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Internet Engineering Task Force (IETF) C. Villamizar, Ed.
Request for Comments: 7226 OCCNC, LLC
Category: Informational D. McDysan, Ed.
ISSN: 2070-1721 Verizon
S. Ning
Tata Communications
A. Malis
Huawei
L. Yong
Huawei USA
May 2014
Requirements for Advanced Multipath in MPLS Networks
Abstract
This document provides a set of requirements for Advanced Multipath
in MPLS networks.
Advanced Multipath is a formalization of multipath techniques
currently in use in IP and MPLS networks and a set of extensions to
existing multipath techniques.
Status of This Memo
This document is not an Internet Standards Track specification; it is
published for informational purposes.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Not all documents
approved by the IESG are a candidate for any level of Internet
Standard; see Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc7226.
Villamizar, et al. Informational [Page 1]
RFC 7226 Advanced Multipath Requirements May 2014
Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Functional Requirements . . . . . . . . . . . . . . . . . . . 6
3.1. Availability, Stability, and Transient Response . . . . . 6
3.2. Component Links Provided by Lower-Layer Networks . . . . 7
3.3. Component Links with Different Characteristics . . . . . 8
3.4. Considerations for Bidirectional Client LSP . . . . . . . 9
3.5. Multipath Load-Balancing Dynamics . . . . . . . . . . . . 10
4. General Requirements for Protocol Solutions . . . . . . . . . 12
5. Management Requirements . . . . . . . . . . . . . . . . . . . 13
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 14
7. Security Considerations . . . . . . . . . . . . . . . . . . . 14
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 15
8.1. Normative References . . . . . . . . . . . . . . . . . . 15
8.2. Informative References . . . . . . . . . . . . . . . . . 15
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1. Introduction
There is often a need to provide large aggregates of bandwidth that
are best provided using parallel links between routers or carrying
traffic over multiple MPLS Label Switched Paths (LSPs). In core
networks, there is often no alternative since the aggregate
capacities of core networks today far exceed the capacity of a single
physical link or a single packet-processing element.
The presence of parallel links, with each link potentially comprised
of multiple layers, has resulted in additional requirements. Certain
services may benefit from being restricted to a subset of the
component links or a specific component link, where component link
characteristics, such as latency, differ. Certain services require
that an LSP be treated as atomic and avoid reordering. Other
services will continue to require only that reordering not occur
within a flow as is current practice.
Numerous forms of multipath exist today, including MPLS Link Bundling
[RFC4201], Ethernet Link Aggregation [IEEE-802.1AX], and various
forms of Equal Cost Multipath (ECMP) such as for OSPF ECMP, IS-IS
ECMP, and BGP ECMP. Refer to the appendices in [USE-CASES] for a
description of existing techniques and a set of references.
The purpose of this document is to clearly enumerate a set of
requirements related to the protocols and mechanisms that provide
MPLS-based Advanced Multipath. The intent is to first provide a set
of functional requirements, in Section 3, that are as independent as
possible of protocol specifications. A set of general protocol
requirements are defined in Section 4. A set of network management
requirements are defined in Section 5.
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
Any statement that requires the solution to support some new
functionality through use of [RFC2119] keywords should be interpreted
as follows. The implementation either MUST or SHOULD support the new
functionality, depending on the use of either MUST or SHOULD in the
requirements statement. The implementation SHOULD, in most or all
cases, allow any new functionality to be individually enabled or
disabled through configuration. A service provider or other
deployment MAY enable or disable any feature in their network,
subject to implementation limitations on sets of features that can be
disabled.
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2. Definitions
Multipath
The term "multipath" includes all techniques in which:
1. Traffic can take more than one path from one node to a
destination.
2. Individual packets take one path only. Packets are not
subdivided and reassembled at the receiving end.
3. Packets are not resequenced at the receiving end.
4. The paths may be:
a. parallel links between two nodes,
b. specific paths across a network to a destination node, or
c. links or paths to an intermediate node used to reach a
common destination.
The paths need not have equal capacity. The paths may or may not
have equal cost in a routing protocol.
Advanced Multipath
Advanced Multipath is a formalization of multipath techniques
that meets the requirements defined in this document. A key
capability of Advanced Multipath is the support of non-
homogeneous component links.
Advanced Multipath Group (AMG)
An AMG is a collection of component links where Advanced
Multipath techniques are applied.
