RE: [RPRWG] RPR Perf: Single vs. Dual ring?]
I thought x is decided as 2. Is it not true ?
Regards,
Devendra Tripathi
VidyaWeb Inc.
Pune, India
Tel: +91-20-433-1362
> -----Original Message-----
> From: owner-stds-802-17@xxxxxxxx [mailto:owner-stds-802-17@xxxxxxxx]On
> Behalf Of Nader Vijeh
> Sent: Monday, April 30, 2001 11:37 AM
> To: 'Donghui Xie'; Stein Gjessing
> Cc: stds-802-17@xxxxxxxx
> Subject: RE: [RPRWG] RPR Perf: Single vs. Dual ring?]
>
>
>
> Whether flow control packets go backward, forward, both ways and/or
> hop-by-hop is a question that can be answered after we have agreed on the
> requirements.
>
> Does the group agree that the 802.17 MAC should be "able to support" n
> homogeneous rings (logical or physical)? Where n could be a
> number from 1 to
> x. x is fixed, such that interoperability is only required between MACs
> supporting x rings.
>
> Nader
>
> -----Original Message-----
> From: Donghui Xie [mailto:dxie@xxxxxxxxx]
> Sent: Monday, April 30, 2001 10:37 AM
> To: Stein Gjessing
> Cc: stds-802-17@xxxxxxxx
> Subject: Re: [RPRWG] RPR Perf: Single vs. Dual ring?]
>
>
>
> Hi Stein,
>
> Further with your answers, in dual rings, backward hop-by-hop control
> packet gives the fastest response time that is possible, since
> the control
> packet is allowed to go the shortest path to reach the node. As such, the
> flow control is less dependent on ring global size, and helps to minimize
> the interference with data flows. On the other hand, a broadcast control
> packet in single ring has to go the longest path, which not only
> makes the
> flow control be more sensitive to the ring size and distance, but also
> subjects the data flows and control flows over the whole ring to mutual
> interference.
>
> Donghui
>
> At 03:54 PM 4/28/2001 +0200, Stein Gjessing wrote:
>
> >Samian,
> >
> > > So, to clarify my understanding, we are using
> > > dual rings for flow control packets that propagate hop-by-hop
> upstream.
> >
> >Yes.
> >
> >I believe there already is a (close to) consensus on dual rings.
> >Remember that dual rings are also needed for protection.
> >
> >The flow control packets are, as you say, in a sense broadcasted.
> >But on a ring a broadcast needs to go hop by hop.
> >And upstream is the sensible way to send the packets, because
> >the node that bugs you is most probably closest upstream.
> >
> > > But, wouldn't it make the simulations easier if we could default to a
> more
> > > generic flow control scheme,
> >
> >I believe we have to simulate and understand the flow control schemes
> >down to the very details. Small changes in flow control can make big
> >changes in performance. Flow control is feedback, and if we don't get
> >it right we can get oscillations etc., that are typical for a badly
> >controlled feedback system.
> >
> >Stein
> >
> >
> >------Original Message-----
> >Return-path: <owner-stds-802-17@xxxxxxxx>
> >Envelope-to: steing@xxxxxxxxxx
> >Delivery-date: Sat, 28 Apr 2001 02:30:16 +0200
> >From: Samian Kaur <skaur@xxxxxxxxxxxxxx>
> >To: "'stds-802-17@xxxxxxxx'" <stds-802-17@xxxxxxxx>
> >Subject: Re: [RPRWG] RPR Perf: Single vs. Dual ring?
> >Date: Fri, 27 Apr 2001 16:43:50 -0700
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> >
> >
> >
> >Hi Stein,
> >
> >Thank you for the explanation. So, to clarify my understanding, we are
> using
> >dual rings for flow control packets that propagate hop-by-hop upstream.
> >
> >But, wouldn't it make the simulations easier if we could default
> to a more
> >generic flow control scheme, like maybe broadcasting the control packets.
> >This will be a more robust mechanism than hop-by-hop and also
> eliminate the
> >necessity of the second ring. The performance characteristics of this
> scheme
> >will also give us an insight into the performance tradeoff of
> this approach
> >for comparison.
> >
> >Do you think a scenario on these lines will be interesting?
> >
> >Thanks,
> >Samian
> >
> >- -----Original Message-----
> >From: Stein Gjessing [mailto:steing@xxxxxxxxxx]
> >Sent: Tuesday, April 24, 2001 11:41 PM
> >To: stds-802-17@xxxxxxxx
> >Subject: [RPRWG] RPR Perf: Single vs. Dual ring?
> >
> >
> >
> >Samian,
> >
> >I agree that a single ring will demonstrate the performance
> characteristics
> >of interest if we disregard flow control.
> >Analyzing performance with flow control (by sending flow control
> >packets upstream), the dual rings are of course necessary.
> >Then the interference between flow control packets and data packets
> >also become an interesting issue.
> >
> >(Also remember that packets are going at most half way around on
> one ring)
> >
> >Stein Gjessing
> >University of Oslo
> >
> >
> > >Hi Khaled,
> > >
> > >I know that the performance adhoc committee decided that the Phase I
> > >simulations should be done using dual rings. I am beginning to question
> if
> > >that is necessary. I think a single ring will demonstrate the
> performance
> > >characteristics of interest and save us a lot of run time in
> running the
> > >simulations and is much easier to analyze.
> > >
> > >Am I missing something?
> > >
> > >Samian Kaur
> > >Lantern Communications
>