wdiff draft-so-yong-mpls-ctg-framework-requirement-00.txt draft-so-yong-mpls-ctg-framework-requirement-01.txt

Network Working Group N. So
Internet-Draft A. Malis
Intended status: Standards Track D. McDysan
Expires: April 24, August 18, 2009 Verizon
L. Yong
Huawei USA
October 21, 2008
F. Jounay
France Telecom
February 14, 2009

Framework and Requirements for Composite Transport Group (CTG)
draft-so-yong-mpls-ctg-framework-requirement-00
draft-so-yong-mpls-ctg-framework-requirement-01

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Abstract

This document states a traffic distribution problem in today's IP/
MPLS network when multiple physical or logical links are configured
between two routers. The document presents a Composite Transport
Group framework as the
solution TE transport methodology over composite link for
the problems and specifies a set of requirements for Composite
Transport Group(CTG).

Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions used in this document . . . . . . . . . . . . . . 4
2.1. Acronyms . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2. Terminologies . . . . . . . . . . . . . . . . . . . . . . 4
3. Problem Statements . . . . . . . . . . . . . . . . . . . . . . 5 6
3.1. Incomplete/Inefficient Utilization . . . . . . . . . . . . 5 6
3.2. Inefficiency/Inflexibility of Logical Interface
Bandwidth Allocation . . . . . . . . . . . . . . . . . . . 6 7
4. Composite Transport Group Framework . . . . . . . . . . . . . 8 9
4.1. CTG Framework . . . . . . . . . . . . . . . . . . . . . . 8 9
4.2. Difference CTG Performance . . . . . . . . . . . . . . . . . . . . . 11
4.3. Differences between CTG and A Bundled Link Bundle . . . . . . . . 10
4.2.1. 12
4.3.1. Virtual Routable Link vs. TE Link . . . . . . . . . . 10
4.2.2. 12
4.3.2. Component Link Parameter Independence . . . . . . . . 11 13
5. Composite Transport Group Requirements . . . . . . . . . . . . 12 14
5.1. CTG Composite Link Appearance as a Routable Virtual
Interface . . . . . . 12 . . . . . . . . . . . . . . . . . . 14
5.2. CTG mapping of traffic Traffic Flows to Component Links . . . . . . . . 12 14
5.2.1. Mapping Using Router TE information . . . . . . . . . 12 15
5.2.2. Mapping When No Router TE Information is Available . . 12 15
5.3. Bandwidth Control for Connections with and without TE
information . . . . . . . . . . . . . . . . . . . . . . . 13 15
5.4. CTG Transport Resilience . . . . . . . . . . . . . . . . . 14 16
5.5. CTG Operational and Performance . . . . . . . . . . . . . 16
6. Security Considerations . . . . . . . . . . . . . . . . . . . 15 17
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16 18
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 17 19
9. Normative References . . . . . . . . . . . . . . . . . . . . . 18
Authors' Addresses . . . . . 20
9.1. Normative References . . . . . . . . . . . . . . . . . . . 19
Intellectual Property and Copyright Statements 20
9.2. Informative References . . . . . . . . . . . . . . . . . . 20
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 21

1. Introduction

IP/MPLS network traffic growth forces carriers to deploy multiple
parallel physical physical/logical links between two routers. The network is
also expected to carry some flows of a rate at rates that can approach that capacity
of any single link or link, and some flows to be very small comparing compared to a
single link rate. capacity. There is not an existing technology today that
allows carriers to efficiently utilize all parallel transport
resources in a complex IP/
MPLS IP/MPLS network environment. Composite
Transport Group (CTG) provides the local traffic engineering management
management/transport over multiple parallel links that solves this
problem in MPLS networks.

The primary function of Composite Transport Group is to efficiently
transport aggregated traffic flows over multiple parallel links. CTG
can take the flow TE information into account when distributing the
flows over individual links to gain local traffic engineering
management and link failure protection. Because all links have the
same ingress and egress point, CTG does not need to perform route
computation and forwarding based on the traffic unit end point
information, which brings allows for a unique local transport traffic
engineering scheme. CTG also manages the flows that do not have can transport both TE
information flows and associates them with non TE
flows. It maps the flows to CTG connections that have assigned TE
information either based on flow TE information or auto bandwidth measurement, and use
measurement on the connections. CTG distribution function uses CTG
connection TE information in the component link selection. selection that CTG
connections traverse over.

