wdiff draft-ietf-rtgwg-cl-requirement-10.txt draft-ietf-rtgwg-cl-requirement-11.txt

RTGWG C. Villamizar, Ed.
Internet-Draft OCCNC, LLC
Intended status: Informational D. McDysan, Ed.
Expires: September 23, 2013 January 12, 2014 Verizon
S. Ning
Tata Communications
A. Malis
Verizon
L. Yong
Huawei USA
March 22,
July 11, 2013

Requirements for Composite Links Advanced Multipath in MPLS Networks
draft-ietf-rtgwg-cl-requirement-10
draft-ietf-rtgwg-cl-requirement-11

Abstract

There is often

This document provides a need to provide large aggregates set of bandwidth that
are best provided using parallel links between routers or requirements for Advanced Multipath
in MPLS LSR.
In core networks there Networks.

Advanced Multipath is often no alternative since the aggregate
capacities of core networks today far exceed the capacity of a single
physical link or single packet processing element.

The presence of parallel links, with each link potentially comprised formalization of multiple layers has resulted multipath techniques
currently in additional requirements. Certain
services may benefit from being restricted to use in IP and MPLS networks and a subset set 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 extensions to require only that reordering not occur
within a microflow as is current practice.
existing multipath techniques.

Status of this Memo

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provisions of BCP 78 and BCP 79.

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This Internet-Draft will expire on September 23, 2013. January 12, 2014.

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Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 4 3
2. Assumptions Definitions . . . . . . . . . . . . . . . . . . . . . . . . . 4 3
3. Definitions . . . . . . . . . . . . . . . . . Functional Requirements . . . . . . . . 4
4. Network Operator Functional Requirements . . . . . . . . . . . 5
4.1. 6
3.1. Availability, Stability and Transient Response . . . . . . 5
4.2. 6
3.2. Component Links Provided by Lower Layer Networks . . . . . 6
4.3. 7
3.3. Parallel Component Links with Different Characteristics . 8
5.
4. Derived Requirements . . . . . . . . . . . . . . . . . . . . . 10
6. 11
5. Management Requirements . . . . . . . . . . . . . . . . . . . 11
7. 12
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 12
8. 13
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
9. 13
8. Security Considerations . . . . . . . . . . . . . . . . . . . 12
10. 13
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
10.1. 14
9.1. Normative References . . . . . . . . . . . . . . . . . . . 13
10.2. 14
9.2. Informative References . . . . . . . . . . . . . . . . . . 13
Appendix A. ITU-T G.800 Composite Link Definitions and
Terminology . . . . . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 15

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 LSP. 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 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 microflow as is current practice.

The purpose of this document is to describe why network operators
require certain functions in order clearly enumerate a set of
requirements related to solve certain business problems
(Section 2). the protocols and mechanisms that provide
MPLS based Advanced Multipath. The intent is to first describe why things need to be
done in terms provide a set
of functional requirements that are as independent as possible of
protocol specifications (Section 4). 3). For certain functional
requirements this document describes a set of derived protocol
requirements (Section 4) and management requirements (Section 5). Appendix A provides a summary of
G.800 terminology used to define a composite link.

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 RFC 2119 [RFC2119].

2. Assumptions

Any statement which requires the solution to support some new
functionality through use of [RFC2119] keywords, SHOULD be
interpretted as follows. The services supported include pseudowire based services (RFC 3985
[RFC3985]), including VPN services, Internet traffic encapsulated by
at least one MPLS label (RFC 3032 [RFC3032]), and dynamically
signaled MPLS (RFC 3209 [RFC3209] implementation either MUST or RFC 5036 [RFC5036]) SHOULD
support the new functionality depending on the use of either MUST or MPLS-TP
LSPs (RFC 5921 [RFC5921]).
SHOULD in the requirements statement. The MPLS LSPs supporting these services
may implementation SHOULD in
most or all cases allow any new functionality to be point-to-point, point-to-multipoint, individually
enabled or disabled through configuration. A service provider or multipoint-to-
multipoint.
other deployment MAY choose to enable or disable any feature in their
network, subject to implementation limitations on sets of features
which can be disabled.

