< draft-ietf-bier-entropy-staged-dc-clos-02.txt		draft-ietf-bier-entropy-staged-dc-clos-03.txt >
	Network Working Group J. Xie		Network Working Group J. Xie
	Internet-Draft Huawei Technologies		Internet-Draft Huawei Technologies
	Intended status: Informational X. Xu		Intended status: Informational X. Xu
	Expires: May 7, 2020 Alibaba Inc.		Expires: November 7, 2020 Alibaba Inc.
	G. Yan		G. Yan
	Huawei Technologies		Huawei Technologies
	M. McBride		M. McBride
	Futurewei		Futurewei
	November 4, 2019		May 6, 2020
	Use of BIER Entropy for Data Center Clos Networks		Use of BIER Entropy for Data Center Clos Networks
	draft-ietf-bier-entropy-staged-dc-clos-02		draft-ietf-bier-entropy-staged-dc-clos-03
	Abstract		Abstract
	Bit Index Explicit Replication (BIER) introduces a new multicast-		Bit Index Explicit Replication (BIER) introduces a new multicast-
	specific BIER Header. BIER can be applied to the Multi Protocol		specific BIER Header. BIER can be applied to the Multi Protocol
	Label Switching (MPLS) data plane or Non-MPLS data plane. Entropy is		Label Switching (MPLS) data plane or Non-MPLS data plane. Entropy is
	a technique used in BIER to support load-balancing. This document		a technique used in BIER to support load-balancing. This document
	examines and describes how BIER Entropy is to be applied to Data		examines and describes how BIER Entropy is to be applied to Data
	Center Clos networks for path selection.		Center Clos networks for path selection.
	skipping to change at page 1, line 48 ¶		skipping to change at page 1, line 48 ¶
	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 https://datatracker.ietf.org/drafts/current/.		Drafts is at https://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 May 7, 2020.		This Internet-Draft will expire on November 7, 2020.
	Copyright Notice		Copyright Notice
	Copyright (c) 2019 IETF Trust and the persons identified as the		Copyright (c) 2020 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
	(https://trustee.ietf.org/license-info) in effect on the date of		(https://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
	carefully, as they describe your rights and restrictions with respect		carefully, as they describe your rights and restrictions with respect
	to this document. Code Components extracted from this document must		to this document. Code Components extracted from this document must
	include Simplified BSD License text as described in Section 4.e of		include Simplified BSD License text as described in Section 4.e of
	the Trust Legal Provisions and are provided without warranty as		the Trust Legal Provisions and are provided without warranty as
	skipping to change at page 4, line 44 ¶		skipping to change at page 4, line 44 ¶
	Multicast (BUM) traffic, a network operator may want a deterministic		Multicast (BUM) traffic, a network operator may want a deterministic
	path for every packet. For example, when L1 needs to send a BUM		path for every packet. For example, when L1 needs to send a BUM
	packet to L3 and L4, which are in different SIs, L1 has to send the		packet to L3 and L4, which are in different SIs, L1 has to send the
	packet twice, and expects the packet along two deterministic paths of		packet twice, and expects the packet along two deterministic paths of
	L1->S1->S11-->L3 and L1->S2->S21-->L4 seperately. Another example of		L1->S1->S11-->L3 and L1->S2->S21-->L4 seperately. Another example of
	using a deterministic path in a DC is for per-flow steering of		using a deterministic path in a DC is for per-flow steering of
	"elephant" flows defined in [I-D.ietf-spring-segment-routing-msdc].		"elephant" flows defined in [I-D.ietf-spring-segment-routing-msdc].
	A deterministic path for a multicast packet, with multiple staged		A deterministic path for a multicast packet, with multiple staged
	equal cost paths, is comparable to a traffic-engineering path defined		equal cost paths, is comparable to a traffic-engineering path defined
	in [I-D.ietf-mpls-spring-entropy-label] for a unicast path with		in [RFC8662] for a unicast path with multiple hop equal cost paths.
	multiple hop equal cost paths.
