< draft-ietf-rtgwg-cl-use-cases-01.txt		draft-ietf-rtgwg-cl-use-cases-02.txt >
	RTGWG S. Ning		RTGWG S. Ning
	Internet-Draft Tata Communications		Internet-Draft Tata Communications
	Intended status: Informational A. Malis		Intended status: Informational A. Malis
	Expires: February 13, 2013 D. McDysan		Expires: August 8, 2013 D. McDysan
	Verizon		Verizon
	L. Yong		L. Yong
	Huawei USA		Huawei USA
	C. Villamizar		C. Villamizar
	Outer Cape Cod Network		Outer Cape Cod Network
	Consulting		Consulting
	August 12, 2012		February 4, 2013
	Composite Link Use Cases and Design Considerations		Composite Link Use Cases and Design Considerations
	draft-ietf-rtgwg-cl-use-cases-01		draft-ietf-rtgwg-cl-use-cases-02
	Abstract		Abstract
	This document provides a set of use cases and design considerations		This document provides a set of use cases and design considerations
	for composite links.		for composite links.
	Composite link is a formalization of multipath techniques currently		Composite link is a formalization of multipath techniques currently
	in use in IP and MPLS networks and a set of extensions to multipath		in use in IP and MPLS networks and a set of extensions to multipath
	techniques.		techniques.
	skipping to change at page 1, line 42 ¶		skipping to change at page 1, line 42 ¶
	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 February 13, 2013.		This Internet-Draft will expire on August 8, 2013.
	Copyright Notice		Copyright Notice
	Copyright (c) 2012 IETF Trust and the persons identified as the		Copyright (c) 2013 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
	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 2, line 35 ¶		skipping to change at page 2, line 35 ¶
	7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12		7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
	8. Security Considerations . . . . . . . . . . . . . . . . . . . 12		8. Security Considerations . . . . . . . . . . . . . . . . . . . 12
	9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 13		9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 13
	10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13		10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
	10.1. Normative References . . . . . . . . . . . . . . . . . . . 13		10.1. Normative References . . . . . . . . . . . . . . . . . . . 13
	10.2. Informative References . . . . . . . . . . . . . . . . . . 13		10.2. Informative References . . . . . . . . . . . . . . . . . . 13
	Appendix A. More Details on Existing Network Operator		Appendix A. More Details on Existing Network Operator
	Practices and Protocol Usage . . . . . . . . . . . . 15		Practices and Protocol Usage . . . . . . . . . . . . 15
	Appendix B. Existing Multipath Standards and Techniques . . . . . 17		Appendix B. Existing Multipath Standards and Techniques . . . . . 17
	B.1. Common Multpath Load Spliting Techniques . . . . . . . . . 18		B.1. Common Multpath Load Spliting Techniques . . . . . . . . . 18
	B.2. Simple and Adaptive Load Balancing Multipath . . . . . . . 19		B.2. Static and Dynamic Load Balancing Multipath . . . . . . . 19
	B.3. Traffic Split over Parallel Links . . . . . . . . . . . . 20		B.3. Traffic Split over Parallel Links . . . . . . . . . . . . 20
	B.4. Traffic Split over Multiple Paths . . . . . . . . . . . . 20		B.4. Traffic Split over Multiple Paths . . . . . . . . . . . . 20
	Appendix C. Characteristics of Transport in Core Networks . . . . 20		Appendix C. Characteristics of Transport in Core Networks . . . . 20
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 22		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 22
	1. Introduction		1. Introduction
	Composite link requirements are specified in		Composite link requirements are specified in
	[I-D.ietf-rtgwg-cl-requirement]. A composite link framework is		[I-D.ietf-rtgwg-cl-requirement]. A composite link framework is
	defined in [I-D.ietf-rtgwg-cl-framework].		defined in [I-D.ietf-rtgwg-cl-framework].
	skipping to change at page 19, line 26 ¶		skipping to change at page 19, line 26 ¶
	the scope of this document.		the scope of this document.
