RE: [RPRWG] protection messages
Hello,
By accident I had a similar discussion about ATM OAM (I.610) with SDH people. The situation is similar and so is the solution :
-forget 50 ms restoration if you rely only on packet messages;
-use physical layer indications (LOS, AIS, ...)
regards
Jan Van Ruymbeke
Belgacom Advanced Networks & Systems / Network Innovation & Strategy / Strategy Architecture & Economics of Core network.
Koning Albert II laan 27, 1030 Brussel, Belgium
T: 32 2 202 45 80
GSM: 32 476 28 70 25
-----Original Message-----
From: Mike Takefman [mailto:tak@xxxxxxxxx]
Sent: 27 May 2002 21:27
To: Anoop Ghanwani
Cc: 'Daniel Zhu'; 'Necdet Uzun'; 'stds-802-17@xxxxxxxx'
Subject: Re: [RPRWG] protection messages
Only partially joking, many reliable protocols run over
ethernet networks.
I agree that we need to reliably have 50 ms reaction
times to faults. It is not clear to me that sending protection
information every 10ms in non fault conditions is a good
idea.
cheers,
mike
Anoop Ghanwani wrote:
>
> Mike,
>
> CSMA/CD is non-deterministic. Anyway, I assume you were
> joking (hence the chuckle?).
>
> -Anoop
>
> > -----Original Message-----
> > From: Mike Takefman [mailto:tak@xxxxxxxxx]
> > Sent: Friday, May 24, 2002 12:47 PM
> > To: Anoop Ghanwani
> > Cc: 'Daniel Zhu'; 'Necdet Uzun'; 'stds-802-17@xxxxxxxx'
> > Subject: Re: [RPRWG] protection messages
> >
> >
> > CSMA-CD comes to mind.
> >
> > he he he,
> >
> > mike
> >
> > 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
> > > > > >
> > > >
> >
> > --
> > Michael Takefman tak@xxxxxxxxx
> > Manager of Engineering, Cisco Systems
> > Chair IEEE 802.17 Stds WG
> > 2000 Innovation Dr, Ottawa, Canada, K2K 3E8
> > voice: 613-254-3399 fax: 613-254-4867
> >
--
Michael Takefman tak@xxxxxxxxx
Manager of Engineering, Cisco Systems
Chair IEEE 802.17 Stds WG
2000 Innovation Dr, Ottawa, Canada, K2K 3E8
voice: 613-254-3399 fax: 613-254-4867
**** DISCLAIMER ****
"This e-mail and any attachments thereto may contain information
which is confidential and/or protected by intellectual property
rights and are intended for the sole use of the recipient(s) named above.
Any use of the information contained herein (including, but not limited to,
total or partial reproduction, communication or distribution in any form)
by persons other than the designated recipient(s) is prohibited.
If you have received this e-mail in error, please notify the sender either
by telephone or by e-mail and delete the material from any computer.
Thank you for your cooperation."