2. Definitions
Multipath
The locations term multipath includes all techniques in which

1. Traffic can take more than one path from one node to a network where these requirements apply
destination.

2. Individual packets take one path only. Packets are a Label
Edge Router (LER) 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, or

b. may be specific paths across a Label Switch Router (LSR) as defined in RFC
3031 [RFC3031].

The IP DSCP cannot network to a destination
node, or

c. may be links or paths to an intermediate node used for flow identification since L3VPN
requires Diffserv transparency (see RFC 4031 5.5.2 [RFC4031]), and in
general network operators do to
reach a common destination.

The paths need not rely on have equal capacity. The paths may or may not
have equal cost in a routing protocol.

Advanced Multipath
Advanced Multipath meets the requirements defined in this
document. A key capability of advanced multipath is the DSCP support
of Internet
packets.

3. Definitions

ITU-T G.800 Based non-homogeneous component links.

Composite and Component Link Definitions:
Section 6.9.2
The term Composite Link had been a registered trademark of ITU-T-G.800 [ITU-T.G.800] defines composite and
component links as summarized Avici
Systems, but was abandoned in Appendix A. 2007. The following
definitions for composite and component links are derived from
and intended to be consistent with the cited ITU-T G.800
terminology.

Composite Link: A term composite link is a logical link composed of a
set of parallel point-to-point component links, where all
links
now defined by the ITU in [ITU-T.G.800]. The ITU definition
includes multipath as defined here, plus inverse multiplexing
which is explicitly excluded from the set share definition of multipath.

Inverse Multiplexing
Inverse multiplexing either transmits whole packets and
resequences the same endpoints. A composite link
may itself 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 component of another composite link, but only
a strict hierarchy of links
common egress packet processing element and is allowed. therefore not
useful for very high bandwidth applications.

Component Link: A point-to-point physical Link
The ITU definition of composite link (including one or
more in [ITU-T.G.800] and the
IETF definition of link layer) or a logical bundling in [RFC4201] both refer to an
individual link that preserves ordering in the steady state. A composite link or link bundle as a
component link. The term component link may have transient out is applicable to all
forms of
order events, but such events must not exceed multipath. The IEEE uses the network's
specific NPO. Examples of a physical term member rather than
component link are: any in Ethernet Link Aggregation [IEEE-802.1AX].

Client LSP
A client LSP is an LSP which has been set of
link layers up over a WDM wavelength or any supportable
combination server layer.
In the context of Ethernet PHY, PPP, SONET or OTN over this discussion, a
physical link. Examples of client LSP is a logical link are: MPLS LSP,
Ethernet VLAN, MPLS-TP LSP. A LSP which
has been set of link layers supported up over pseudowire is a logical link that appears multipath as opposed to an LSP
representing the client
to be multipath itself or any LSP supporting a physical link.

Flow:
component links of that multipath.

Flow
A sequence of packets that must should be transferred in order on one
component link. link of a multipath.

Flow identification: identification
The label stack and other information that uniquely identifies a
flow. Other information in flow identification may include an IP
header, PW pseudowire (PW) control word, Ethernet MAC address, etc.
Note that an a client LSP may contain one or more Flows or an 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.

Network

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 acheive these objectives than others.

Performance Objective (NPO):
Numerical values for performance measures, principally
availability, latency, and delay variation. See [I-D.ietf-rtgwg-cl-use-cases] for Performance
objectives may be related to Service Level Agreements (SLA) as
defined in RFC2475 or may be strictly internal. Performance
objectives may span links, edge-to-edge, or end-to-end.
Performance objectives may span one provider or may span multiple
providers.

A Component Link may be a point-to-point physical link (where a
"physical link" includes one or more
details.

4. Network Operator link layer 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 compoent 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.

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.

The term Advanced Multipath is intended to be used within the context
of this document and the related documents,
[I-D.ietf-rtgwg-cl-use-cases] and [I-D.ietf-rtgwg-cl-framework] and
any other related document. Other advanced multipath techniques may
in the future arise. 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
refering 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.

4.1.

