MPLS Working Group M. Bocci, Ed.
Internet-Draft Alcatel-Lucent
Intended status: Standards Track S. Bryant, Ed.
Expires: December 31, 2009 Cisco Systems
L. Levrau
Alcatel-Lucent
June 29, 2009
A Framework for MPLS in Transport Networks
draft-ietf-mpls-tp-framework-01
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Abstract
This document specifies an archiectectural framework for the
application of MPLS in transport networks. It describes a profile of
MPLS that enables operational models typical in transport networks
networks, while providing additional OAM, survivability and other
maintenance functions not currently supported by MPLS.
Requirements Language
Although this document is not a protocol specification, 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 [RFC2119] and are to be
interpreted as instructions to the protocol designers producing
solutions that satisfy the architectural concepts set out in this
document..
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Motivation and Background . . . . . . . . . . . . . . . . 3
1.2. Applicability . . . . . . . . . . . . . . . . . . . . . . 4
1.3. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.4. Terminology . . . . . . . . . . . . . . . . . . . . . . . 6
2. Introduction to Requirements . . . . . . . . . . . . . . . . . 6
3. Transport Profile Overview . . . . . . . . . . . . . . . . . . 7
3.1. Packet Transport Services . . . . . . . . . . . . . . . . 7
3.2. Architecture . . . . . . . . . . . . . . . . . . . . . . . 7
3.3. MPLS-TP Forwarding Domain . . . . . . . . . . . . . . . . 10
3.4. MPLS-TP Transport Domain . . . . . . . . . . . . . . . . . 11
3.5. Addressing . . . . . . . . . . . . . . . . . . . . . . . . 11
3.6. Operations, Administration and Maintenance (OAM) . . . . . 13
3.7. Generic Associated Channel (G-ACh) . . . . . . . . . . . . 17
3.8. Control Plane . . . . . . . . . . . . . . . . . . . . . . 20
3.8.1. PW Control Plane . . . . . . . . . . . . . . . . . . . 22
3.8.2. LSP Control Plane . . . . . . . . . . . . . . . . . . 22
3.9. Static Operation of LSPs and PWs . . . . . . . . . . . . . 23
3.10. Survivability . . . . . . . . . . . . . . . . . . . . . . 23
3.11. Network Management . . . . . . . . . . . . . . . . . . . . 24
4. Security Considerations . . . . . . . . . . . . . . . . . . . 25
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 26
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 26
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 26
7.1. Normative References . . . . . . . . . . . . . . . . . . . 26
7.2. Informative References . . . . . . . . . . . . . . . . . . 29
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1. Introduction
1.1. Motivation and Background
This document describes a framework for a Multiprotocol Label
Switching Transport Profile (MPLS-TP). It presents the architectural
framework for MPLS-TP, definining those elements of MPLS applicable
to supporting the requirements in [I-D.ietf-mpls-tp-requirements] and
what new protocol elements are required.
Bandwidth demand continues to grow worldwide, stimulated by the
accelerating growth and penetration of new packet based services and
multimedia applications:
o Packet-based services such as Ethernet, Voice over IP (VoIP),
Layer 2 (L2)/Layer 3 (L3) Virtual Private Networks (VPNs), IP
Television (IPTV), Radio Access Network (RAN) backhauling, etc.,
o Applications with various bandwidth and Quality of Service (QoS)
requirements.
This growth in demand has resulted in dramatic increases in access
rates that are, in turn, driving dramatic increases in metro and core
network bandwidth requirements.
Over the past two decades, the evolving optical transport
infrastructure (Synchronous Optical Networking (SONET)/Synchronous
Digital Hierarchy (SDH), Optical Transport Network (OTN)) has
provided carriers with a high benchmark for reliability and
operational simplicity. To achieve this, these existing transport
technologies have been designed with specific characteristics :
o Strictly connection-oriented connectivity, which may be long-lived
and may be provisioned manually or by network management.
o A high level of protection and availability.
o Quality of service.
o Extended OAM capabilities.
Carriers are looking to evolve such transport networks to support
packet based services and networks, and to take advantage of the
flexibility and cost benefits of packet switching technology. While
MPLS is a maturing packet technology that is already playing an
important role in transport networks and services, not all of MPLS's
capabilities and mechanisms are needed and/or consistent with
transport network operations. There are also transport technology
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characteristics that are not currently reflected in MPLS.
The types of packet transport services delivered by transport
networks are very similar to Layer 2 Virtual Private Networks defined
by the IETF.
There are thus two objectives for MPLS-TP:
1. To enable MPLS to be deployed in a transport network and operated
in a similar manner to existing transport technologies.
