Hi Rory,
I believe that in-band timestamps can certainly be a useful feature in NSH.
Major comments:
1. The draft currently does not clarify the use case. While the draft
describes how the timestamp is inserted into the NSH, I could not find a
description of how the timestamp is *used*, and what is the expected accuracy.
It is hard to assess whether the solution is adequate without understanding the
requirement.
2. Why does the draft mandate specific synchronization protocols (NTP,
Sync-E, PTP)? It seems that if you are defining an NSH timestamp TLV, you can
avoid limiting the solution, and leave the synchronization protocol out of
scope.
3. The timestamp formats are not clearly defined. Specifically, the term
"UTC format" is used throughout the document. I believe UTC defines a time
reference, not a timestamp format. Did you mean NTP Timestamp format / PTP
Timestamp format / RFC 3339 / other?
Other comments:
* Section 3.1:
You require both Synchronous Ethernet (2), and IEEE 1588 for frequency
distribution (3). These seem like two overlapping requirements. Why do you
require both? Perhap you meant that IEEE 1588 should be used for *time*
distribution?
* Could you explain why you require very accurate frequency
synchronization, but inaccurate time synchonization (section 3.1)?
* The format of the fields "UTC Reference", "Ingress Timestamp", and
"Egress Timestamp" is not clear.
* Section 3: the terms SCL and FTSN are used before they are defined.
SCL is not defined at all. I guess you mean Service Classifier, but this should
be specified.
* The terms "time stamp" and "timestamp" are used intermittently. I
believe "timestamp" is the most common form in IETF documents.
* "The FTSN also writes the UTC value into the header so the" - this
sentence is not clear at this point.
* The terms NTP and IEEE 1588 are used without a reference to the
relevant standards.
* Could you please clarify the following sentence:
"the UTC stamp is merely being used as a reference inserted into
the TSDB for performance monitoring. It is not a reference for the
timestamp itself."
Regards,
Tal.
From: sfc [mailto:[email protected]] On Behalf Of Browne, Rory
Sent: Friday, October 23, 2015 7:45 PM
To: [email protected]
Subject: [sfc] NSH Timestamp
Please see below a link to a draft on performance monitoring of service chains
using NSH
https://tools.ietf.org/html/draft-browne-ietf-sfc-nsh-timestamp-00
Comments welcome
BR Rory
--------------------------------------------------------------
Intel Shannon Limited
Registered in Ireland
Registered Office: Collinstown Industrial Park, Leixlip, County Kildare
Registered Number: 308263
Business address: Dromore House, East Park, Shannon, Co. Clare
This e-mail and any attachments may contain confidential material for the sole
use of the intended recipient(s). Any review or distribution by others is
strictly prohibited. If you are not the intended recipient, please contact the
sender and delete all copies.
_______________________________________________
TICTOC mailing list
[email protected]
https://www.ietf.org/mailman/listinfo/tictoc