	The current load balancing techniques are referenced in [RFC4385] and		The current load balancing techniques are referenced in [RFC4385] and
	[RFC4928]. The use of three hash based approaches are described in		[RFC4928]. The use of three hash based approaches are described in
	[RFC2991] and [RFC2992]. A mechanism to identify flows within PW is		[RFC2991] and [RFC2992]. A mechanism to identify flows within PW is
	described in [RFC6391]. The use of hash based approaches is		described in [RFC6391]. The use of hash based approaches is
	mentioned as an example of an existing set of techniques to		mentioned as an example of an existing set of techniques to
	distribute traffic over a set of component links. Other techniques		distribute traffic over a set of component links. Other techniques
	are not precluded.		are not precluded.
	B.2. Simple and Adaptive Load Balancing Multipath		B.2. Static and Dynamic Load Balancing Multipath
	Simple multipath generally relies on the mathematical probability		Static multipath generally relies on the mathematical probability
	that given a very large number of small microflows, these microflows		that given a very large number of small microflows, these microflows
	will tend to be distributed evenly across a hash space. Early very		will tend to be distributed evenly across a hash space. Early very
	simple multipath implementations assumed that all component links are		static multipath implementations assumed that all component links are
	of equal capacity and perform a modulo operation across the hashed		of equal capacity and perform a modulo operation across the hashed
	value. An alternate simple multipath technique uses a table		value. An alternate static multipath technique uses a table
	generally with a power of two size, and distributes the table entries		generally with a power of two size, and distributes the table entries
	proportionally among component links according to the capacity of		proportionally among component links according to the capacity of
	each component link.		each component link.
	Simple load balancing works well if there are a very large number of		Static load balancing works well if there are a very large number of
	small microflows (i.e., microflow rate is much less than component		small microflows (i.e., microflow rate is much less than component
	link capacity). However, the case where there are even a few large		link capacity). However, the case where there are even a few large
	microflows is not handled well by simple load balancing.		microflows is not handled well by static load balancing.
	An adaptive load balancing multipath technique is one where the		A dynamic load balancing multipath technique is one where the traffic
	traffic bound to each component link is measured and the load split		bound to each component link is measured and the load split is
	is adjusted accordingly. As long as the adjustment is done within a		adjusted accordingly. As long as the adjustment is done within a
	single network element, then no protocol extensions are required and		single network element, then no protocol extensions are required and
	there are no interoperability issues.		there are no interoperability issues.
	Note that if the load balancing algorithm and/or its parameters is		Note that if the load balancing algorithm and/or its parameters is
	adjusted, then packets in some flows may be briefly delivered out of		adjusted, then packets in some flows may be briefly delivered out of
	sequence, however in practice such adjustments can be made very		sequence, however in practice such adjustments can be made very
	infrequent.		infrequent.
	B.3. Traffic Split over Parallel Links		B.3. Traffic Split over Parallel Links
	skipping to change at page 23, line 6 ¶		skipping to change at page 23, line 6 ¶
	techniques are likely here to stay.		techniques are likely here to stay.
	Authors' Addresses		Authors' Addresses
	So Ning		So Ning
	Tata Communications		Tata Communications
	Email: ning.so@tatacommunications.com		Email: ning.so@tatacommunications.com
	Andrew Malis		Andrew Malis
	Verizon		Verizon
	117 West St.		60 Sylvan Road
	Waltham, MA 02451		Waltham, MA 02451
	Phone: +1 781-466-2362		Phone: +1 781-466-2362
	Email: andrew.g.malis@verizon.com		Email: andrew.g.malis@verizon.com
	Dave McDysan		Dave McDysan
	Verizon		Verizon
	22001 Loudoun County PKWY		22001 Loudoun County PKWY
	Ashburn, VA 20147		Ashburn, VA 20147
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