2. To enable MPLS to support packet transport services with a
similar degree of predictability to that found in existing
transport networks.
In order to achieve these objectives, there is a need to create a
common set of new functions that are applicable to both MPLS networks
in general, and those blonging to the MPLS-TP profile.
MPLS-TP therefore defines a profile of MPLS targeted at transport
applications and networks. This profile specifies the specific MPLS
characteristics and extensions required to meet transport
requirements. An equipment conforming to MPLS-TP MUST support this
profile. An MPLS-TP conformant equipment MAY support additional MPLS
features. A carrier may deploy some of those additional features in
the transport layer of their network if they find them to be
beneficial.
1.2. Applicability
Figure 1 illustrates the range of services that MPLS-TP is intended
to address. MPLS-TP is intended to support a range of layer 1, layer
2 and layer 3 services, and is not limited to layer 3 services only.
Networks implementing MPLS-TP may choose to only support a subset of
these services.
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MPLS-TP Solution exists
over this spectrum
|<-------------------------------->|
cl-ps Multi-Service co-cs & co-ps
(cl-ps & co-ps) (Label is
| | service context)
| | |
|<------------------------------|--------------------------------->|
| | |
L3 Only L1, L2, L3 Services L1, L2 Services
Pt-Pt, Pt-MP, MP-MP Pt-Pt and Pt-MP
Figure 1: MPLS-TP Applicability
The diagram above shows the spectrum of services that can be
supported by MPLS. MPLS-TP solutions are primarily intended for
packet transport applications. These can be deployed using a profile
of MPLS that is strictly connection oriented and does not rely on IP
forwarding or routing (shown on the right hand side of the figure),
or in conjunction with an MPLS network that does use IP forwarding
and that supports a broader range of IP services. This is the multi-
service solution in the centre of the figure.
1.3. Scope
This document describes a framework for a Tranport Profile of
Multiprotocol Label Switching (MPLS-TP). It presents the
architectural framework for MPLS-TP, definining those elements of
MPLS applicable to supporting the requirements in
[I-D.ietf-mpls-tp-requirements] and what new protocol elements are
required.
This document describes the architecture for MPLS-TP when the LSP
client is a PW. The transport of IP and MPLS, other than carried
over a PW, is outside the scope of this document. This does not
preclude the use of LSPs conforming to the MPLS transport profile
from being used to carry IP or other MPLS LSPs by general purpose
MPLS networks.
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1.4. Terminology
Term Definition
------- -----------------------------------------
LSP Label Switched Path
MPLS-TP MPLS Transport profile
SDH Synchronous Digital Hierarchy
ATM Asynchronous Transfer Mode
OTN Optical Transport Network
cl-ps Connectionless - Packet Switched
co-cs Connection Oriented - Circuit Switched
co-ps Connection Oriented - Packet Switched
OAM Operations, Adminitration and Maintenance
G-ACh Generic Associated Channel
GAL Generic Alert Label
MEP Maintenance End Point
MIP Maintenance Intermediate Point
APS Automatic Protection Switching
SCC Signaling Communication Channel
MCC Management Communication Channel
EMF Equipment Management Function
FM Fault Management
CM Configuration Management
PM Performance Management
Detailed definitions and additional terminology may be found in
[I-D.ietf-mpls-tp-requirements].
2. Introduction to Requirements
The requirements for MPLS-TP are specified in
[I-D.ietf-mpls-tp-requirements], [I-D.ietf-mpls-tp-oam-requirements],
and [I-D.ietf-mpls-tp-nm-req]. This section provides a brief
reminder to guide the reader. It is not intended as a substitute for
these documents.
MPLS-TP MUST NOT modify the MPLS forwarding architecture and MUST be
based on existing pseudowire and LSP constructs. Any new mechanisms
and capabilities added to support transport networks and packet
transport services must be able to interoperate with existing MPLS
and pseudowire control and forwarding planes.
Point to point LSPs MAY be unidirectional or bi-directional, and it
MUST be possible to construct congruent Bi-directional LSPs. Point
to multipoint LSPs are unidirectional.
MPLS-TP LSPs do not merge with other LSPs at an MPLS-TP LSR and it
MUST be possible to detect if a merged LSP has been created.
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It MUST be possible to forward packets solely based on switching the
MPLS or PW label. It MUST also be possible to establish and maintain
LSPs and/or pseudowires both in the absence or presence of a dynamic
control plane. When static provisioning is used, there MUST be no
dependency on dynamic routing or signaling.
OAM, protection and forwarding of data packets MUST be able to
operate without IP forwarding support.
It MUST be possible to monitor LSPs and pseudowires through the use
of OAM in the absence of control plane or routing functions. In this
case information gained from the OAM functions is used to initiate
path recovery actions at either the PW or LSP layers.
