rfc9769v2.txt		rfc9769.txt
	Internet Engineering Task Force (IETF) M. Lichvar		Internet Engineering Task Force (IETF) M. Lichvar
	Request for Comments: 9769 Red Hat		Request for Comments: 9769 Red Hat
	Updates: 5905 A. Malhotra		Updates: 5905 A. Malhotra
	Category: Standards Track Boston University		Category: Standards Track Boston University
	ISSN: 2070-1721 April 2025		ISSN: 2070-1721 May 2025
	NTP Interleaved Modes		NTP Interleaved Modes
	Abstract		Abstract
	This document specifies interleaved modes for the Network Time		This document specifies interleaved modes for the Network Time
	Protocol (NTP). These new modes improve the accuracy of time		Protocol (NTP). These new modes improve the accuracy of time
	synchronization by enabling the use of more accurate transmit		synchronization by enabling the use of more accurate transmit
	timestamps that are available only after the transmission of NTP		timestamps that are available only after the transmission of NTP
	messages. These enhancements are intended to improve timekeeping in		messages. These enhancements are intended to improve timekeeping in
	skipping to change at line 128 ¶		skipping to change at line 128 ¶
	This document describes an interleaved client/server mode,		This document describes an interleaved client/server mode,
	interleaved symmetric mode, and interleaved broadcast mode. In these		interleaved symmetric mode, and interleaved broadcast mode. In these
	modes, the server sends a packet that contains a transmit timestamp		modes, the server sends a packet that contains a transmit timestamp
	corresponding to the transmission of the previous packet that was		corresponding to the transmission of the previous packet that was
	sent to the client or peer. This transmit timestamp can be captured		sent to the client or peer. This transmit timestamp can be captured
	in any software or hardware component involved in the transmission of		in any software or hardware component involved in the transmission of
	the packet. Both servers and clients/peers are required to keep some		the packet. Both servers and clients/peers are required to keep some
	state specific to the interleaved mode.		state specific to the interleaved mode.
	An NTPv4 implementation that supports the client/server and		An NTPv4 implementation that supports the interleaved client/server
	interleaved broadcast modes interoperates with NTPv4 implementations		and interleaved broadcast modes interoperates with NTPv4
	without this capability. A peer using the interleaved symmetric mode		implementations without this capability. A peer using the
	does not fully interoperate with a peer that does not support it.		interleaved symmetric mode does not fully interoperate with a peer
	The mode needs to be configured specifically for each symmetric		that does not support it. The mode needs to be configured
	association.		specifically for each symmetric association.
	The interleaved modes do not change the NTP packet header format and		The interleaved modes do not change the NTP packet header format and
	do not use new extension fields. The negotiation is implicit. The		do not use new extension fields. The negotiation is implicit. The
	protocol is extended with new values that can be assigned to the		protocol is extended with new values that can be assigned to the
	origin and transmit timestamps. Servers and peers check the origin		origin and transmit timestamps. Servers and peers check the origin
	timestamp to detect requests conforming to the interleaved mode. A		timestamp to detect requests conforming to the interleaved mode. A
	response can only be valid in one mode. If a client or peer that		response can only be valid in one mode. If a client or peer that
	does not support the interleaved mode received a response conforming		does not support the interleaved mode received a response conforming
	to the interleaved mode, it would be rejected as bogus.		to the interleaved mode, it would be rejected as bogus.
End of changes. 2 change blocks.
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