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.
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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
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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].
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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
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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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