a "1 PPS" mode during periods of quiescence, we would drastically reduce the network load / bandwith use, while still providing the peer to determine the alive-status of the network connection. Basically something like DTX (discontinuous transmission) in GSM, where transmissions are reduced to the SACCH only, if no [voice] activity is detected.

Any kind of alarms (TS0 processing) could of course trigger instantaneous transmission of packets.

Am I missing something here?

Actions #1

Updated by laforge about 2 years ago

The current 16bit timestamp covers more than 8s, so the 1PPS would still allow proper counting of frames and start to re-insert them at the right frame number.

In order to cover longer (accidential, not intentional) outages without loosing alignment, we could introduce an optional IE containing a longer (32bit == 149 hours) sequence number which could be added by the sender e.g. every time the 16bit number wraps. But the question is whether or not that matters at all...


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