	3.2. Considerations		3.2. Considerations
	The idea behind entropy is that the ingress router computes a hash		The idea behind entropy is that the ingress router computes a hash
	based on several fields from a given packet and places the result in		based on several fields from a given packet and places the result in
	an additional label, named "entropy label". Then this entropy label		an additional label, named "entropy label". Then this entropy label
	can be used as part of the hash keys used by an transit router. When		can be used as part of the hash keys used by an transit router. When
	entropy label is used, the keys used in the hashing functions are		entropy label is used, the keys used in the hashing functions are
	still a local configuration matter. A router may soley use the		still a local configuration matter. A router may soley use the
	entropy label or use a combination of multiple fields from the		entropy label or use a combination of multiple fields from the
	skipping to change at page 7, line 41 ¶		skipping to change at page 7, line 41 ¶
	8. Acknowledgements		8. Acknowledgements
	The authors wish to thank Tony Przygienda, Greg Shepherd, Alia Atlas,		The authors wish to thank Tony Przygienda, Greg Shepherd, Alia Atlas,
	Jeffery Zhang, Andrew Dolganow, and Toerless Eckert for their		Jeffery Zhang, Andrew Dolganow, and Toerless Eckert for their
	reviews, comments and suggestions.		reviews, comments and suggestions.
	9. References		9. References
	9.1. Normative References		9.1. Normative References
	[I-D.ietf-mpls-spring-entropy-label]
	Kini, S., Kompella, K., Sivabalan, S., Litkowski, S.,
	Shakir, R., and J. Tantsura, "Entropy label for SPRING
	tunnels", draft-ietf-mpls-spring-entropy-label-12 (work in
	progress), July 2018.
	[I-D.ietf-spring-segment-routing-msdc]		[I-D.ietf-spring-segment-routing-msdc]
	Filsfils, C., Previdi, S., Dawra, G., Aries, E., and P.		Filsfils, C., Previdi, S., Dawra, G., Aries, E., and P.
	Lapukhov, "BGP-Prefix Segment in large-scale data		Lapukhov, "BGP-Prefix Segment in large-scale data
	centers", draft-ietf-spring-segment-routing-msdc-11 (work		centers", draft-ietf-spring-segment-routing-msdc-11 (work
	in progress), November 2018.		in progress), November 2018.
	[RFC7938] Lapukhov, P., Premji, A., and J. Mitchell, Ed., "Use of		[RFC7938] Lapukhov, P., Premji, A., and J. Mitchell, Ed., "Use of
	BGP for Routing in Large-Scale Data Centers", RFC 7938,		BGP for Routing in Large-Scale Data Centers", RFC 7938,
	DOI 10.17487/RFC7938, August 2016,		DOI 10.17487/RFC7938, August 2016,
	<https://www.rfc-editor.org/info/rfc7938>.		<https://www.rfc-editor.org/info/rfc7938>.
	skipping to change at page 8, line 28 ¶		skipping to change at page 8, line 23 ¶
	for Bit Index Explicit Replication (BIER) in MPLS and Non-		for Bit Index Explicit Replication (BIER) in MPLS and Non-
	MPLS Networks", RFC 8296, DOI 10.17487/RFC8296, January		MPLS Networks", RFC 8296, DOI 10.17487/RFC8296, January
	2018, <https://www.rfc-editor.org/info/rfc8296>.		2018, <https://www.rfc-editor.org/info/rfc8296>.
	[RFC8365] Sajassi, A., Ed., Drake, J., Ed., Bitar, N., Shekhar, R.,		[RFC8365] Sajassi, A., Ed., Drake, J., Ed., Bitar, N., Shekhar, R.,
	Uttaro, J., and W. Henderickx, "A Network Virtualization		Uttaro, J., and W. Henderickx, "A Network Virtualization
	Overlay Solution Using Ethernet VPN (EVPN)", RFC 8365,		Overlay Solution Using Ethernet VPN (EVPN)", RFC 8365,
	DOI 10.17487/RFC8365, March 2018,		DOI 10.17487/RFC8365, March 2018,
	<https://www.rfc-editor.org/info/rfc8365>.		<https://www.rfc-editor.org/info/rfc8365>.
			[RFC8662] Kini, S., Kompella, K., Sivabalan, S., Litkowski, S.,
			Shakir, R., and J. Tantsura, "Entropy Label for Source
			Packet Routing in Networking (SPRING) Tunnels", RFC 8662,
			DOI 10.17487/RFC8662, December 2019,
			<https://www.rfc-editor.org/info/rfc8662>.
	9.2. Informative References		9.2. Informative References
	[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,
	<https://www.rfc-editor.org/info/rfc2119>.		<https://www.rfc-editor.org/info/rfc2119>.
	[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC		[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
	2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,		2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
	May 2017, <https://www.rfc-editor.org/info/rfc8174>.		May 2017, <https://www.rfc-editor.org/info/rfc8174>.
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