Harry, You got it !
The interesting issue is that EF may or may not be TCP
traffic.
However, AF or BE traffic is
probably sporadic and bursty TCP
traffic.
TCP's congestion avoidance mechanism and the node to
node
signalling can interact to throtle the sources making BW
utilization
on
the ring bad.
I feel this begs simulation studies.
Raj:
Interesting traffic pattern....
If I understand your question,
the EF BW is reserved and leaked into the Ring
It appears as
reserved time slots; hence a periodic function?
The question is what is the congestion threshold and when to send
congestion notification. The time scale for congestion detection is
important. If buffers are used, then it is some buffer threshold.
Otherwise, is congestion
detected at cell level, burst level, call
level, or days etc.
There is one trade-off for fairness: stability versus maximize
BW utilization.
-If you response too fast going into congestion,
(reacting to small burst), you are susceptible to instability and you
BW efficiency may be reduced.
-If you response too slow, you will not be
fair, as some node may get starved.
-If you response too fast in
existing, you may not be fair again, and you oscillate.
-If you response
too slow in existing, you loose efficiency.
Regards,
Harry
Khaled Amer wrote:
Raj, Not sure I understand how you reached to the conclusion of 'the
traffic at any node would be a periodic function'. Can you shed some light on this?
Khaled Amer
President, AmerNet
Architecture Analysis and
Performance Modeling Specialists
Phone:
(949)552-1114
13711 Solitaire Way, Irvine, CA 92620
Fax:
(949)552-1116
e-mail: khaledamer@xxxxxxx
----- Original Message -----
Sent: Wednesday, August 16, 2000
9:36 AM
Subject: EF% vs. BCN
I would like to findout if anyone has giventhought to Explicit Forward (EF) traffic versus
BCN mechanismsused on buffer
insertion rings.Assume that x% of the BW is provisioned for
EF.As EF traffic into the ring it
will given highest priorityforwarding and hence to culminate in all EF
packets arriving together.
The BW consumed by EF traffic overtime can become a time
function. Example x(t) = sine
or square wave function of t with an amplitudeof x.As a
consequence available BW for the
rest of the traffic at any
node can become a periodic function. There could be interplaybetween this perdiodicity and the periodicity
of the
congestion notification
messages.Has anyone simulated this or have given thought
tothis?