This document contains the problem statements and the framework and a
set of requirements for a Composite Transport Group (CTG). TE transport methodology over composite link.
The necessity for protcol protocol extensions to provide solutions is for
future study.

2. Conventions used in this document

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].

2.1. Acronyms

BW: BandWidth

CTG: Composite Transport Group

ECMP: Equal Cost Multi-Path

FRR: Fast Re-Route

LAG: Link Aggregation Group

LDP: Label Distributed Protocol

LR: Logical Router

LSP: Label Switched Path

MPLS: Multi-Protocol Label Switch Switching

OAM: Operation, Administration, and Maintenance

PDU: Packet Protocol Data Units Unit

PE: Provider Edge device

RSVP: ReSource reserVation Protocol

RTD: Real Time Delay

TE: Traffic engineering

VRF: Virtual Routing & Forwarding

2.2. Terminologies

Composite Link: a group of component links that acts as single
routable interface

Component Link: physical link (e.g. Lambda, Ethernet PHY, etc) or
logical links (e.g. LSP, etc)
Composite Transport Group (CTG): traffic engineered transport
function entity over composite link

CTG connection: a connection used for data plane

3. Problem Statements

Two applications are described here that encounter the problems when
multiple parallel links are deployed between two routers in today's
IP/MPLS networks.

3.1. Incomplete/Inefficient Utilization

An MPLS-TE network is deployed to carry traffic on RSVP-TE LSPs, i.e.
traffic engineered flows. When traffic volume exceeds the capacity
of a single physical link, multiple physical links are deployed
between two routers as a single backbone trunk. How to assign LSP
traffic over multiple links and maintain this backbone trunk as a
higher capacity and higher availability trunk than a single physical
link becomes an extremely difficult task for carriers today. Three
methods that are available today are described here.

1. A hashing method is a common practice for traffic distribution
over multiple paths. This is used by Equal Cost Multi-Path (ECMP) for IP services,
services and IEEE-defined Link Aggregation Group (LAG) for
Ethernet traffic. traffic are two of the widely deployed hashing based
technologies. However, two common occurrences in carrier
networks often prevent hashing being used efficiently. First,
for MPLS networks carrying mostly Virtual Private Network (VPN)
traffic, the incoming traffic are usually highly encrypted, so
that hashing depth is severely limited. Second, the traffic granularity in
a
an MPLS-TE network is individual LSPs, and they typically contain a high rate certain number of traffic flow(s) and
flows that have large vast differences in the
rates; furthermore, bandwidth requirements.
Furthermore, the links may be of different speeds. In
these those
cases hashing can cause some links to be congested while others
are partially filled because hashing can only distinguish the
flows, not the flow rates. A TE based solution better applies
for these cases. IETF has always had two technology tracks for
traffic distribution: TE-based and non-TE based. A TE based
solution provides a natural compliment to non-TE based hashing
methods.

2. Assigning individual LSPs to each link through constrained
routing. A planning tool can track the utilization of each link
and assignment of LSPs to the links. To gain high availability,
FRR [RFC4090] is used to create a bypass tunnel on a link to
protect traffic on another link or to create a detour LSP to
protect another LSP. If reserving BW for the bypass tunnels or
the detour LSPs, the network will reserve a large amount of
capacity for failure recovery, which reduces the capacity to
carry other traffic. If not reserving BW for the bypass tunnels
and the detour LSPs, the planning tool can not assign LSPs
properly to avoid the congestion during link failure when there
are more than two parallel links. This is because during the
link failure, the impacted traffic is simply put on a bypass
tunnel or detour LSPs which does not have enough reserved
bandwidth to carry the extra traffic during the failure recovery
phase.

