On Thu, 12 Mar 2015, Narseo Vallina Rodriguez wrote:
Control-plane latency can affect more than you think and the control-plane dynamics can be very complex, including also promotions and demotions between UMTS channels to HS(D/U)PA(+) channels which also increase user-plane latency. The latter case affects more during long flows as a result of fairness policies implemented by the RNC as the number of HSPA channels are limited (each HSPA category has a defined number of channels using TDM).
Ok, I understand you're trying to get this right, however I don't see this as the most probable explanation for the use-case described.
Most of the time for this use-case, you'll see the HSPA channels get properly established after approximately 1 second, and they'll stay up until the transfer is done.
One RNC vendor I have fairly well knowledge of, would 400 packets of buffering in the GGSN->RNC->eNodeB->Handset direction. I don't know about the others.
With half a megabit/s of buffer drain, that means max 10 seconds of buffering if my calculations are correct. There can potentially be buffering in the GGSN/SGSN as well. This is if everything is working perfectly. If there are other problems, the drain rate might be slower than half a megabit/s and this might induce further latency.
-- Mikael Abrahamsson email: [email protected] _______________________________________________ Bloat mailing list [email protected] https://lists.bufferbloat.net/listinfo/bloat