3. Transport Profile Overview
3.1. Packet Transport Services
The types of packet transport services provided by existing transport
networks are similar to MPLS Layer 2 VPNs. A key characteristic of
packet transport services is that the network used to provide the
service does not participate in the any IP routing protocols present
in the client, or use the IP addresses in client packets to forward
those packets. The network is therefore transparent to IP in the
client service.
MPLS-TP MUST use one of the Layer 2 VPN services defined in [PPVPN
architecture] to provide a packet transport service.
MPLS-TP LSPs MAY also be used to transport traffic for which the
immediate client of the MPLS-TP LSP is not a Layer 2 VPN. However,
for the purposes of this document, we do not refer to these traffic
types as belonging to a packet transport service. Such clients
include IP and MPLS LSPs.
3.2. Architecture
The architecture for a transport profile of MPLS (MPLS-TP) is based
on the MPLS [RFC3031], pseudowire [RFC3985], and multi-segment
pseudowire [I-D.ietf-pwe3-ms-pw-arch] architectures, as illustrated
in Figure 2.
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|<-------------- Emulated Service ---------------->|
| |
| |<------- Pseudo Wire ------>| |
| | | |
| | |<-- PSN Tunnel -->| | |
| V V V V |
V AC +----+ +----+ AC V
+-----+ | | PE1|==================| PE2| | +-----+
| |----------|............PW1.............|----------| |
| CE1 | | | | | | | | CE2 |
| |----------|............PW2.............|----------| |
+-----+ ^ | | |==================| | | ^ +-----+
^ | +----+ +----+ | | ^
| | Provider Edge 1 Provider Edge 2 | |
| | | |
Customer | | Customer
Edge 1 | | Edge 2
| |
| |
Native service Native service
Figure 2: MPLS-TP Architecture (Single Segment PW)
Native |<------------Pseudowire-------------->| Native
Service | PSN PSN | Service
(AC) | |<--cloud->| |<-cloud-->| | (AC)
| V V V V V V |
| +----+ +-----+ +----+ |
+----+ | |TPE1|===========|SPE1 |==========|TPE2| | +----+
| |------|..... PW.Seg't1.........PW.Seg't3.....|-------| |
| CE1| | | | | | | | | |CE2 |
| |------|..... PW.Seg't2.........PW.Seg't4.....|-------| |
+----+ | | |===========| |==========| | | +----+
^ +----+ ^ +-----+ ^ +----+ ^
| | | |
| TE LSP TE LSP |
| |
| |
|<---------------- Emulated Service ----------------->|
MPLS-TP Architecture (Multi-Segment PW)
The above figures illustrates the MPLS-TP architecture used to
provide a point-to-point packet transport service, or VPWS. In this
case, the MPLS-TP forwarding plane is a profile of the MPLS LSP and
SS-PW or MS-PW forwarding architecture as detailed in section
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Section 3.3.
This document describes the architecture for MPLS-TP when the LSP
client is a PW. The transport of IP and MPLS, other than carried
over a PW, is outside the scope of this document. This does not
preclude the use of LSPs conforming to the MPLS transport profile
from being used to carry IP or other MPLS LSPs by general purpose
MPLS networks. LSP hierarchy MAY be used within the MPLS-TP network,
so that more than one LSP label MAY appear in the label stack.
+---------------------------+
| PW Native service |
/===========================\
H PW Encapsulation H \ <---- PW Control word
H---------------------------H \ <---- Normalised client
H PW OAM H MPLS-TP channel
H---------------------------H /
H PW Demux (S=1) H /
H---------------------------H \
H LSP OAM H \
H---------------------------H / MPLS-TP Path(s)
H LSP Demultiplexer(s) H /
\===========================/
| Server |
+---------------------------+
Figure 3: Domain of MPLS-TP Layer Network using Pseudowires
Figure (Figure 3) illustrates the protocol stack to be used when
pseudowires are carried over MPLS-TP LSPs.
When providing a VPWS, VPLS, VPMS or IPLS, pseudowires MUST be used
to carry a client service. For compatibility with transport
nomenclature, the PW may be referred to as the MPLS-TP Channel and
the LSP may be referred to as the MPLS-TP Path.
Note that in MPLS-TP environments where IP is used for control or OAM
purposes, IP MAY be carried over the LSP demultiplexers as per
RFC3031 [RFC3031], or directly over the server.
PW OAM, PSN OAM and PW client data are mutually exclusive and never
exist in the same packet.
