On Mar 23, 2007, at 9:11 AM, Avinash Sridharan wrote:
Hi Phil,
I agree that if you apply rate control to the client it would
limit the packet generation, but the reason I say the queueing
dynamics would override these affects is that rate control
algorithm assume all packets have the same service rate.
I don't understand what you mean by "all packets have the same
service rate." Fairness rarely operates in terms of packets; it
operates in terms of flows or node pairs. I'm not sure what fair
servicing on a packet basis means, as a packet is a singleton.
But since the queue is biased towards the forwarder the service
rate of a client packet will be less than the service rate of a
frowarded packet. Wouldn't the rate allocated to the client have to
take this into account ?
Again, I don't understand what you're asking. Are you asking about
how you would implement network fairness? Or are you commenting that
the current implementation of CtpForwardingEngineP does not have
commands/events which provide the information you would need to
implement fairness? This latter point is true -- you need to at least
see the queue depth. Rodrigo and Om are working on the implementation
so it can provide this information, in order to allow transport-level
fairness mechanisms (e.g., IFRC) to be built on top of a CTP topology.
I don't understand what you're trying to achieve that CTP won't let
you. I'll reiterate -- CTP has never claimed to provide network
fairness under high load. If anything, it focuses on the much more
common case in *low-power* sensornets of light load.
I agree with the point you made on the segregation of queues its
like applying a control algorithm on the queues itself. So would it
make sense to have a single queue for clients and forwarded packets
and serving them without bias (first come first serve) and allowing
rate controllers to control their rates ?
Sure -- isn't that what I said originally?
Phil
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