Recommendation on using the "gentle_" variant of RED
For the best behavior of RED in simulations and in implementations,
my advice would be to implement RED, and to run simulations,
with the "gentle_" parameter set to 1.
In the
"gentle_"
modification to RED in NS, the
packet-dropping probability varies from "max_p" to 1
as the average queue size varies
from "maxthresh" to twice "maxthresh". This option makes RED
much more robust to the setting of the parameters "maxthresh" and
"max_p", and was added to
NS on 6/12/99.
- Sally Floyd, March 3, 2000.
The "gentle_" parameter can be set in the NS simulator with the
following command:
Queue/RED set gentle_ true
For backwards-compatibility reasons, I have left the default value
of the gentle_ parameter in NS as false.
The "gentle_" variant of RED was implemented for an ATM switch,
and evaluated, in the following paper:
- V. Rosolen,
Bonaventure, O.,
and G. Leduc,
A RED discard strategy for ATM networks and its performance evaluation with TCP/IP traffic,
ACM Computer Communication Review, July 1999, and
Impact of cell discard strategies on TCP/IP in ATM UBR networks,
Proc. of the 6th Workshop on Performance Modelling and Evaluation of ATM
Networks (IFIP ATM'98) Ilkley, UK,
July 98.
Return to
[
Sally Floyd].
Last modified: March 2000