[rmcat] Updates for Test Case 5.5 and 5.6 in draft-ietf-rmcat-eval-test

["Xiaoqing Zhu (xiaoqzhu)" <[e-mail]>]

Hi all,

We are about to update the test case draft to keep it alive by September 11, 2015. And, as co-author, I would like to poll the mailing list regarding two proposed changes for Test Case 5.5 and 5.6.

  *   Test Case 5.5 (RTT Fairness):  currently all flows start gradually, and that may lead to late-coming flows settling at higher rates if they rely on queuing delay measurements.  Since the intention of this test case is to measure fairness w.r.t RTT, would it make more sense to start all flows at the same time, or roughly the same time (e.g., random start within 5 seconds) to avoid flow synchronization effects?  Notice that if any candidate scheme has an issue with late-comer advantage, that should have already been exposed by Test Case 5.4.
  *   Test Case 5.6 (RMCAT vs. Long TCP): currently 3 bottleneck queue sizes are specified:  20ms, 300ms, 1000ms. Given that most AQM schemes (CoDel and PIE) are striving to contain queuing delay with a target of 20ms, while allowing for a larger physical queue size to accommodate instantaneous bursts, a value of 20m for a drop-tail queue depth seems rather out of place.  Should we simply remove the value of 20ms for now?   If we want testers to play with a lower queue depth, we may start with 100ms of queuing, which corresponds to the bandwidth-delay product along that path (50ms propagation each direction).  On a related note: the queue depth for QoS aware in the eval-criteria draft (Sec 5.3) is specified as 70ms. Just wondering how that number came about?

Basically, I would like to get a sense of how much debate is needed regarding possible revisions of the above two points. So as to decide whether we should make changes to the draft now, or defer till after more discussions on the list or in IETF-94.

Thanks,
Xiaoqing