draft-ietf-ippm-checksum-trailer-04.txt		draft-ietf-ippm-checksum-trailer-05.txt
	Network Working Group T. Mizrahi		Network Working Group T. Mizrahi
	Internet Draft Marvell		Internet Draft Marvell
	Intended status: Experimental		Intended status: Experimental
	Expires: May 2016 November 9, 2015		Expires: May 2016 November 16, 2015
	UDP Checksum Complement in OWAMP and TWAMP		UDP Checksum Complement in OWAMP and TWAMP
	draft-ietf-ippm-checksum-trailer-04.txt		draft-ietf-ippm-checksum-trailer-05.txt
	Abstract		Abstract
	The One-Way Active Measurement Protocol (OWAMP) and the Two-Way		The One-Way Active Measurement Protocol (OWAMP) and the Two-Way
	Active Measurement Protocol (TWAMP) are used for performance		Active Measurement Protocol (TWAMP) are used for performance
	monitoring in IP networks. Delay measurement is performed in these		monitoring in IP networks. Delay measurement is performed in these
	protocols by using timestamped test packets. Some implementations use		protocols by using timestamped test packets. Some implementations use
	hardware-based timestamping engines that integrate the accurate		hardware-based timestamping engines that integrate the accurate
	transmission timestamp into every outgoing OWAMP/TWAMP test packet		transmission timestamp into every outgoing OWAMP/TWAMP test packet
	during transmission. Since these packets are transported over UDP,		during transmission. Since these packets are transported over UDP,
	skipping to change at page 1, line 47		skipping to change at page 1, line 47
	and may be updated, replaced, or obsoleted by other documents at any		and may be updated, replaced, or obsoleted by other documents at any
	time. It is inappropriate to use Internet-Drafts as reference		time. It is inappropriate to use Internet-Drafts as reference
	material or to cite them other than as "work in progress."		material or to cite them other than as "work in progress."
	The list of current Internet-Drafts can be accessed at		The list of current Internet-Drafts can be accessed at
	http://www.ietf.org/ietf/1id-abstracts.txt.		http://www.ietf.org/ietf/1id-abstracts.txt.
	The list of Internet-Draft Shadow Directories can be accessed at		The list of Internet-Draft Shadow Directories can be accessed at
	http://www.ietf.org/shadow.html.		http://www.ietf.org/shadow.html.
	This Internet-Draft will expire on May 9, 2016.		This Internet-Draft will expire on May 16, 2016.
	Copyright Notice		Copyright Notice
	Copyright (c) 2015 IETF Trust and the persons identified as the		Copyright (c) 2015 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
	This document is subject to BCP 78 and the IETF Trust's Legal		This document is subject to BCP 78 and the IETF Trust's Legal
	Provisions Relating to IETF Documents		Provisions Relating to IETF Documents
	(http://trustee.ietf.org/license-info) in effect on the date of		(http://trustee.ietf.org/license-info) in effect on the date of
	publication of this document. Please review these documents		publication of this document. Please review these documents
	skipping to change at page 3, line 17		skipping to change at page 3, line 17
	packets.		packets.
	The accuracy of delay measurements relies on the timestamping method		The accuracy of delay measurements relies on the timestamping method
	and its implementation. In order to facilitate accurate timestamping,		and its implementation. In order to facilitate accurate timestamping,
	an implementation can use a hardware based timestamping engine, as		an implementation can use a hardware based timestamping engine, as
	shown in Figure 1. In such cases, the OWAMP/TWMAP packets are sent		shown in Figure 1. In such cases, the OWAMP/TWMAP packets are sent
	and received by a software layer, whereas the timestamping engine		and received by a software layer, whereas the timestamping engine
	modifies every outgoing test packet by incorporating its accurate		modifies every outgoing test packet by incorporating its accurate
	transmission time into the <Timestamp> field in the packet.		transmission time into the <Timestamp> field in the packet.
	OWAMP/TWAMP-enabled Node		OWAMP/TWAMP-enabled Node
	+-------------------+		+-------------------+
	| |		| |
	| +-----------+ |		| +-----------+ |
	Software | |OWAMP/TWAMP| |		Software | |OWAMP/TWAMP| |
	| | protocol | |		| | protocol | |
	| +-----+-----+ |		| +-----+-----+ |
	| | |		| | | +---------------------+
	| +-----+-----+ |		| +-----+-----+ | / Intermediate entity |
	| | Accurate | |		| | Accurate | | / in charge of: |
	ASIC/FPGA | | Timestamp | |		ASIC/FPGA | | Timestamp | | /__ -Timestamping |
	| | engine | |		| | engine | | |-Updating checksum or|
	| +-----------+ |		| +-----------+ | | Checksum Complement |
	| | |		| | | +---------------------+
	+---------+---------+		+---------+---------+
	|		|
	|test packets		|test packets
	|		|
	___ v _		___ v _
	/ \_/ \__		/ \_/ \__
	/ \_		/ \_
	/ IP /		/ IP /
	\_ Network /		\_ Network /
	/ \		/ \
	\__/\_ ___/		\__/\_ ___/
	\_/		\_/
	Figure 1 Accurate Timestamping in OWAMP/TWAMP		Figure 1 Accurate Timestamping in OWAMP/TWAMP
	OWAMP/TWAMP test packets are transported over UDP. When the UDP		OWAMP/TWAMP test packets are transported over UDP. When the UDP
	payload is changed by an intermediate entity such as the timestamping		payload is changed by an intermediate entity such as the timestamping
	engine, the UDP Checksum field must be updated to reflect the new		engine, the UDP Checksum field must be updated to reflect the new
	payload. When using UDP over IPv4 ([UDP]), an intermediate entity		payload. When using UDP over IPv4 ([UDP]), an intermediate entity
	that cannot update the value of the UDP checksum has no choice except		that cannot update the value of the UDP checksum has no choice except
	to assign a value of zero to the checksum field, causing the receiver		to assign a value of zero to the checksum field, causing the receiver
	to ignore the checksum field and potentially accept corrupted		to ignore the checksum field and potentially accept corrupted
End of changes. 4 change blocks.
	29 lines changed or deleted		29 lines changed or added
This html diff was produced by rfcdiff 1.42. The latest version is available from http://tools.ietf.org/tools/rfcdiff/