< draft-ietf-bier-path-mtu-discovery-01.txt		draft-ietf-bier-path-mtu-discovery-02.txt >
	BIER Working Group G. Mirsky		BIER Working Group G. Mirsky
	Internet-Draft ZTE Corp.		Internet-Draft ZTE Corp.
	Intended status: Standards Track T. Przygienda		Intended status: Standards Track T. Przygienda
	Expires: July 21, 2017 Juniper Networks		Expires: January 17, 2018 Juniper Networks
	A. Dolganow		A. Dolganow
	Nokia		Nokia
	January 17, 2017		July 16, 2017
	Path Maximum Transmission Unit Discovery (PMTUD) for Bit Index Explicit		Path Maximum Transmission Unit Discovery (PMTUD) for Bit Index Explicit
	Replication (BIER) Layer		Replication (BIER) Layer
	draft-ietf-bier-path-mtu-discovery-01		draft-ietf-bier-path-mtu-discovery-02
	Abstract		Abstract
	This document describes Path Maximum Transmission Unit Discovery		This document describes Path Maximum Transmission Unit Discovery
	(PMTUD) in Bit Indexed Explicit Replication (BIER) layer.		(PMTUD) in Bit Indexed Explicit Replication (BIER) layer.
	Status of This Memo		Status of This Memo
	This Internet-Draft is submitted in full conformance with the		This Internet-Draft is submitted in full conformance with the
	provisions of BCP 78 and BCP 79.		provisions of BCP 78 and BCP 79.
	skipping to change at page 1, line 35 ¶		skipping to change at page 1, line 35 ¶
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF). Note that other groups may also distribute		Task Force (IETF). Note that other groups may also distribute
	working documents as Internet-Drafts. The list of current Internet-		working documents as Internet-Drafts. The list of current Internet-
	Drafts is at http://datatracker.ietf.org/drafts/current/.		Drafts is at http://datatracker.ietf.org/drafts/current/.
	Internet-Drafts are draft documents valid for a maximum of six months		Internet-Drafts are draft documents valid for a maximum of six months
	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."
	This Internet-Draft will expire on July 21, 2017.		This Internet-Draft will expire on January 17, 2018.
	Copyright Notice		Copyright Notice
	Copyright (c) 2017 IETF Trust and the persons identified as the		Copyright (c) 2017 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 31 ¶		skipping to change at page 3, line 31 ¶
	MTU: Maximum Transmission Unit		MTU: Maximum Transmission Unit
	OAM: Operations, Administration and Maintenance		OAM: Operations, Administration and Maintenance
	PMTUD: Path MTU Discovery		PMTUD: Path MTU Discovery
	1.1.2. Requirements Language		1.1.2. Requirements Language
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and		"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
	"OPTIONAL" in this document are to be interpreted as described in		"OPTIONAL" in this document are to be interpreted as described in BCP
	[RFC2119].		14 [RFC2119] [RFC8174] when, and only when, they appear in all
			capitals, as shown here.
	2. Problem Statement		2. Problem Statement
	[I-D.ietf-bier-oam-requirements] sets forth the requirement to define		[I-D.ietf-bier-oam-requirements] sets forth the requirement to define
	PMTUD protocol for BIER domain. This document describes the		PMTUD protocol for BIER domain. This document describes the
	extension to [I-D.ietf-bier-ping] for use in BIER PMTUD solution.		extension to [I-D.ietf-bier-ping] for use in BIER PMTUD solution.
	Current PMTUD mechanisms ([RFC1191], [RFC1981], and [RFC4821]) are		Current PMTUD mechanisms ([RFC1191], [RFC8201], and [RFC4821]) are
	primarily targeted to work on point-to-point, i.e. unicast paths.		primarily targeted to work on point-to-point, i.e. unicast paths.
	These mechanisms use packet fragmentation control by disabling		These mechanisms use packet fragmentation control by disabling
	fragmentation of the probe packet. As a result, a transient node		fragmentation of the probe packet. As a result, a transient node
	that cannot forward a probe packet that is bigger than its link MTU		that cannot forward a probe packet that is bigger than its link MTU
	sends to the packet source an error notification, otherwise the		sends to the packet source an error notification, otherwise the
	packet destination may respond with a positive acknowledgement.		packet destination may respond with a positive acknowledgement.
	Thus, possibly through a series of iterations, varying the size of		Thus, possibly through a series of iterations, varying the size of
	the probe packet, the packet source discovers the PMTU of the		the probe packet, the packet source discovers the PMTU of the
	particular path.		particular path.
	skipping to change at page 6, line 6 ¶		skipping to change at page 6, line 8 ¶
	its BMS and set size of the next probe as min(MTU, MTU')		its BMS and set size of the next probe as min(MTU, MTU')
	If upon expiration of the Echo Request timer BFIR didn't receive any		If upon expiration of the Echo Request timer BFIR didn't receive any
	Echo Replies, then the size of the probe SHOULD be decreased. There		Echo Replies, then the size of the probe SHOULD be decreased. There
	are scenarios when an implementation of the PMTUD would not decrease		are scenarios when an implementation of the PMTUD would not decrease
	the size of the probe. For example, if upon expiration of the Echo		the size of the probe. For example, if upon expiration of the Echo
	Request timer BFIR didn't receive any Echo Reply, then BFIR MAY		Request timer BFIR didn't receive any Echo Reply, then BFIR MAY
	continue to retransmit the probe using the initial size and MAY apply		continue to retransmit the probe using the initial size and MAY apply
	probe delay retransmission procedures. The algorithm used to delay		probe delay retransmission procedures. The algorithm used to delay
	retransmission procedures on BFIR is outside the scope of this		retransmission procedures on BFIR is outside the scope of this
	specification. The BFIR sends probes using BMS and locally defiined		specification. The BFIR sends probes using BMS and locally defined
	retransmission procedures until either the bit string is clear, i.e.		retransmission procedures until either the bit string is clear, i.e.