Composite Link
The term "composite link" had been a registered trademark of
Avici Systems, but it was abandoned in 2007. The term "composite
link" is now defined by the ITU-T in [ITU-T.G.800]. The ITU-T
definition includes multipath as defined here, plus inverse
multiplexing, which is explicitly excluded from the definition of
multipath.
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Inverse Multiplexing
Inverse multiplexing is another method of sending traffic over
multiple links. Inverse multiplexing either transmits whole
packets and resequences the packets at the receiving end or
subdivides packets and reassembles the packets at the receiving
end. Inverse multiplexing requires that all packets be handled
by a common egress packet processing element and is, therefore,
not useful for very high-bandwidth applications.
Component Link
The ITU-T definition of composite link in [ITU-T.G.800] and the
IETF definition of link bundling in [RFC4201] both refer to an
individual link in the composite link or link bundle as a
component link. The term "component link" is applicable to all
forms of multipath. The IEEE uses the term "member" rather than
"component link" in Ethernet Link Aggregation [IEEE-802.1AX].
Client Layer
A client layer is the layer immediately above a server layer.
Server Layer
A server layer is the layer immediately below a client layer.
Higher Layers
Relative to a particular layer, a client layer and any layer
above that is considered a higher layer. Upper layer is
synonymous with higher layer.
Lower Layers
Relative to a particular layer, a server layer and any layer
below that is considered a lower layer.
Client LSP
A client LSP is an LSP that has been set up over one or more
lower layers. In the context of this discussion, one type of
client LSP is an LSP that has been set up over an AMG.
Flow
A sequence of packets that should be transferred in order on one
component link of a multipath.
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Flow Identification
The label stack and other information that uniquely identifies a
flow. Other information in flow identification may include an IP
header, pseudowire (PW) control word, Ethernet Media Access
Control (MAC) address, etc. Note that a client LSP may contain
one or more flows, or a client LSP may be equivalent to a flow.
Flow identification is used to locally select a component link or
a path through the network toward the destination.
Load Balance
Load split, load balance, or load distribution refers to
subdividing traffic over a set of component links such that load
is fairly evenly distributed over the set of component links and
certain packet ordering requirements are met. Some existing
techniques better achieve these objectives than others.
Performance Objective
Numerical values for performance measures: principally
availability, latency, and delay variation. Performance
objectives may be related to Service Level Agreements (SLAs) as
defined in [RFC2475] or may be strictly internal. Performance
objectives may span links from edge to edge or from end to end.
Performance objectives may span one provider or multiple
providers.
A component link may be a point-to-point physical link (where a
"physical link" includes one or more link layers, plus a physical
layer) or a logical link that preserves ordering in the steady state.
A component link may have transient out-of-order events, but such
events must not exceed the network's performance objectives. For
example, a component link may be comprised of any supportable
combination of link layers over a physical layer or over logical sub-
layers -- including those providing physical-layer emulation -- or
over MPLS server-layer LSP.
The ingress and egress of a multipath may be midpoint LSRs with
respect to a given client LSP. A midpoint LSR does not participate
in the signaling of any clients of the client LSP. Therefore, in
general, multipath endpoints cannot determine requirements of clients
of a client LSP through participation in the signaling of the clients
of the client LSP.
This document makes no statement on whether Advanced Multipath is
itself a layer or whether an instance of AMG is itself a layer. This
is to avoid engaging in long and pointless discussions about what
constitutes a proper layer.
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The term "Advanced Multipath" is intended to be used within the
context described in this document and related documents, for
example, [USE-CASES] and [FRAMEWORK]. Other Advanced Multipath
techniques may arise in the future. If the capabilities defined in
this document become commonplace, they would no longer be considered
"advanced". Use of the term "advanced multipath" outside this
document, if referring to the term as defined here, should indicate
Advanced Multipath as defined by this document, citing the current
document name. If using another definition of "advanced multipath",
documents may optionally clarify that they are not using the term
"advanced multipath" as defined by this document if clarification is
deemed helpful.
3. Functional Requirements
The functional requirements in this section are grouped in
subsections, starting with the highest priority.
3.1. Availability, Stability, and Transient Response
In addition to maintaining stability, limiting the period of
unavailability in response to failures or transient events is
extremely important.
FR#1 The transient period between some service disrupting event and
the convergence of the routing and/or signaling protocols MUST
occur within a time frame specified by performance objective
values.