3.1. Availability, Stability and Transient Response

Limiting the period of unavailability in response to failures or
transient events is extremely important as well as maintaining
stability. 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 NPO Performance Objective
values.
[I-D.ietf-rtgwg-cl-use-cases] provides references

FR#1 An advanced multipath MAY be announced in conjunction with
detailed parameters about its component links, such as
bandwidth and latency. The advanced multipath SHALL behave as
a summary of
service types requiring a range of restoration times.

FR#1 single IGP adjacency.

FR#2 The solution SHALL provide a means to summarize some routing
advertisements regarding the characteristics of a composite
link an advanced
multipath such that the routing updated protocol converges mechanisms maintain
convergence times within the timeframe needed to meet or no
significantly exceed existing Performance Objective for
convergence on the same network or convergence on a network performance objective. A
composite link CAN be announced in conjunction
with detailed
parameters about its component links, such as bandwidth and
latency. The composite link SHALL behave as a single IGP
adjacency.

FR#2 similar topology.

FR#3 The solution SHALL ensure that all possible restoration operations happen
within the timeframe needed to meet existing Performance
Objective for restoration time on the NPO.
The solution may need to specify same network or
restoration time on a means for aggregating
signaling to meet this requirement.

FR#3 network with a similar topology.

FR#4 The solution SHALL provide a mechanism to select a path for a
flow across a network that contains a number of paths comprised
of pairs of nodes connected by composite links advanced multipath in such a way
as to automatically distribute the load over the network nodes
connected by composite links advanced multipaths while meeting all of the other
mandatory requirements stated above. The solution SHOULD work
in a manner similar to that of current networks without any
composite link
advanced multipath protocol enhancements when the
characteristics of the individual component links are
advertised.

FR#4

FR#5 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#5

FR#6 Any automatic LSP routing and/or load balancing solutions MUST NOT oscillate such that performance observed by users changes
such oscillate. Some change
in path MAY occur. The solution MUST ensure that an NPO is violated. path
stability and traffic reordering continue to meet Performance
Objective 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#6

FR#7 Management and diagnostic protocols MUST be able to operate
over composite links. advanced multipaths.

Existing scaling techniques used in MPLS networks apply to MPLS
networks which support Composite Links. Advanced Multipaths. Scalability and
stability are covered in more detail in
[I-D.ietf-rtgwg-cl-framework].

4.2.

3.2. Component Links Provided by Lower Layer Networks

Case 3 as defined in [ITU-T.G.800] involves a

A component link
supporting an MPLS may be supported by a lower layer network over another network. For
example, the lower layer network
(e.g., may be a circuit switched network or another
MPLS network (e.g., MPLS-TP)). The lower layer network may change
the latency (and/or other performance parameters) seen by the MPLS layer network. Network
Operators have NPOs of which some components are based on performance
parameters. 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#7 In order to support network NPOs and provide acceptable user
experience, the

FR#8 The solution SHALL specify a protocol means to allow a lower
layer server network to communicate latency to the higher
layer client network.

FR#8

FR#9 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 ms or more.

FR#9

FR#10 The solution SHALL provide a means to limit the latency to
meet a Performance Objective target on a per LSP flow basis between nodes within a network to meet an NPO
target when the path between these nodes contains one or more
pairs
group of nodes connected via a composite link. flow basis, where flows or groups of flows are
identifiable in the forwarding plane and are signaled using in
the control plane or set up using the management plane.

The NPOs Performance Objectives differ across the services, and
some services have different NPOs Performance Objectives for
different QoS classes, for example, one QoS class may have a
much larger latency bound than another. Overload can occur
which would violate an NPO a Performance Objective parameter (e.g.,
loss) and some remedy to handle this case for a composite link an advanced
multipath is required.

FR#10

FR#11 If the total demand offered by traffic flows exceeds the
capacity of the composite link, advanced multipath, the solution SHOULD define
a means to cause the LSPs for some traffic flows or groups of flows to move
to some other point in the network that is not congested.
These "preempted LSPs" flows" may not be restored if there is no
uncongested path in the network.

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
it if used in routing decisions it can result in routing instability.
This tradeoff is discussed in detail in
[I-D.ietf-rtgwg-cl-framework].

4.3.