The MPLS-TP definition applies to the following two domains:
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o MPLS-TP Forwarding Domain
o MPLS-TP Transport Domain
3.3. MPLS-TP Forwarding Domain
A set of client-to-MPLS-TP adaptation functions interface the client
to MPLS-TP. For pseudowires, this adaptation function is the PW
forwarder shown in Figure 4a of [RFC3985]. The PW label is used for
forwarding in this case and is always at the bottom of the label
stack. The operation of the MPLS-TP network is independent of the
payload carried by the MPLS-TP PW packet.
MPLS-TP is itself a client of an underlying server layer. MPLS-TP is
thus bounded by a set of adaptation functions to this server layer
network. These adaptation functions provide encapsulation of the
MPLS-TP frames and for the transparent transport of those frames over
the server layer network. The MPLS-TP client inherits its QoS from
the MPLS-TP network, which in turn inherits its QoS from the server
layer. The server layer must therefore provide the neccesary Quality
of Service (QoS) to ensure that the MPLS-TP client QoS commitments
are satisfied.
MPLS-TP LSPs use the MPLS label switching operations defined in
[RFC3031]. These operations are highly optimized for performance and
are not modified by the MPLS-TP profile.
During forwarding a label is pushed to associate a forwarding
equivalence class (FEC) with the LSP or PW. This specifies the
processing operaton to be performed by the next hop at that level of
encapsulation. A swap of this label is an atomic operation in which
the contents of the packet after the swapped label are opaque to the
forwarder. The only event that interrupts a swap operation is TTL
expiry, in which case the packet may be inspected and either
discarded or subjected to further processing within the LSR. TTL
expiry causes an exception which forces a packet to be further
inspected and processed. While this occurs, the forwarding of
succeeding packets continues without interruption. Therefore, the
only way to cause a P (intermediate) LSR to inspect a packet (for
example for OAM purposes) is to set the TTL to expire at that LSR.
MPLS-TP PWs support the PW and MS-PW forwarding operations defined
in[RFC3985] and [I-D.ietf-pwe3-ms-pw-arch].
The Traffic Class field (formerly the MPLS EXP field) follows the
definition and processing rules of [RFC5462] and [RFC3270]. Only the
pipe and short-pipe models are supported in MPLS-TP.
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The MPLS encapsulation format is as defined in RFC 3032[RFC3032].
Per-platform label space is used for PWs. Either per-platform or
per-interface label space may be used for LSPs.
Point to point MPLS-TP LSPs can be either unidirectional or
bidirectional. Point-to-multipoint MPLS-TP LSPs are unidirectional.
Point-to-multipont PWs are currently being defined in the IETF and
may be incorporated in MPLS-TP if required.
It MUST be possible to configure an MPLS-TP LSP such that the forward
and backward directions of a bidirectional MPLS-TP LSP are co-routed
i.e. they follow the same path. The pairing relationship between the
forward and the backward directions must be known at each LSR or LER
on a bidirectional LSP.
Per-packet equal cost multi-path (ECMP) load balancing is not
applicable to MPLS-TP LSPs.
Penultimate hop popping (PHP) is disabled on MPLS-TP LSPs by default.
Both E-LSP and L-LSP are supported in MPLS-TP, as defined in RFC 3270
[RFC3270]
3.4. MPLS-TP Transport Domain
This document specifies the architecture when the client of the
MPLS-TP LSP is a PW. Note, however, that in MPLS-TP environments
where IP is used for control or OAM purposes, IP MAY be carried over
the the LSPs or directly over the server, as described in
Section 3.2. In this case, the MPLS-TP transport domain consists of
the PW encapsulation mechanisms, including the PW control word.
3.5. Addressing
Editor's note: This section will be updated after publication of the
MPLS-TP Addressing Architecture draft.
MPLS-TP distinguishes between adressing used to identify nodes in the
network, and identifiers used for demultiplexing and forwarding.
This distinction is illustrated in Figure 4.
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NMS Control/Signalling
..... .....
[Address]| | [Address]
| |
+-----+---------+------+
Address = Node | | | |
ID in forwarding plane | V V |
| |
| MEP or MIP |
| dmux |
| svcid |
| src |
+--^-------------------+
|
OAM: OAM |
dmux= [GAL/GACH]...........
or ________________________________________
IP (________________________________________)
svc context=ID/FEC PWE=ID1
SRC=IP .
.
IDx
Figure 4: Addressing in MPLS-TP
Editor's note: The figure above arose from discussions in the MPLS-TP
design team. It will be clarified in a future verson of this draft.
IPv4 or IPv6 addresses are used to identify MPLS-TP nodes by default
for network management and signaling purposes.
In the forwarding plane, identfiers are required for the service
context (provided by the FEC), and for OAM. OAM requires both a
demultiplexer and an address for the source of the OAM packet.