FR#2 An AMG MAY be announced in conjunction with detailed parameters
about its component links, such as bandwidth and latency. The
AMG SHALL behave as a single IGP adjacency.
FR#3 The solution SHALL provide a means to summarize some routing
advertisements regarding the characteristics of an AMG such
that the updated protocol mechanisms maintain convergence times
within the time frame needed to meet or not significantly
exceed existing performance objectives for convergence on the
same network or convergence on a network with a similar
topology.
FR#4 The solution SHALL ensure that restoration operations happen
within the time frame needed to meet existing performance
objectives for restoration time on the same network or
restoration time on a network with a similar topology.
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FR#5 The solution shall provide a mechanism to select a set of paths
for an LSP across a network in such a way that flows within the
LSP are distributed across the set of paths, while meeting all
of the other requirements stated above. The solution SHOULD
work in a manner similar to existing multipath techniques,
except as necessary to accommodate Advanced Multipath
requirements.
FR#6 If extensions to existing protocols are specified and/or new
protocols are defined, then the solution SHOULD provide a means
for a network operator to migrate an existing deployment in a
minimally disruptive manner.
FR#7 Any load-balancing solutions MUST NOT oscillate. Some change
in path MAY occur. The solution MUST ensure that path
stability and traffic reordering continue to meet performance
objectives on the same network or on a network with a similar
topology. Since oscillation may cause reordering, there MUST
be means to control the frequency of changing the component
link over which a flow is placed.
FR#8 Management and diagnostic protocols MUST be able to operate
over AMGs.
Existing scaling techniques used in MPLS networks apply to MPLS
networks that support Advanced Multipath. Scalability and stability
are covered in more detail in [FRAMEWORK].
3.2. Component Links Provided by Lower-Layer Networks
A component link may be supported by a lower-layer network. For
example, the lower layer may be a circuit-switched network or another
MPLS network (e.g., MPLS Transport Profile (MPLS-TP)). The lower-
layer network may change the latency (and/or other performance
parameters) seen by the client layer. Currently, there is no
protocol for the lower-layer network to inform the higher-layer
network of a change in a performance parameter. Communication of the
latency performance parameter is a very important requirement.
Communication of other performance parameters (e.g., delay variation)
is desirable.
FR#9 The solution SHALL specify a protocol means to allow a server-
layer network to communicate latency to the client-layer
network.
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FR#10 The precision of latency reporting SHOULD be configurable. A
reasonable default SHOULD be provided. Implementations SHOULD
support precision of at least 10% of the one-way latencies for
latency of 1 msec or more.
The intent is to measure the predominant latency in uncongested
service-provider networks, where geographic delay dominates and is on
the order of milliseconds or more. The argument for including
queuing delay is that it reflects the delay experienced by
applications. The argument against including queuing delay is that
if used in routing decisions, it can result in routing instability.
This trade-off is discussed in detail in [FRAMEWORK].
3.3. Component Links with Different Characteristics
As one means to provide high availability, network operators deploy a
topology in the MPLS network using lower-layer networks that have a
certain degree of diversity at the lower layer(s). Many techniques
have been developed to balance the distribution of flows across
component links that connect the same pair of nodes or ultimately
lead to a common destination.
FR#11 In the requirements that follow in this document, the word
"indicate" is used where information may be provided by either
the combination of link state IGP advertisement and MPLS LSP
signaling or via management plane protocols. In later
documents, providing framework and protocol definitions, both
signaling and management plane mechanisms, MUST be defined.
FR#12 The solution SHALL provide a means for the client layer to
indicate a requirement that a client LSP will traverse a
component link with the minimum-latency value. This will
provide a means by which minimum latency performance objectives
of flows within the client LSP can be supported.
FR#13 The solution SHALL provide a means for the client layer to
indicate a requirement that a client LSP will traverse a
component link with a maximum acceptable latency value as
specified by protocol. This will provide a means by which
bounded latency performance objectives of flows within the
client LSP can be supported.
FR#14 The solution SHALL provide a means for the client layer to
indicate a requirement that a client LSP will traverse a
component link with a maximum acceptable delay variation value
as specified by protocol.
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The above set of requirements applies to component links with
different characteristics, regardless of whether those component
links are provided by parallel physical links between nodes or by
sets of paths across a network provided by a server-layer LSP.
Allowing multipath to contain component links with different
characteristics can improve the overall load balance and can be
accomplished while still accommodating the more strict requirements
of a subset of client LSP.