3.3. Parallel Component Links with Different Characteristics

Corresponding to Case 1 of [ITU-T.G.800], as

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. When the path
for a flow can be chosen from a set of candidate nodes connected via composite links,
advanced multipaths, other techniques have been developed. Refer to
the Appendices in [I-D.ietf-rtgwg-cl-use-cases] for a description of
existing techniques and a set of references.

FR#11

FR#12 The solution SHALL measure traffic on a labeled flows or groups of traffic flow
flows and dynamically select the component link on which to
place this flow traffic in order to balance the load so that no
component link in the composite link advanced multipath between a pair of
nodes is overloaded.

FR#12

FR#13 When a traffic flow is moved from one component link to
another in the same composite link advanced multipath between a set of nodes
(or sites), it MUST be done so in a minimally disruptive
manner.

FR#13

FR#14 Load balancing MAY be used during sustained low traffic
periods to reduce the number of active component links for the
purpose of power reduction.

FR#14

FR#15 The solution SHALL provide a means to identify flows whose
rearrangement frequency needs to be bounded by a configured
value.

FR#15
value and MUST provide a means to bound the rearrangement
frequency for these flows.

FR#16 The solution SHALL provide a means that communicates whether
the flows within an client LSP can be split across multiple
component links. The solution SHOULD provide a means to
indicate the flow identification field(s) which can be used
along the flow path which can be used to perform this
function.

FR#16

FR#17 The solution SHALL provide a means to indicate that a traffic
flow shall select will traverse a component link with the minimum latency
value.

FR#17

FR#18 The solution SHALL provide a means to indicate that a traffic
flow shall select will traverse a component link with a maximum acceptable
latency value as specified by protocol.

FR#18

FR#19 The solution SHALL provide a means to indicate that a traffic
flow shall select will traverse a component link with a maximum acceptable
delay variation value as specified by protocol.

FR#19

FR#20 The solution SHALL provide a means local to a node that
automatically distributes flows across the component links in
the composite link advanced multipath such that NPOs Performance Objectives are met.

FR#20
met as described in prior requirements.

FR#21 The solution SHALL provide a means to distribute flows from a
single client LSP across multiple component links to handle at
least the case where the traffic carried in an client LSP
exceeds that of any component link in the composite link. advanced multipath.
As defined in
section 3, Section 2, a flow is a sequence of packets that must
should be transferred on one component link.

FR#21 link and should be
transferred in order.

FR#22 The solution SHOULD support the use case where a composite
link an advanced
multipath itself is a component link for a higher order composite
link.
advanced multipath. For example, a composite link an advanced multipath
comprised of MPLS-TP bi-
directional bi-directional tunnels viewed as logical
links could then be used as a component link in yet another composite link
advanced multipath that connects MPLS routers.

FR#22

FR#23 The solution MUST support an optional means for client LSP
signaling to bind an a client LSP to a particular component link
within a
composite link. an advanced multipath. If this option is not
exercised, then an a client LSP that is bound to a composite link an advanced
multipath may be bound to any component link matching all
other signaled requirements, and different directions of a
bidirectional client LSP can be bound to different component
links.

FR#23

FR#24 The solution MUST support a means to indicate that both
directions of co-routed bidirectional client LSP MUST be bound
to the same component link.

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 which 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, 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 an NPO. 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. The
network operator when configuring a network for power reduction
should weigh the benefit of power reduction against the disadvantage
of a minimal disruption.

4. Derived Requirements

This section takes the next step and derives high-level requirements
on protocol specification from the functional requirements.

DR#1 The solution SHOULD attempt to extend existing protocols
wherever possible, developing a new protocol only if this adds
a significant set of capabilities.

DR#2 A solution SHOULD extend LDP capabilities to meet functional
requirements (without using TE methods as decided in
[RFC3468]).

DR#3 Coexistence of LDP and RSVP-TE signaled LSPs MUST be supported
on a composite link. an advanced multipath. Other functional requirements should
be supported as independently of signaling protocol as
possible.

DR#4 When the nodes connected via a composite link an advanced multipath are in the
same MPLS network topology, the solution MAY define extensions
to the IGP.