	contains no set bits, or until the BFIR retransmission procedure		contains no set bits, or until the BFIR retransmission procedure
	terminates and PMTU discovery is declared unsuccessful. In case of		terminates and PMTU discovery is declared unsuccessful. In case of
	convergence of the procedure, the size of the last probe indicates		convergence of the procedure, the size of the last probe indicates
	the PMTU size that can be used for all BFERs in the initial BMS		the PMTU size that can be used for all BFERs in the initial BMS
	without incurring fragmentation.		without incurring fragmentation.
	Thus we conclude that in order to comply with the requirement in		Thus we conclude that in order to comply with the requirement in
	[I-D.ietf-bier-oam-requirements]:		[I-D.ietf-bier-oam-requirements]:
	skipping to change at page 7, line 32 ¶		skipping to change at page 7, line 32 ¶
	6. Acknowledgement		6. Acknowledgement
	Authors greatly appreciate thorough review and the most detailed		Authors greatly appreciate thorough review and the most detailed
	comments by Eric Gray.		comments by Eric Gray.
	7. References		7. References
	7.1. Normative References		7.1. Normative References
	[I-D.ietf-bier-architecture]
	Wijnands, I., Rosen, E., Dolganow, A., Przygienda, T., and
	S. Aldrin, "Multicast using Bit Index Explicit
	Replication", draft-ietf-bier-architecture-05 (work in
	progress), October 2016.
	[I-D.ietf-bier-ping]		[I-D.ietf-bier-ping]
	Kumar, N., Pignataro, C., Akiya, N., Zheng, L., Chen, M.,		Kumar, N., Pignataro, C., Akiya, N., Zheng, L., Chen, M.,
	and G. Mirsky, "BIER Ping and Trace", draft-ietf-bier-		and G. Mirsky, "BIER Ping and Trace", draft-ietf-bier-
	ping-00 (work in progress), July 2016.		ping-01 (work in progress), January 2017.
	[RFC1191] Mogul, J. and S. Deering, "Path MTU discovery", RFC 1191,		[RFC1191] Mogul, J. and S. Deering, "Path MTU discovery", RFC 1191,
	DOI 10.17487/RFC1191, November 1990,		DOI 10.17487/RFC1191, November 1990,
	<http://www.rfc-editor.org/info/rfc1191>.		<http://www.rfc-editor.org/info/rfc1191>.
	[RFC1981] McCann, J., Deering, S., and J. Mogul, "Path MTU Discovery
	for IP version 6", RFC 1981, DOI 10.17487/RFC1981, August
	1996, <http://www.rfc-editor.org/info/rfc1981>.
	[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate		[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
	Requirement Levels", BCP 14, RFC 2119,		Requirement Levels", BCP 14, RFC 2119,
	DOI 10.17487/RFC2119, March 1997,		DOI 10.17487/RFC2119, March 1997,
	<http://www.rfc-editor.org/info/rfc2119>.		<http://www.rfc-editor.org/info/rfc2119>.
	[RFC4821] Mathis, M. and J. Heffner, "Packetization Layer Path MTU		[RFC4821] Mathis, M. and J. Heffner, "Packetization Layer Path MTU
	Discovery", RFC 4821, DOI 10.17487/RFC4821, March 2007,		Discovery", RFC 4821, DOI 10.17487/RFC4821, March 2007,
	<http://www.rfc-editor.org/info/rfc4821>.		<http://www.rfc-editor.org/info/rfc4821>.
			[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
			2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
			May 2017, <http://www.rfc-editor.org/info/rfc8174>.
			[RFC8201] McCann, J., Deering, S., Mogul, J., and R. Hinden, Ed.,
			"Path MTU Discovery for IP version 6", STD 87, RFC 8201,
			DOI 10.17487/RFC8201, July 2017,
			<http://www.rfc-editor.org/info/rfc8201>.
	7.2. Informative References		7.2. Informative References
			[I-D.ietf-bier-architecture]
			Wijnands, I., Rosen, E., Dolganow, A., Przygienda, T., and
			S. Aldrin, "Multicast using Bit Index Explicit
			Replication", draft-ietf-bier-architecture-07 (work in
			progress), June 2017.
	[I-D.ietf-bier-oam-requirements]		[I-D.ietf-bier-oam-requirements]
	Mirsky, G., Nordmark, E., Pignataro, C., Kumar, N.,		Mirsky, G., Nordmark, E., Pignataro, C., Kumar, N.,
	Aldrin, S., Zheng, L., Chen, M., Akiya, N., and S.		Aldrin, S., Zheng, L., Chen, M., Akiya, N., and S.
	Pallagatti, "Operations, Administration and Maintenance		Pallagatti, "Operations, Administration and Maintenance
	(OAM) Requirements for Bit Index Explicit Replication		(OAM) Requirements for Bit Index Explicit Replication
	(BIER) Layer", draft-ietf-bier-oam-requirements-03 (work		(BIER) Layer", draft-ietf-bier-oam-requirements-03 (work
	in progress), January 2017.		in progress), January 2017.
	Authors' Addresses		Authors' Addresses
End of changes. 12 change blocks.
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