3. Facility protection, also called 1:1 protection. Dedicate one
link to protect another link. Only assign traffic to one link in
the normal condition. When the working link fails, switch
traffic to the protected protection link. This requires 50% capacity for
failure recovery. This works when there are only two links.
Under the multiple parallel link condition, this causes
inefficient use of network capacity because there is no
protection capacity sharing. In addition, due to traffic
burstiness, having one link fully loaded and another link idle
increases transport latency and packet loss, which lowers the
link performance quality for transport.

None of these methods satisfies carrier requirement either because of
poor link utilization or poor performance. This forces carriers to
go with the solution of deploying single higher capacity link
solution. link.
However, a higher capacity link can be expensive as compared with
parallel low capacity links of equivalent aggregate capacity; a high
capacity link can not be deployed in some circumstances due to
physical impairments; or the highest capacity link may not large
enough for some carriers.

An LDP network can encounter the same issue as an MPLS-TE enabled
network when multiple parallel links are deployed as a backbone
trunk. An LDP network can have large variance in flow rates where,
for example, the small flows may be carrying stock tickers at a few
kbps per flow while the large flows can be near 10 Gbps per flow
carrying machine to machine and server to server traffic from
individual customers. Those large traffic flows often cannot be
broken into micro flows. Therefore, hashing would not work well for
the networks carrying such flows. Without per-flow TE information,
this type of network has even more difficulty to use multiple
parallel links and keep high link utilization.

3.2. Inefficiency/Inflexibility of Logical Interface Bandwidth
Allocation

Logically-separate routing instances in some implementations further
complicates the situation. Dedicating separate physical backbone
links to each routing instance is not efficient. An alternative is
to assign
links, or in the case of sharing of a logical interface and bandwidth on each single common link, dedicating
a portion of the parallel
physical links to each routing instance, which improves efficiency as
compared with dedicating physical links link, to each routing instance.
Inefficiency can result if bandwidth on a logical interface instance is
dedicated to each routing instance. not efficient.
For example, if there are 2 routing instances and 3 parallel links
and half of each link bandwidth is assigned to a routing instance,
then neither routing instance can support an LSP with bandwidth
greater than half the link bandwidth. The same problem is also
present in the case of sharing of a single common link using the
dedicated logical interface and link bandwidth method. An
alternative in dealing with multiple parallel links is to assign a
logical interface and bandwidth on each of the parallel physical
links to each routing instance, which improves efficiency as compared
to dedicating physical links to each routing instance.

Note that the traffic flows and LSPs from these different routing
instances effectively operate in a Ships-in-the-Night mode, where
they are unaware of each other. Inflexibility results if there are
multiple sets of LSPs (e.g., from different routing instances)
sharing one link or a set of parallel links, and at least one set of
LSPs can preempt another, others, then more efficient sharing of the link set
between the routing instances is highly desirable.

4. Composite Transport Group Framework

4.1. CTG Framework

Composite Transport Group (CTG) is the TE method to transport
aggregated traffic over a composite link. A composite link defined
in ITU-T [ITU-T G.800] is a single link that bundles multiple
parallel links between the two same subnetworks. Each of component links of link
in a composite link is independent in the sense that each component
link is supported by a separate server layer trail. trail that can be
implemented by different transport technologies such as wavelength,
Ethernet PHY, MPLS(-TP). The composite link conveys communication
information using different server layer trails thus the sequence of
symbols across this link may not be preserved.

Composite Transport Group (CTG) is primarily a local traffic
engineering and transport technology framework over multiple parallel links or
multiple paths. The objective is for a composite link to appear as a
virtual interface to the connected routers. The router provisions
incoming traffic over the virtual interface. CTG connection. creates CTG
connection and map incoming traffic CTG connections. CTG connections
are transported over parallel links, i.e. component links called Component Links. CTG
Component Links can be either physical links or logical links such as
LSP tunnels. in a
composite link. The CTG distribution function can locally determine
which component link CTG connections should traverse. traverse over. The major
components of CTG and their relationships are
framework is illustrated in Figure 1 below.