3.4. Considerations for Bidirectional Client LSP
Some client LSPs MAY require a path bound to a specific set of
component links. This case is most likely to occur in a
bidirectional client LSP where time synchronization protocols such as
the Precision Time Protocol (PTP) or the Network Time Protocol (NTP)
are carried or in any other case where symmetric delay is highly
desirable. There may be other uses of this capability.
Other client LSPs may only require that the LSP serve the same set of
nodes in both directions. This is necessary if protocols are carried
that make use of the reverse direction of the LSP as a back channel
in cases such Operations, Administration, and Maintenance (OAM)
protocols using IPv4 Time to Live (TTL) or IPv4 Hop Limit to monitor
or diagnose the underlying path. There may be other uses of this
capability.
FR#15 The solution SHALL provide a means for the client layer to
indicate a requirement that a client LSP be bound to a
particular component link within an AMG. If this option is not
exercised, then a client LSP that is carried over an AMG may be
bound to any component link or set of component links matching
all other signaled requirements, and different directions of a
bidirectional client LSP can be bound to different component
links.
FR#16 The solution MUST support a means for the client layer to
indicate a requirement that for a specific co-routed
bidirectional client LSP, both directions of the co-routed
bidirectional client LSP MUST be bound to the same set of
nodes.
FR#17 A client LSP that is bound to a specific component link SHOULD
NOT exceed the capacity of a single component link. This is
inherent in the assumption that a network SHOULD NOT operate in
a congested state if congestion is avoidable.
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For some large bidirectional client LSPs, it may not be necessary (or
possible due to the client LSP capacity) to bind the LSP to a common
set of component links, but it may be necessary or desirable to
constrain the path taken by the LSP to the same set of nodes in both
directions. Without an entirely new and highly dynamic protocol, it
is not feasible to constrain such a bidirectional client LSP from
taking multiple paths and coordinating load balance on each side in
order to keep both directions of flows within such an LSP on common
paths.
3.5. Multipath Load-Balancing Dynamics
Multipath load balancing attempts to keep traffic levels on all
component links below congestion levels if possible and preferably
well balanced. Load balancing is minimally disruptive (see the
discussion below this section's list of requirements). The
sensitivity to these minimal disruptions of traffic flows within a
specific client LSP needs to be considered.
FR#18 The solution SHALL provide a means for the client layer to
indicate a requirement that a specific client LSP MUST NOT be
split across multiple component links.
FR#19 The solution SHALL provide a means local to a node that
automatically distributes flows across the component links in
the AMG such that performance objectives are met, as described
in the prior requirements in Section 3.3.
FR#20 The solution SHALL measure traffic flows or groups of traffic
flows and dynamically select the component link on which to
place this traffic in order to balance the load so that no
component link in the AMG between a pair of nodes is
overloaded.
FR#21 When a traffic flow is moved from one component link to another
in the same AMG between a set of nodes, it MUST be done so in a
minimally disruptive manner.
FR#22 Load balancing MAY be used during sustained low-traffic periods
to reduce the number of active component links for the purpose
of power reduction.
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FR#23 The solution SHALL provide a means for the client layer to
indicate a requirement that a specific client LSP contains
traffic whose frequency of component link change due to load
balancing needs to be bounded by a specific value. The
solution MUST provide a means to bound the frequency of a
component link change due to load balancing for subsets of
traffic flow on AMGs.
FR#24 The solution SHALL provide a means to distribute traffic flows
from a single client LSP across multiple component links to
handle at least the case where the traffic carried in a client
LSP exceeds that of any component link in the AMG.
FR#25 The solution SHOULD support the use case where an AMG itself is
a component link for a higher order AMG. For example, an AMG
comprised of MPLS-TP bidirectional tunnels viewed as logical
links could then be used as a component link in yet another AMG
that connects MPLS routers.
FR#26 If the total demand offered by traffic flows exceeds the
capacity of the AMG, the solution SHOULD define a means to
cause some client LSPs to move to an alternate set of paths
that are not congested. These "preempted LSPs" may not be
restored if there is no uncongested path in the network.
A minimally disruptive change implies that as little disruption as is
practical occurs. Such a change can be achieved with zero packet
loss. A delay discontinuity may occur, which is considered to be a
minimally disruptive event for most services if this type of event is
sufficiently rare. A delay discontinuity is an example of a
minimally disruptive behavior corresponding to current techniques.
