Re: [RPRWG] protection messages
Anoop,
I don't think hop-by-hop relay of protection message is
any more reliable than broadcast. Packet could potentially
be lost at any of the hops. How often do you recommend
to re-broadcast protection message?
Daniel
Anoop Ghanwani wrote:
> 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
> > > >
> >