+---------+ +-----------+
| +---+ +---+ |
| | |============================| | |
LSP,LDP,IP|
LSP,LDP,IGP| | C |~~~~~~5 CTG Connections ~~~~| C | |
~~~|~~>~~| |============================| |~~~>~~~|~~~
~~~|~~>~~| T |============================| T |~~~>~~~|~~~
~~~|~~>~~| |~~~~~~3 CTG Connections ~~~~| |~~~>~~~|~~~
| | G |============================| G | |
| | |============================| | |
| | |~~~~~~9 CTG connections~~~~~| | |
| | |============================| | |
| R1 +---+ +---+ R2 |
+---------+ +-----------+
! ! ! !
! !<----Component Links ------>! !
!<------ Composite Link ----------->!

Figure 1: Composite Transport Group Architecture Model

In Figure 1, a composite link is configured between router R1 and R2.
The composite link has three component links. To transport LSP
traffic, CTG creates a CTG connection for the LSP first, and select a
component link for to carry the CTG connection. LSP,
LDP, (apply for LDP and IP IGP
traffic are mapped to CTG connections. as well). A CTG connection only exists in the scope of a
composite link. The traffic in a CTG connection is transported over
a single component link.

The model in Figure 1 applies two basic scenarios but is not limited
to. First, a set of physical links connect adjacent (P) routers.
Second, a set of logical links connect adjacent (P or PE) routers
over other equipment that may implement RSVP-TE signaled MPLS
tunnels, or MPLS-TP tunnels.

A CTG connection is a point-to-point logical connection over a
composite link. The connection rides on component link in a one-to-
one or many-to-one relationship. LSPs map to CTG connections in a
one-to-one or many-to-one relationship. The connection can have the
following traffic engineering parameters:

o bandwidth over-subscription

o factor placement

o priority

o holding priority

CTG connection TE parameters can be mapped directly from the LSP
parameters signaled in RSVP-TE or can be set at the CTG management
interface (CTG Logical Port). The connection bandwidth MUST shall be set.
If a LSP has no bandwidth information, the bandwidth will be
calculated at CTG ingress using automatic bandwidth measurement
function.

LDP LSPs can be mapped onto the connections per LDP label. Both
outer label (PE-PE label) and Inner label (VRF Label) can be used for
the connection mapping. CTG connection bandwidth MUST shall be set
through auto-bandwidth measurement function at the CTG ingress. When
the connection bandwidth tends to exceed the component link capacity,
CTG is able to reassign the flows in one connection into several
connections and assign other component links for the connections
without traffic disruption.

A CTG component link can be a physical link or logical link (LSP
Tunnel)
Tunnel [LSP Hierarchy]) between two routers. When component links
are physical links, there is no restriction to component link type,
bandwidth, and performance objectives (e.g., RTD and Jitter). Each
component link
MUST maintain maintains its own OAM. CTG is able to get component
link status from each link and take an action upon component link
status changes.

Each component link can have its own Component Link Cost and
Component Link Bandwidth as its associated engineered parameters.
CTG uses component link parameters in the assignment of CTG
connections to component links.

CTG provides local traffic engineering management over parallel links
based on CTG connection TE information and component link parameters.
Component link selection for CTG connections is determined locally
and may change without reconfiguring the traffic flows. Changing the
selection may be triggered by a component link condition change,
configuration of a new traffic flow configured or modification on existing one modified, one,
or operator required optimization process. CTG component link selection for The assignment of CTG
connections to component links enables TE based traffic distribution
and link failure recovery with much less link capacity than current
methods mentioned in the section of the problem statements.

CTG connections are created for traffic management purpose on a
composite link. They do not change the forwarding schema. The
forwarding engine still forwards based on the LSP label created per
traffic LSP. Therefore, there is no change to the forwarding.

Since MPLS is built on

CTG techniques applies to the situation that the top rate of IP network, some IP PDUs the distinct
traffic flows are
carried over not higher than the MPLS network. capacity of any component link