A delay discontinuity is an isolated event that may greatly exceed
the normal delay variation (jitter). A delay discontinuity has the
following effect. When a flow is moved from a current link to a
target link with lower latency, reordering can occur. When a flow is
moved from a current link to a target link with a higher latency, a
time gap can occur. Some flows (e.g., timing distribution and PW
circuit emulation) are quite sensitive to these effects. A delay
discontinuity can also cause a jitter buffer underrun or overrun,
affecting user experience in real-time voice services (causing an
audible click). These sensitivities may be specified in a
performance objective.
As with any load-balancing change, a change initiated for the purpose
of power reduction may be minimally disruptive. Typically, the
disruption is limited to a change in delay characteristics and the
potential for a very brief period with traffic reordering. When
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configuring a network for power reduction, the network operator
should weigh the benefit of power reduction against the disadvantage
of a minimal disruption.
4. General Requirements for Protocol Solutions
This section defines requirements for protocol specifications used to
meet the functional requirements specified in Section 3.
GR#1 The solution SHOULD extend existing protocols wherever
possible, developing a new protocol only where doing so adds a
significant set of capabilities.
GR#2 A solution SHOULD extend LDP capabilities to meet functional
requirements. This MUST be accomplished without defining LDP
Traffic Engineering (TE) methods as decided in [RFC3468].
GR#3 Coexistence of LDP- and RSVP-TE-signaled LSPs MUST be supported
on an AMG. Function requirements SHOULD, where possible, be
accommodated in a manner that supports LDP-signaled LSP, RSVP-
signaled LSP, and LSP setup using management plane mechanisms.
GR#4 When the nodes connected via an AMG are in the same routing
domain, the solution MAY define extensions to the IGP.
GR#5 When the nodes are connected via an AMG are in different MPLS
network topologies, the solution SHALL NOT rely on extensions
to the IGP.
GR#6 The solution SHOULD support AMG IGP advertisement that results
in convergence time better than that of advertising the
individual component links. The solution SHALL be designed so
that it represents the range of capabilities of the individual
component links such that functional requirements are met, and
it also minimizes the frequency of advertisement updates that
may cause IGP convergence to occur.
Examples of advertisement-update-triggering events to be
considered include: client LSP establishment/release, changes
in component-link characteristics (e.g., latency and up/down
state), and/or bandwidth utilization.
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GR#7 When a worst-case failure scenario occurs, the number of
RSVP-TE client LSPs to be resignaled will cause a period of
unavailability as perceived by users. The resignaling time of
the solution MUST support protocol mechanisms meeting existing
provider performance objectives for the duration of
unavailability without significantly relaxing those existing
performance objectives for the same network or for networks
with similar topology. For example, the processing load due to
IGP readvertisement MUST NOT increase significantly, and the
resignaling time of the solution MUST NOT increase
significantly as compared with current methods.
5. Management Requirements
MR#1 The Management Plane MUST support polling of the status and
configuration of an AMG and its individual component links and
support notification of status change.
MR#2 The Management Plane MUST be able to activate or deactivate any
component link in an AMG in order to facilitate operation
maintenance tasks. The routers at each end of an AMG MUST
redistribute traffic to move traffic from a deactivated link to
other component links based on the traffic flow TE criteria.
MR#3 The Management Plane MUST be able to configure a client LSP
over an AMG and be able to select a component link for the
client LSP.
MR#4 The Management Plane MUST be able to trace which component link
a client LSP is assigned to and monitor individual component
link and AMG performance.
MR#5 The Management Plane MUST be able to verify connectivity over
each individual component link within an AMG.
MR#6 Component link fault notification MUST be sent to the
management plane.
MR#7 AMG fault notification MUST be sent to the management plane and
MUST be distributed via a link state message in the IGP.
MR#8 The Management Plane SHOULD provide the means for an operator
to initiate an optimization process.
MR#9 An operator-initiated optimization MUST be performed in a
minimally disruptive manner, as described in Section 3.5.
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6. Acknowledgements
Frederic Jounay of France Telecom and Yuji Kamite of NTT
Communications Corporation coauthored a version of this document.
A rewrite of this document occurred after the IETF 77 meeting.
Dimitri Papadimitriou, Lou Berger, Tony Li, the former WG Chairs John
Scuder and Alex Zinin, the current WG Chair Alia Atlas, and others
provided valuable guidance prior to and at the IETF 77 RTGWG meeting.
