RE: [RPRWG] protection messages
Daniel,
The exponential backoff is what I don't like. I would
rather see it sent at a steady rate, or just transmitted
reliably so that there is no constant refresh.
Are there any protocols that use a similar exponential
backoff to guarantee timely delivery?
-Anoop
> -----Original Message-----
> From: Daniel Zhu [mailto:dzhu@xxxxxxxxx]
> Sent: Friday, May 24, 2002 11:19 AM
> To: Anoop Ghanwani
> Cc: 'Necdet Uzun'; 'stds-802-17@xxxxxxxx'
> Subject: Re: [RPRWG] protection messages
>
>
> Anoop,
>
> I believe, in the current RPR draft, protection message will
> be broadcast periodically every 1 second in steady state.
> During period of changes, protection message will be sent
> much more frequently with a back off scheme up to 1 second.
>
> Is there something missing here?
>
> Daniel
>
> Anoop Ghanwani wrote:
>
> > Necdet,
> >
> > Thanks for pointing this out. Per the current draft,
> > Type B's aren't sent that often (1/10-th the rate of
> > Type A's) and so it's possible that they can be
> > sourced in software.
> >
> > Anyway, let's assume for now that we absolutely had
> > to keep protection and fairness separate. How would
> > you recommend that we address the issue of timely
> > delivery of the protection notification message?
> >
> > I see only 2 possibilties:
> >
> > - Periodic link status broadcasts (regardless of whether
> > the link is up or not).
> >
> > - Hop-by-hop reliable broadcast when the link status
> > changes.
> >
> > I'm OK with either. Can you think of any other ways
> > to do this?
> >
> > -Anoop
> >
> > > -----Original Message-----
> > > From: Necdet Uzun [mailto:nuzun@xxxxxxxxx]
> > > Sent: Thursday, May 23, 2002 7:13 PM
> > > To: Anoop Ghanwani
> > > Cc: 'stds-802-17@xxxxxxxx'
> > > Subject: Re: [RPRWG] protection messages
> > >
> > >
> > > Anoop,
> > >
> > > Type B fairness message is generated by Fairness Control Unit (in
> > > hardware) and sent to client, whereas protection messages are
> > > generated
> > > MAC control unit (which is implemented in software) and
> multicast to
> > > other MACs' control units. Combining them is the worst
> that can happen
> > > (HW vs SW, microsecond time frame vs millisecond time frame etc.)
> > >
> > > Thanks.
> > >
> > > Necdet
> > >
> > > Anoop Ghanwani wrote:
> > >
> > > > I had a comment that expressed concern about the delivery
> > > > of protection notification messages.
> > > >
> > > > The way things are defined in D0.2, the messages are
> > > > neither reliable nor periodic. There are no
> > > > acknowledgments, so we are never sure that all nodes
> > > > have seen the protection notification message.
> > > > Sending special protection messages periodically
> > > > increases the overhead (but even that is not specified).
> > > > Why can't we piggyback the protection notification
> > > > onto Type B fairness messages since they are required
> > > > to be sent frequently in any case (typically more
> > > > frequently than 1 msec)?
> > > >
> > > > The ad hoc's response to my comment says that Type B's
> > > > are optional. This is not true. Sending of both Type A
> > > > and Type B messages is mandatory per D0.2 and there have
> > > > been no comments to change that behavior.
> > > >
> > > > -Anoop
> > > > --
> > > > Anoop Ghanwani - Lantern Communications - 408-521-6707
> > >
>