in composite link.

4.2. CTG may designate Performance

Packet re-ordering when moving a CTG connection from one component
link to another can occur when the new path is shorter than the
previous path and the interval between packet transmissions is less
than the difference in latency between the previous and the new
paths. If the new path is longer than the previous path, then re-
ordering will not occur, but the inter-packet delay variation will be
increased for those packets before and after the change from the
previous to the new path. Requirements are stated in this draft to
allow an operator to control the frequency of CTG path changes to
control the rate of occurrence for these reordering or inter-packet
delay variation events.

In order to prevent packet loss, CTG must employ make-before-break
when a connection to component link mapping change has to occur.
When CTG determines that the current component link for such the
connection is no longer sufficient based on the connection bandwidth
requirement, CTG ingress establishes a new connection with increased
bandwidth on the alternative component link, and switches the traffic
onto the new connection before the old connection is torn down. If
the new connection is placed on a link that has equal or use hashing longer
latency than the previous link, the packet re-ordering problem does
not occur, but inter-packet delay variation will increase for a pair
of packets. When a component link fails, CTG may also move some
impacted CTG connections to distribute IP PDUs over other component links. The assumption is In this case, a
short service disruption may occur, similar to that such caused by other
local protection methods.

Time sensitive traffic volume can be supported by CTG. For example, when
some traffic which is very small
compared sensitive to LSP latency (as indicated by pre-
set priority bits (i.e., DSCP or LDP traffic. Ethernet user priority) is being
carried over CTG techniques applies to the situation that the rate consists of component links that cannot support
the distinct traffic flows are not higher than latency requirement, the traffic flow with strict latency
requirement can be mapped onto certain component link capacity in CTG.

4.2. Difference links manually or by
using pre-defined policy setting at CTG ingress.

4.3. Differences between CTG and A Bundled Link

4.2.1. Bundle

4.3.1. Virtual Routable Link vs. TE Link

CTG is a data plan plane transport function over a composite link. A
composite link contains multiple component links that can carry
traffic independently. CTG is the method to transport aggregated
traffic over a composite link. The composite link appears as a
single routable virtual interface between the connected routers. The
component links in composite link do not belong to IGP links in OSPF/
IS-IS. The network only maps LSP or LDP to a composite link, i.e.
not to individual component links. CTG ingress will select component
link for individual LSP and LDP and merge them at composite link
egress. CTG ingress does not need to inform CTG egress which
component link CTG connections traverse over.

A bundled link bundle [RFC4201] is a collection of TE links. It is a logical
construct that represents a way to group/map the information about
certain physical resources that interconnect routers. The purpose of bundled
link bundle is to improve routing scalability by reducing the amount
of information that has to be handled by OSPF/IS-IS. Each physical
links in the bundled link bundle are an IGP link in OSPF/IS-IS. A
bundled link
bundle only has the significance to router control plane. The
router has to map individual
mapping of LSP to each component link in the
bundled link, which a bundle is different from CTG. determined at LSP
setup time and this mapping does not change due to new configurations
of LSP/LDP traffic. A bundled link bundle only applies to RSVP-TE signaled
traffic, CTG applies to RSVP/RSVP-TE/LDP signaled traffic.

4.2.2.

4.3.2. Component Link Parameter Independence

CTG allows component links to have different costs, traffic
engineering metric and resource classes. CTG can derive the virtual
interface cost from component link costs based on operator policy.
CTG can derive the traffic engineering parameter for a virtual
interface from its component link traffic engineering parameters.

However, a bundled link [RFC4201]

A Link Bundle requires that all component links in a bundle to have
the same traffic engineering metric, and the same set of resource