For MPLS in general where IP addressing is used, IPv4 or IPv6 is used
by default. However, MPLS-TP must be able to operate in environments
where IP is not used in the forwarding plane. Therefore, the default
mechanism for OAM demultiplexing in MPLS-TP LSPs and PWs is the
generic associated channel. Forwarding based on IP addresses for
user or OAM packets is NOT REQUIRED for MPLS-TP.
RFC 4379 [RFC4379]and BFD for MPLS LSPs [I-D.ietf-bfd-mpls] have
defined alert mechanisms that enable a MPLS LSR to identify and
process MPLS OAM packets when the OAM packets are encapsulated in an
IP header. These alert mechanisms are based on TTL expiration and/or
use an IP destination address in the range 127/8. These mechanisms
are the default mechanisms for MPLS networks in general for
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identifying MPLS OAM packets when the OAM packets are encapsulated in
an IP header. MPLS-TP must not rely on these mechanisms, and thus
relies on the GACH/GAL to demultiplex OAM packets.
3.6. Operations, Administration and Maintenance (OAM)
MPLS-TP supports a comprehensive set of OAM capabilities for packet
transport applications, with equivalent capabilities to those
provided in SONET/SDH.
MPLS-TP defines mechanisms to differentiate specific packets (e.g.
OAM, APS, MCC or SCC) from those carrying user data packets on the
same LSP. These mechanisms are described in RFC5586 [RFC5586].
MPLS-TP requires [I-D.ietf-mpls-tp-oam-requirements] that a set of
OAM capabilities is available to perform fault management (e.g. fault
detection and localization) and performance monitoring (e.g. packet
delay and loss measurement) of the LSP, PW or section. The framework
for OAM in MPLS-TP is specified in [I-D.ietf-mpls-tp-oam-framework].
OAM and monitoring in MPLS-TP is based on the concept of maintenance
entities, as described in [I-D.ietf-mpls-tp-oam-framework]. A
Maintenance Entity can be viewed as the association of two (or more)
Maintenance End Points (MEPs) (see example in Figure 5 ). The MEPs
that form an ME should be configured and managed to limit the OAM
responsibilities of an OAM flow within a network or sub- network, or
a transport path or segment, in the specific layer network that is
being monitored and managed.
Each OAM flow is associated with a single ME. Each MEP within an ME
resides at the boundaries of that ME. An ME may also include a set
of zero or more Maintenance Intermediate Points (MIPs), which reside
within the Maintenance Entity. Maintenance end points (MEPs) are
capable of sourcing and sinking OAM flows, while maintenance
intermediate points (MIPs) can only sink or respond to OAM flows.
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========================== End to End LSP OAM ============================
..... ..... ..... .....
-----|MIP|---------------------|MIP|---------|MIP|------------|MIP|-----
''''' ''''' ''''' '''''
|<-------- Carrier 1 --------->| |<--- Carrier 2 ----->|
---- --- --- ---- ---- --- ----
NNI | | | | | | | | NNI | | | | | | NNI
-----| PE |---| P |---| P |----| PE |--------| PE |---| P |---| PE |-----
| | | | | | | | | | | | | |
---- --- --- ---- ---- --- ----
==== Segment LSP OAM ====== == Seg't == === Seg't LSP OAM ===
(Carrier 1) LSP OAM (Carrier 2)
(inter-carrier)
..... ..... ..... .......... .......... ..... .....
|MEP|---|MIP|---|MIP|--|MEP||MEP|---|MEP||MEP|--|MIP|----|MEP|
''''' ''''' ''''' '''''''''' '''''''''' ''''' '''''
<------------ ME ----------><--- ME ----><------- ME -------->
Note: MEPs for End-to-end LSP OAM exist outside of the scope of this figure.
Figure 5: Example of MPLS-TP OAM
Figure 6 illustrates how the concept of Maintenance Entities can be
mapped to sections, LSPs and PWs in an MPLS-TP network that uses MS-
PWs.
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Native |<-------------------- PW15 --------------------->| Native
Layer | | Layer
Service | |<-PSN13->| |<-PSN3X->| |<-PSNXZ->| | Service
(AC1) V V LSP V V LSP V V LSP V V (AC2)
+----+ +-+ +----+ +----+ +-+ +----+
+---+ |TPE1| | | |SPE3| |SPEX| | | |TPEZ| +---+
| | | |=========| |=========| |=========| | | |
|CE1|--------|........PW1........|...PW3...|........PW5........|-----|CE2|
| | | |=========| |=========| |=========| | | |
+---+ | 1 | |2| | 3 | | X | |Y| | Z | +---+
+----+ +-+ +----+ +----+ +-+ +----+
|<- Subnetwork 123->| |<- Subnetwork XYZ->|
.------------------- PW15 PME -------------------.
