Hi!
I have a Traffic Control/QoS question about the W(RED - Random Early
Detection/Discard) curve implementation in the Traffic Control
environment.
Is this the right curve for RED - has it been tried to be implemented
in the Traffic Control environment?:
An Analytical RED Function Design Guaranteeing Stable System Behavior:
http://www.ist-mobydick.org/publications/aqm_iscc2003.pdf
Citat: "... The resulting function is non-linear and can be described
by a polynomial expression. The advantage of this function lies not
only in avoiding heavy oscillations but also in avoiding link
under-utilization at low loads. The applicability of the derived
function is independent of the load range, no parameters are to be
adjusted. Compared to the original linear drop function applicability
is extended by far.
For implementation the shape of the derived function can be
approximated with a normalized power function of the queue size. Our
example with realistic system parameters gives an approximation
function of the cubic of the queue size. The effort to implement the
approximated cubic function is not much higher compared to the linear
function..."
-
RED is mentioned here in the previous 2.4 kernel:
http://www.linuxguruz.com/iptables/howto/2.4routing-14.html
Quote: "...
In order to cope with transient congestion on links, backbone routers
will often implement large queues. Unfortunately, while these queues
are good for throughput, they can substantially increase latency and
cause TCP connections to behave very bursty during congestion.
...
RED statistically drops packets from flows before it reaches its hard
limit. This causes a congested backbone link to slow more gracefully,
and prevents retransmit synchronisation. This also helps TCP find its
''fair'' speed faster by allowing some packets to get dropped
sooner
keeping queue sizes low and latency under control. The probability of
a packet being dropped from a particular connection is proportional
to its bandwidth usage rather than the number of packets it transmits.
..."
thanks,
Glenn Moeller-Holst
