Is the use model you envision for NTP to support hardware timestamping at the edge? In NTP, the addition of an extension field requires the presence of the MAC. This requires the dissemination and maintenance of keys as well as the defined MAC checking. How would this model work if the NTP packet did have the MAC? This extension field would be covered by the MAC and the authenticator would fail. Or do you expect this block would have the key info and update the MAC as well? And, how would it work if the MAC isn't there. Would the update not be used?
In PTP, there is a TC protocol function which necessitates the modification of the packet. In NTP, as it is defined as a UDP protocol, there is not as clear a path to how lower stack layers modify the PDUs. If you define this simply at the edge, I'm not sure how much value this additional UDP checksum update adds? Is there a model you have in mind? From: [email protected] [mailto:[email protected]] On Behalf Of Tal Mizrahi Sent: Monday, July 04, 2011 5:01 AM To: [email protected]; [email protected] Subject: [TICTOC] [ntpwg] New draft: draft-mizrahi-tictoc-checksum-trailer-00 Hi, I have posted a new draft that discusses Checksum updates in time synchronization protocols. http://tools.ietf.org/html/draft-mizrahi-tictoc-checksum-trailer-00 Comments will be welcome. Thanks. Tal.
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