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RE: BFD stability follow-up from IETF-91

Gregory Mirsky <gregory.mirsky@ericsson.com> Thu, 04 December 2014 15:49 UTC

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From: Gregory Mirsky <gregory.mirsky@ericsson.com>
To: Jeffrey Haas <jhaas@pfrc.org>, "Nobo Akiya (nobo)" <nobo@cisco.com>
Subject: RE: BFD stability follow-up from IETF-91
Thread-Topic: BFD stability follow-up from IETF-91
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Date: Thu, 04 Dec 2014 15:47:27 +0000
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References: <CO2PR0501MB823C222B7D62779F4DF58CDB3780@CO2PR0501MB823.namprd05.prod.outlook.com> <D0A647C1.28843%mmudigon@cisco.com> <CO2PR0501MB8234A1BDDFD008EE12C847AB3780@CO2PR0501MB823.namprd05.prod.outlook.com> <CECE764681BE964CBE1DFF78F3CDD3943F5AE38D@xmb-aln-x01.cisco.com> <CAG1kdogkUr2YyodeUPWOqea+2jqOkmdYnPywVHCw8j1+=9eM6A@mail.gmail.com> <CECE764681BE964CBE1DFF78F3CDD3943F5AE4AE@xmb-aln-x01.cisco.com> <20141204151708.GA9458@pfrc>
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Hi Jeff,
I can reference RFC 5357 here. The Appendix describes what is called TWAMP-Light mode with Stateless Reflector. About year and a half the Errata been accepted that describes Stateful Reflector, which supports measurement of one-way latency/jitter and packet loss metrics.

	Regards,
		Greg

-----Original Message-----
From: Rtg-bfd [mailto:rtg-bfd-bounces@ietf.org] On Behalf Of Jeffrey Haas
Sent: Thursday, December 04, 2014 7:17 AM
To: Nobo Akiya (nobo)
Cc: rtg-bfd@ietf.org
Subject: Re: BFD stability follow-up from IETF-91

On Thu, Dec 04, 2014 at 03:14:50PM +0000, Nobo Akiya (nobo) wrote:
> If what you say is the only requirement not met, one approach may be to pursue a non-standard-track document describing some suggested implementation techniques to locally store TX/RX timestamp.
> 
> Given that echo approach will be less accurate and given that we seem to be having difficulty converging, I thought I???ll throw out another idea.

I think my biggest concern is that the echo approach has bidirectional packet loss possibilities.  Async at least lets the receiver know about unidirectional packet loss.

Of course, if your goal is to notify the sender that their packets are being lost, you need a backchannel anyway.  I just don't know if we want that back channel to be bfd.

- Jeff

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