[Codel] CoDel and GPRS in osmo-pcu

Kathleen Nichols nichols at pollere.com
Mon Dec 21 14:44:02 EST 2015


On 12/21/15 12:58 AM, Jacob Erlbeck wrote:
> Hello,
> just for your information:
> we have added active queue management based on CoDel to the osmo-pcu
> project (https://openbsc.osmocom.org/trac/wiki/osmo-pcu), which is an
> open source software based GPRS-only PCU implementation.
> The implementation is based on
> http://queue.acm.org/appendices/codel.html but is deployed as a time
> stamp based automaton. It is being applied independently per mobile
> station (phone) in downlink direction only.
> The goal was to have PCU based AQM as a last resort if BSSGP flow
> control is not sufficient. Since the IP packets are eventually split and
> encapsulated within LLC frames which are generally encrypted, the PCU is
> not an optimal place to do AQM. Nevertheless it improves the TCP
> "experience" and downlink ping latencies under load significantly.
> Kind regards
> Jacob

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