.---- PW1 PTCME ----. .---- PW5 PTCME ---.
.---------. .---------.
PSN13 LME PSNXZ LME
.--. .--. .--------. .--. .--.
Sec12 SME Sec23 SME Sec3X SME SecXY SME SecYZ SME
TPE1: Terminating Provider Edge 1 SPE2: Switching Provider Edge 3
TPEX: Terminating Provider Edge X SPEZ: Switching Provider Edge Z
.---. ME . MEP ==== LSP .... PW
SME: Section Maintenance Entity
LME: LSP Maintenance Entity
PME: PW Maintenance Entity
Figure 6: MPLS-TP OAM archtecture
The following MPLS-TP MEs are specified in
[I-D.ietf-mpls-tp-oam-framework]:
o A Section Maintenance Entity (SME), allowing monitoring and
management of MPLS-TP Sections (between MPLS LSRs).
o A LSP Maintenance Entity (LME), allowing monitoring and management
of an end-to-end LSP (between LERs).
o A PW Maintenance Entity (PME), allowing monitoring and management
of an end-to-end SS/MS-PWs (between T-PEs).
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o An LSP Tandem Connection Maintenance Entity (LTCME), allowing
monitoring and management of an LSP Tandem Connection (or LSP
Segment) between any LER/LSR along the LSP. o A MS-PW Tandem
Connection Maintenance Entity (PTCME), allows monitoring and
management of a SS/MS-PW Tandem Connection (or PW Segment) between
any T-PE/S-PE along the (MS-)PW. Note that the term Tandem
Connection Monitoring has historical significance dating back to
the early days of the telephone network, but is equally applicable
to the two-level hierarchal architectures commonly employed in
todays packet networks.
Individual MIPs along the path of an LSP or PW are addressed by
setting the appropriate TTL in the label for the OAM packet, as per
[I-D.ietf-pwe3-segmented-pw]. Note that this works when the location
of MIPs along the LSP or PW path is known by the MEP. There may be
cases where this is not the case in general MPLS networks e.g.
following restoration using a facility bypass LSP.
MPLS-TP OAM packets share the same fate as their corresponding data
packets, and are identified through the Generic Associated Channel
mechanism [RFC5586]. This uses a combination of an Associated
Channel Header (ACH) and a Generic Alert Label (GAL) to create a
control channel associated to an LSP, Section or PW.
The MPLS-TP OAM architecture support a wide range of OAM functions,
including the following
o Continuity Check
o Connectivity Verification
o Performance monitoring (e.g. loss and delay)
o Alarm suppression
o Remote Integrity
These are applicable to any layer defined within MPLS- TP, i.e. MPLS
Section, LSP and PW.
The MPLS-TP OAM toolset needs to be able to operate without relying
on a dynamic control plane or IP functionality in the datapath. In
the case of MPLS-TP deployment with IP functionality, all existing
IP-MPLS OAM functions, e.g. LSP-Ping, BFD and VCCV, may be used.
This does not preculde the use of other OAM tools in an IP
addressable network.
One use of OAM mechanisms is to detect link failures, node failures
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and performance outside the required specification which then may be
used to trigger recovery actions, according to the requirements of
the service.
3.7. Generic Associated Channel (G-ACh)
For correct operation of the OAM it is important that the OAM packets
fate share with the data packets. In addition in MPSL-TP it is
necessary to discriminate between user data payloads and other types
of payload. For example the packet may contain a Signaling
Communication Channel (SCC), or a channel used for Automatic
Protecton Switching (APS) data. Such packetets are carried on a
control channel associated to the LSP, Section or PW. This is
achieved by carrying such packets on a generic control channel
associated to the LSP, PW or section.
MPLS-TP makes use of such a generic associated channel (G-ACh) to
support Fault, Configuration, Accounting, Performance and Security
(FCAPS) functions by carrying packets related to OAM, APS, SCC, MCC
or other packet types in band over LSPs or PWs. The G-ACH is defined
in [RFC5586]and it is similar to the Pseudowire Associated Channel
[RFC4385], which is used to carry OAM packets across pseudowires.
The G-ACH is indicated by a generic associated channel header (ACH),
similar to the Pseudowire VCCV control word, and this is present for
all Sections, LSPs and PWs making use of FCAPS functions supported by
the G-ACH.