Tony Li and John Drake have made numerous valuable comments on the
RTGWG mailing list that are reflected in versions following the IETF
77 meeting.
Iftekhar Hussain and Kireeti Kompella made comments on the RTGWG
mailing list after the IETF 82 meeting that identified a new
requirement. Iftekhar Hussain made numerous valuable comments on the
RTGWG mailing list that resulted in improvements to the document's
clarity.
In the interest of full disclosure of affiliation and in the interest
of acknowledging sponsorship, past affiliations of authors are noted
here. Much of the work done by Ning So and Andrew Malis occurred
while they were at Verizon. Much of the work done by Curtis
Villamizar occurred while he was at Infinera.
Tom Yu and Francis Dupont provided the SecDir and GenArt reviews,
respectively. Both reviews provided useful comments. The current
wording of the security section is based on suggested wording from
Tom Yu. Lou Berger provided the RtgDir review, which resulted in the
document being renamed and the substantial clarification of
terminology and document wording, particularly in the Abstract,
Introduction, and Definitions sections.
7. Security Considerations
The security considerations for MPLS/GMPLS and for MPLS-TP are
documented in [RFC5920] and [RFC6941]. This document does not impact
the security of MPLS, GMPLS, or MPLS-TP.
The additional information that this document requires does not
provide significant additional value to an attacker beyond the
information already typically available from attacking a routing or
signaling protocol. If the requirements of this document are met by
extending an existing routing or signaling protocol, the security
considerations of the protocol being extended apply. If the
requirements of this document are met by specifying a new protocol,
the security considerations of that new protocol should include an
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evaluation of what level of protection is required by the additional
information specified in this document, such as data origin
authentication.
8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
8.2. Informative References
[FRAMEWORK]
Ning, S., McDysan, D., Osborne, E., Yong, L., and C.
Villamizar, "Advanced Multipath Framework in MPLS", Work
in Progress, July 2013.
[IEEE-802.1AX]
IEEE Standards Association, "IEEE Std 802.1AX-2008 IEEE
Standard for Local and Metropolitan Area Networks - Link
Aggregation", 2006, <http://standards.ieee.org/getieee802/
download/802.1AX-2008.pdf>.
[ITU-T.G.800]
ITU-T, "Unified functional architecture of transport
networks", ITU-T Recommendation G.800, February 2012,
<http://www.itu.int/rec/T-REC-G/
recommendation.asp?parent=T-REC-G.800>.
[RFC2475] Blake, S., Black, D., Carlson, M., Davies, E., Wang, Z.,
and W. Weiss, "An Architecture for Differentiated
Services", RFC 2475, December 1998.
[RFC3468] Andersson, L. and G. Swallow, "The Multiprotocol Label
Switching (MPLS) Working Group decision on MPLS signaling
protocols", RFC 3468, February 2003.
[RFC4201] Kompella, K., Rekhter, Y., and L. Berger, "Link Bundling
in MPLS Traffic Engineering (TE)", RFC 4201, October 2005.
[RFC5920] Fang, L., "Security Framework for MPLS and GMPLS
Networks", RFC 5920, July 2010.
[RFC6941] Fang, L., Niven-Jenkins, B., Mansfield, S., and R.
Graveman, "MPLS Transport Profile (MPLS-TP) Security
Framework", RFC 6941, April 2013.
Villamizar, et al. Informational [Page 16]
RFC 7226 Advanced Multipath Requirements May 2014
[USE-CASES]
Ning, S., Malis, A., McDysan, D., Yong, L., and C.
Villamizar, "Advanced Multipath Use Cases and Design
Considerations", Work in Progress, November 2013.
Authors' Addresses
Curtis Villamizar (editor)
OCCNC, LLC
EMail: curtis@occnc.com
Dave McDysan (editor)
Verizon
22001 Loudoun County PKWY
Ashburn, VA 20147
USA
EMail: dave.mcdysan@verizon.com
So Ning
Tata Communications
EMail: ning.so@tatacommunications.com
Andrew G. Malis
Huawei Technologies
2330 Central Expressway
Santa Clara, CA 95050
USA
EMail: agmalis@gmail.com
Lucy Yong
Huawei USA
5340 Legacy Dr.
Plano, TX 75025
USA
Phone: +1 469-277-5837
EMail: lucy.yong@huawei.com
Villamizar, et al. Informational [Page 17]