Cell Relay Archive

Cell Relay Retreat>List Archive>month:2000-Aug> msg00095



[Date Prev][Date Next][Thread Prev][Thread Next]  
  [Date Index][Thread Index][Author Index][Subject Index]

Re: EPD and PPD Simultaneously?

  • From: "Dominic Richens" <dominicr@nospamnortelnetworks.com>
  • Date: Fri, 25 Aug 2000 10:05:20 -0400
  • Organization: Nortel Networks



Daniel Horner <dnh@nortelnetworks.com> wrote in message
yvgg7l96k03d.fsf@nortelnetworks.com">news:yvgg7l96k03d.fsf@nortelnetworks.com...
> I'm wondering about the simultaneous application of EPD and PPD. Is
> there a benefit to using both of these discard policies at once? If I
> understand correctly, then PPD would still catch the tail-end of
> frames that "snuck past" the EPD threshold. Ie. the beginning of the
> AAL5 frame was transmitted when the queue was just under the EPD
> threshold.

PPD is there to discard all remaining cells in a frame, regardless of why a
cell was discarded. EPD only ever discards the first cell in a frame, if it
is received when the queue fill is above the EPD discard threshold (for
instance 80% of the queue size).  Hence PPD is needed to "clean up" after
EPD has discarded the first cell in a frame.