For pseudowires, the G-ACh use the first nibble of the pseudowire
control word to provide the initial discrimination between data
packets a packets belonging to the associated channel, as described
in[RFC4385]. When the first nibble of a packet, immediately
following the label at the bottom of stack, has a value of one, then
this packet belongs to a G-ACh. The first 32 bits following the
bottom of stack label then have a defined format called an associated
channel header (ACH), which further defines the content of the
packet. The ACH is therefore both a demultiplexer for G-ACh traffic
on the PW, and a discriminator for the type of G-ACh traffic.
When the OAM, or a similar message is carried over an LSP, rather
than over a pseudowire, it is necessary to provide an indication in
the packet that the payload is something other than a user data
packet. This is acheived by including a reserved label with a value
of 13 in the label stack. This reserved label is referred to as the
'Generic Alert Label (GAL)', and is defined in [RFC5586]. When a GAL
is found anywhere within the label stack it indicates that the
payload begins with an ACH. The GAL is thus a demultiplexer for
G-ACh traffic on the LSP, and the ACH is a discriminator for the type
of traffic carried on the G-ACh. Note however that MPLS-TP
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forwarding follows the normal MPLS model, and that a GAL is invisible
to an LSR unless it is the top label iin the label stack. The only
other circumstance under which the label stack may be inspected for a
GAL is when the TTL has expired. Any MPLS-TP component that
intentionally performs this inspection must assume that it is
asynchronous with respect to the forwarding of other packets. All
operations on the label stack arein accordance with [RFC3031] and
[RFC3032].
In MPLS-TP, the 'Generic Alert Label (GAL)' always appears at the
bottom of the label stack (i.e. S bit set to 1), however this does
not preclude its use elsewhere in the label stack in other
applications.
The G-ACH MUST only be used for channels that are an adjunct to the
data service. Examples of these are OAM, APS, MCC and SCC, but the
use is not resticted to those names services. The G-ACH MUST NOT be
used to carry additional data for use in the forwarding path, i.e. it
MUST NOT be used as an alternative to a PW control word, or to define
a PW type.
Since the G-ACh traffic is indistinguishable from the user data
traffic at the server layer, bandwidth and QoS commitments apply to
the gross traffic on the LSP, PW or section. Protocols using the
G-ACh must therefore take into consideration the impact they have on
the user data that they are sharing resources with. In addition,
protocols using the G-ACh MUST conform to the security and congestion
considerations described in [RFC5586]. .
Figure 7 shows the reference model depicting how the control channel
is associated with the pseudowire protocol stack. This is based on
the reference model for VCCV shown in Figure 2 of [RFC5085].
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+-------------+ +-------------+
| Payload | < Service / FCAPS > | Payload |
+-------------+ +-------------+
| Demux / | < CW / ACH for PWs > | Demux / |
|Discriminator| |Discriminator|
+-------------+ +-------------+
| PW | < PW > | PW |
+-------------+ +-------------+
| PSN | < LSP > | PSN |
+-------------+ +-------------+
| Physical | | Physical |
+-----+-------+ +-----+-------+
| |
| ____ ___ ____ |
| _/ \___/ \ _/ \__ |
| / \__/ \_ |
| / \ |
+--------| MPLS/MPLS-TP Network |---+
\ /
\ ___ ___ __ _/
\_/ \____/ \___/ \____/
Figure 7: PWE3 Protocol Stack Reference Model including the G-ACh
PW associated channel messages are encapsulated using the PWE3
encapsulation, so that they are handled and processed in the same
manner (or in some cases, an analogous manner) as the PW PDUs for
which they provide a control channel.
Figure 8 shows the reference model depicting how the control channel
is associated with the LSP protocol stack.
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+-------------+ +-------------+
| Payload | < Service > | Payload |
+-------------+ +-------------+
|Discriminator| < ACH on LSP > |Discriminator|
+-------------+ +-------------+
|Demultiplexer| < GAL on LSP > |Demultiplexer|
+-------------+ +-------------+
| PSN | < LSP > | PSN |
+-------------+ +-------------+
| Physical | | Physical |
+-----+-------+ +-----+-------+
| |
| ____ ___ ____ |
| _/ \___/ \ _/ \__ |
| / \__/ \_ |
| / \ |
+--------| MPLS/MPLS-TP Network |---+
\ /
\ ___ ___ __ _/
\_/ \____/ \___/ \____/
Figure 8: MPLS Protocol Stack Reference Model including the LSP
Associated Control Channel
3.8. Control Plane
MPLS-TP should be capable of being operated with centralized Network
Management Systems (NMS). The NMS may be supported by a distributed
control plane, but MPLS-TP can operated in the absense of such a
control plane. A distributed control plane may be used to enable
dynamic service provisioning in multi-vendor and multi-domain
environments using standardized protocols that guarantee
interoperability. Where the requirements specified in
[I-D.ietf-mpls-tp-requirements] can be met, the MPLS transport
profile uses existing control plane protocols for LSPs and PWs.