DR#5 When the nodes are connected via a composite link an advanced multipath are in
different MPLS network topologies, the solution SHALL NOT rely
on extensions to the IGP.

DR#6 The solution SHOULD support composite link advanced multipath 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 also minimizes the
frequency of advertisement updates which 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, up/down
state), and/or bandwidth utilization.

DR#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 meet the NPO objective support protocol mechanisms meeting existing
provider Performance Objective for the duration of
unavailability. The
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 Management Plane MUST support polling of the status and
configuration of a composite link an advanced multipath and its individual composite
link
advanced multipath and support notification of status change.

MR#2 Management Plane MUST be able to activate or de-activate any
component link in a composite link an advanced multipath in order to facilitate
operation maintenance tasks. The routers at each end of a
composite link an
advanced multipath MUST redistribute traffic to move traffic
from a de-activated link to other component links based on the
traffic flow TE criteria.

MR#3 Management Plane MUST be able to configure a client LSP over a
composite link an
advanced multipath and be able to select a component link for
the client LSP.

MR#4 Management Plane MUST be able to trace which component link a
client LSP is assigned to and monitor individual component link
and
composite link advanced multipath performance.

MR#5 Management Plane MUST be able to verify connectivity over each
individual component link within a composite link. an advanced multipath.

MR#6 Component link fault notification MUST be sent to the
management plane.

MR#7 Composite link Advanced multipath fault notification MUST be sent to the
management plane and distribute MUST be distributed via link state message
in the IGP.

MR#8 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 4.3.

MR#10 Any statement which requires the solution to support some new
functionality through use of the words new functionality,
SHOULD be interpretted 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.

7. 3.3.

6. Acknowledgements

Frederic Jounay of France Telecom and Yuji Kamite of NTT
Communications Corporation co-authored a version of this document.

A rewrite of this document occurred after the IETF77 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 IETF77 RTGWG meeting.

Tony Li and John Drake have made numerous valuable comments on the
RTGWG mailing list that are reflected in versions following the
IETF77 meeting.

Iftekhar Hussain and Kireeti Kompella made comments on the RTGWG
mailing list after IETF82 that identified a new requirement.
Iftekhar Hussain made numerous valuable comments on the RTGWG mailing
list that resulted in improvements to document clarity.

In the interest of full disclosure of affiliation and in the interest
of acknowledging sponsorship, past affiliations of authors are noted.
Much of the work done by Ning So occurred while Ning was at Verizon.
Much of the work done by Curtis Villamizar occurred while at
Infinera. Infinera continues to sponsor this work on a consulting
basis.

Tom Yu and Francis Dupont provided the SecDir and GenArt reviews
respectively. Both reviews provided useful comments. Lou Berger
provided the RtgDir review which resulted in substantial
clarification of terminology and document wording, particularly in
the Abstract, Introduction, and Definitions sections.

7. IANA Considerations

This memo includes no request to IANA.

8. Security Considerations

This document specifies a set of requirements.

The requirements
themselves do not pose a security threat. If these requirements considerations for MPLS/GMPLS and for MPLS-TP are
met using MPLS signaling as commonly practiced today with
authenticated but unencrypted OSPF-TE, ISIS-TE,
documented in [RFC5920] and RSVP-TE or LDP,
then [RFC6941]. This document does not impact
the requirement to provide additional information in this
communication presents security of MPLS, GMPLS, or MPLS-TP.

The additional information that could conceivably
be gathered in a man-in-the-middle confidentiality breach. Such an
attack would require a capability to monitor this signaling either
through a provider breach or access document requires does not
provide significant additional value to provider physical transmission
infrastructure. A provider breach an attacker beyond the
information already poses typically available from attacking a threat of numerous
tpes routing or
signaling protocol. If the requirements of attacks which this document are met by
extending an existing routing or signaling protocol, the security
considerations of far more serious consequence. Encrption the protocol being extended apply. If the
requirements of this document are met by specifying a new protocol,
the signaling can prevent or render more difficult any
confidentiality breach security considerations of that otherwise might occur by means new protocol should include an
evaluation of access
to provider physical transmission infrastructure.

10. what level of protection is required by the additional
information specified in this document, such as data origin
authentication.