classes.

5. Composite Transport Group Requirements

Composite Transport Group (CTG) is about the method to transport
aggregated traffic over multiple parallel links. CTG can address the
problems existing in today IP/MPLS network. Here are some CTG
requirements:

5.1. CTG Composite Link Appearance as a Routable Virtual Interface

The carrier needs a solution where multiple routing instances see a
separate "virtual interface" to a shared composite transport group link composed of
parallel physical physical/logical links between a pair of routers.

The

CTG would communicate parameters (e.g., admin cost, available
bandwidth, maximum bandwidth, allowable bandwidth) for the "virtual
interface" associated with each routing instance.

The "virtual interface" shall appear as a fully-featured IP routing
adjacency
to in each routing instance, not just an FA [RFC3477] . In
particular, it needs to work with at least the following IP/MPLS
control protocols: IGP, OSPF/IS-IS, LDP, IGP-TE, and RSVP-TE.

CTG SHALL accept a new component link or remove an existing component
link by operator provisioning or in response to signaling at a lower
layer (e.g., using GMPLS).

CTG SHALL be able to derive the admin cost and TE metric of the
"virtual interface" from the admin cost and TE metric of individual
component links.

A component link in CTG SHALL be supportable numbered link or
unnumbered link in the IGP.

5.2. CTG mapping of traffic Traffic Flows to Component Links

The objective of CTG is to solve the traffic sharing problem at a
virtual interface level by mapping LSP traffic to component links
(not using hashing):

1. using TE information from the control planes of the routing
instances attached to the virtual interface when available, or

2. using traffic measurements when it is not.

CTG SHALL map traffic flows to CTG connections and place an entire
connection onto a single component link.

CTG SHALL support operator assignment of traffic flow to component
link.

5.2.1. Mapping Using Router TE information

CTG SHALL use RSVP-TE for bandwidth signaled by a routing instance to
explicitly assign a TE LSPs information to the CTG connection that is assigned to a
specific link in the CTG.

The LSP
is mapped to.

CTG SHALL be able to receive, interpret and act upon at least the
following router signaled parameters: minimum bandwidth, maximum
bandwidth, preemption priority, and holding priority and apply them
to the CTG connections where the LSP is mapped.

5.2.2. Mapping When No Router TE Information is Available

CTG SHALL map LDP-assigned labeled packets based upon local
configuration (e.g., label stack depth) to define a CTG connection
that is mapped to one of the parallel component links in the CTG between
routers. CTG.

CTG SHALL map LDP-assigned labeled packets that identify the source-
destination LER as a CTG connection to a specific link in the CTG. connection.

CTG SHALL also handle IP traffic without MPLS labels. This could use
locally defined methods SHOULD support entropy labels [Entropy Label] to assign sets of IP traffic map more
granular flows to a CTG
connection.

In all of the above mapping cases, CTG SHALL place an entire
connection onto a single physical link. connections.

In a mapping case, the CTG SHALL be able to measure the bandwidth
actually used by a particular connection to determine which component link
(physical link) on the CTG that CTG connection should be transmitted.

The CTG SHALL support parameters that control and derive proper TE
information for the time period between
moving a CTG connection from one link to another since this could
cause reordering.

The connection.

CTG SHALL support parameters that define at least a minimum
bandwidth, maximum bandwidth, preemption priority, and holding
priority for connections without TE information.

5.3. Bandwidth Control for Connections with and without TE information

The following requirements apply to a virtual interface (i.e.,
composite link in section 4) with CTG
capability that supports connections the traffic flows with TE information in conjunction with connections that do not have and
the flows without TE information.

A "bandwidth shortage" issue can arise in CTG if the total bandwidth
of the connections with provisioned TE information and those without with
auto measured TE information exceeds the bandwidth of the composite
link.

The

CTG SHALL support a policy based preemption capability such that that, in