9. References

10.1.

9.1. Normative References

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.

10.2.

9.2. Informative References

[I-D.ietf-rtgwg-cl-framework]
Ning, S., McDysan, D., Osborne, E., Yong, L., and C.
Villamizar, "Composite Link Framework in Multi Protocol
Label Switching (MPLS)", draft-ietf-rtgwg-cl-framework-01
(work in progress), August 2012.

[I-D.ietf-rtgwg-cl-use-cases]
Ning, S., Malis, A., McDysan, D., Yong, L., and C.
Villamizar, "Composite Link Use Cases and Design
Considerations", draft-ietf-rtgwg-cl-use-cases-01 (work in
progress), August 2012.

[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", 2007, <http://www.itu.int/rec/T-REC-G/
recommendation.asp?parent=T-REC-G.800>.

[RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol
Label Switching Architecture", RFC 3031, January 2001.

[RFC3032] Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y.,
Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack
Encoding", RFC 3032, January 2001.

[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, December 2001.

[RFC3468] Andersson, L. and G. Swallow, "The Multiprotocol Label
Switching (MPLS) Working Group decision on MPLS signaling
protocols", RFC 3468, February 2003.

[RFC3985] Bryant, S. and P. Pate, "Pseudo Wire Emulation Edge-to-
Edge (PWE3) Architecture", RFC 3985, March 2005.

[RFC4031] Carugi, M. and D. McDysan, "Service Requirements for Layer
3 Provider Provisioned Virtual Private Networks (PPVPNs)",
RFC 4031, April 2005.

[RFC5036] Andersson, L., Minei, I.,

[RFC4201] Kompella, K., Rekhter, Y., and B. Thomas, "LDP
Specification", L. Berger, "Link Bundling
in MPLS Traffic Engineering (TE)", RFC 5036, 4201, October 2007.

[RFC5921] Bocci, M., Bryant, S., Frost, D., Levrau, 2005.

[RFC5920] Fang, L., and L.
Berger, "A "Security Framework for MPLS in Transport and GMPLS
Networks", RFC 5921, 5920, July 2010.

Appendix A. ITU-T G.800 Composite Link Definitions and Terminology

Composite Link:
Section 6.9.2 of ITU-T-G.800 [ITU-T.G.800] defines composite link
in terms of three cases, of which the following two are relevant
(the one describing inverse (TDM) multiplexing does not apply).
Note that these case definitions are taken verbatim from section
6.9, "Layer Relationships".

Case 1: "Multiple parallel links between the same subnetworks
can be bundled together into a single composite link. Each
component of the composite link is independent in the sense
that each component link is supported by a separate server
layer trail. The composite link conveys communication
information using different server layer trails thus the
sequence of symbols crossing this link may not be preserved.
This is illustrated in Figure 14."

Case 3: "A link can also be constructed by a concatenation of
component links and configured channel forwarding
relationships. The forwarding relationships must have a 1:1
correspondence to the link connections that will be provided
by the client link. In this case, it is not possible to
fully infer the status of the link by observing the server
layer trails visible at the ends of the link. This is
illustrated in Figure 16."

Subnetwork: A set of one or more nodes (i.e., LER or LSR)

[RFC6941] Fang, L., Niven-Jenkins, B., Mansfield, S., and links.
As a special case it can represent a site comprised of multiple
nodes.

Forwarding Relationship: Configured forwarding between ports on a
subnetwork. It may be connectionless (e.g., IP, not considered
in this draft), or connection oriented (e.g., MPLS signaled or
configured).

Component Link: A topolological relationship between subnetworks
(i.e., a connection between nodes), which may be a wavelength,
circuit, virtual circuit or an MPLS LSP. R.
Graveman, "MPLS Transport Profile (MPLS-TP) Security
Framework", RFC 6941, April 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 Malis
Verizon
60 Sylvan Road
Waltham, MA 02451
USA

Phone: +1 781-466-2362
Email: andrew.g.malis@verizon.com
Lucy Yong
Huawei USA
5340 Legacy Dr.
Plano, TX 75025
USA

Phone: +1 469-277-5837
Email: lucy.yong@huawei.com