the event of such a "bandwidth shortage" that shortage", the signaled or configured
preemption and holding parameters can be applied to the following
treatments to the connections:

o For a connection that has RSVP-TE LSP(s), signal the router that
the TE-LSP LSP has been preempted. CTG SHALL support soft preemption
(i.e., notify the preempted LSP source prior to preemption).
[Soft Preemption]

o For a connection that has LDP(s), where the CTG is aware of the
LDP signaling involved to the preempted label stack depth, signal
release of the label to the router

o For a connection that has IP traffic without MPLS labels, indicate
congestion to non-re-routable RSVP-TE LSP(s) or non-
releasable LDP(s), signal the router (e.g., using ECN, PCN, or some local
method) operator that the LSP or block IP traffic.
LDP has been lost.

5.4. CTG Transport Resilience

Component link links in CTG can may fail independently. The failure of a
component link can may impact some CTG connections. The impacted CTG
connection
connections SHALL be placed replaced to other active component links by
using the same rules as of the assignment of CTG connection to
component link.

CTG component link section recovery scheme SHALL perform equal to or better
than existing local recovery methods. A short service disruption may
occur during the recovery period.

5.5. CTG Operational and Performance

CTG requires methods to dampen the frequency of connection bandwidth
change and/or connection to component link mapping changes (e.g., for
re-optimization). Operator imposed control policy SHALL be allowed.

CTG connections. SHALL support latency sensitive traffic.

The determination of latency sensitive traffic SHALL be determined by
any of the following methods:

o Use of a pre-defined local policy setting at CTG ingress

o A manually configured setting at CTG ingress

o MPLS traffic class in a RSVP-TE signaling message

The determination of latency sensitive traffic SHOULD be determined
(if possible) by any of the following methods:

o Pre-set bits in the Payload (e.g., DSCP bits for IP or Ethernet
user priority for Ethernet payload)

6. Security Considerations

CTG is a local function on the router to support traffic engineering
management over multiple parallel links. It does not introduce a
security risk for control plane and dada data plane.

7. IANA Considerations

There is no

IANA actions requested in this specification. to provide solutions are for further study.

8. Acknowledgements

Authors would like to thank Frederic Jounay from France Telecom, Adrian Farrel from Olddog, and Ron Bonica
from Juniper Juniper, Nabil Bitar from Verizon, and Eric Gray from Ericsson
for the review and great suggestions.

9. References

9.1. Normative References

[ITU-T G.800]
ITU-T Q12, "Unified Functional Architecture of Transport
Network", ITU-T G.800, February 2008.

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

[RFC3477] Kompella, K., "Signalling Unnumbered Links in Resource
ReSerVation Protocol - Traffic Engineering (RSVP-TE)",
RFC 3477, January 2003.

[RFC4090] Pan, P., "Fast Reroute Extensions to RSVP-TE for LSP
Tunnels", RFC 4090, May 2005.

[RFC4201] Kompella, K., "Link Bundle in MPLS Traffic Engineering",
RFC 4201, March 2005.

9.2. Informative References

[Entropy Label]
Kompella, K. and S. Amante, "The Use of Entropy Labels in
MPLS Forwarding", November 2008, <http://www.ietf.org/
internet-drafts/draft-kompella-mpls-entropy-label-01>.

[LSP Hierarchy]
Shiomoto, K. and A. Farrel, "Procedures for Dynamically
Signaled Hierarchical Label Switched Paths",
November 2008, <http://www.ietf.org/internet-drafts/
draft-ietf-ccamp-lsp-hierarchy-bis-05.txt>.

[Soft Preemption]
Meyer, M. and J. Vasseur, "MPLS Traffic Engineering Soft
Preemption", February 2009, <http://www.ietf.org/
internet-drafts/draft-ietf-mpls-soft-preemption-16.txt>.

Authors' Addresses

So Ning
Verizon
2400 N. Glem Ave.,
Richerson, TX 75082

Phone: +1 972-729-7905
Email: ning.so@verizonbusness.com ning.so@verizonbusiness.com

Andrew Malis
Verizon
117 West St.
Waltham, MA 02451

Phone: +1 781-466-2362
Email: andrew.g.malis@verizon.com

Dave McDysan
Verizon
22001 Loudoun County PKWY
Ashburn, VA 20147

Phone: +1 707-886-1891
Email: dave.mcdysan@verizon.com

Lucy Yong
Huawei USA
1700 Alma Dr. Suite 500
Plano, TX 75075

Phone: +1 469-229-5387
Email: lucyyong@huawei.com

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Frederic Jounay
France Telecom
2, avenue Pierre-Marzin
22307 Lannion Cedex,
FRANCE

Phone:
Email: frederic.jounay@orange-ftgroup.com