Figure 9 illustrates the relationshop between the MPLS-TP control
plane, the forwarding plane, the management plane, and OAM for point-
to-point MPLS-TP LSPs or PWs.
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+------------------------------------------------------------------------+
| |
| Network Management System and/or |
| |
| Control Plane for Point to Point Connections |
| |
+------------------------------------------------------------------------+
| | | | | |
............|......|..... ....|.......|.... ....|....|...............
+---+ | : : +---+ | : : +---+ | :
: |OAM| | : : |OAM| | : : |OAM| | :
: +---+ | : : +---+ | : : +---+ | :
: | | : : | | : : | | :
\: +----+ +----------+ : : +----------+ : : +----------+ +----+ :/
--+-|Edge|<->|Forwarding|<---->|Forwarding|<----->|Forwarding|<->|Edge|-+--
/: +----+ | | : : | | : : | | +----+ :\
: +----------+ : : +----------+ : : +----------+ :
''''''''''''''''''''''''' ''''''''''''''''' ''''''''''''''''''''''''
Note:
1) NMS may be centralised or distributed. Control plane is distributed
2) 'Edge' functions refers to those functions present at the edge of
a PSN domain, e.g. NSP or classification.
Figure 9: MPLS-TP Control Plane Architecture Context
The MPLS-TP control plane is based on a combination of the LDP-based
control plane for pseudowires [RFC4447] and the RSVP-TE based control
plane for MPLS-TP LSPs [RFC3471]. Some of the RSVP-TE functions that
are required for LSP signaling for MPLS-TP are based on GMPLS.
The distributed MPLS-TP control plane provides the following
functions:
o Signaling
o Routing
o Traffic engineering and constraint-based path computation
In a multi-domain environment, the MPLS-TP control plane supports
different types of interfaces at domain boundaries or within the
domains. These include the User-Network Interface (UNI), Internal
Network Node Interface (I-NNI), and External Network Node Interface
(E-NNI). Note that different policies may be defined that control
the information exchanged across these interface types.
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The MPLS-TP control plane is capable of activating MPLS-TP OAM
functions as described in the OAM section of this document
Section 3.6 e.g. for fault detection and localization in the event of
a failure in order to efficiently restore failed transport paths.
The MPLS-TP control plane supports all MPLS-TP data plane
connectivity patterns that are needed for establishing transport
paths including protected paths as described in the survivability
section Section 3.10 of this document. Examples of the MPLS-TP data
plane connectivity patterns are LSPs utilizing the fast reroute
backup methods as defined in [RFC4090] and ingress-to-egress 1+1 or
1:1 protected LSPs.
The MPLS-TP control plane provides functions to ensure its own
survivability and to enable it to recover gracefully from failures
and degredations. These include graceful restart and hot redundant
configurations. Depending on how the control plane is transported,
varying degrees of decoupling between the control plane and data
plane may be achieved.
3.8.1. PW Control Plane
An MPLS-TP network provides many of its transport services using
single-segment or multi-segment pseudowires, in compliance with the
PWE3 architecture ([RFC3985] and [I-D.ietf-pwe3-ms-pw-arch] ). The
setup and maintenance of single-segment or multi- segment pseudowires
uses the Label Distribution Protocol (LDP) as per [RFC4447] and
extensions for MS-PWs [I-D.ietf-pwe3-segmented-pw] and
[I-D.ietf-pwe3-dynamic-ms-pw].
3.8.2. LSP Control Plane
MPLS-TP provider edge nodes aggregate multiple pseudowires and carry
them across the MPLS-TP network through MPLS-TP tunnels (MPLS-TP
LSPs). Applicable functions from the Generalized MPLS (GMPLS)
protocol suite supporting packet-switched capable (PSC) technologies
are used as the control plane for MPLS-TP transport paths (LSPs).
The LSP control plane includes:
o RSVP-TE for signalling
o OSPF-TE or ISIS-TE for routing
RSVP-TE signaling in support of GMPLS, as defined in [RFC4872], is
used for the setup, modification, and release of MPLS-TP transport
paths and protection paths. It supports unidirectional, bi-
directional and multicast types of LSPs. The route of a transport
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path is typically calculated in the ingress node of a domain and the
RSVP explicit route object (ERO) is utilized for the setup of the
transport path exactly following the given route. GMPLS based
MPLS-TP LSPs must be able to interoperate with RSVP-TE based MPLS-TE
LSPs, as per [RFC5146]
OSPF-TE routing in support of GMPLS as defined in [RFC4203] is used
for carrying link state information in a MPLS-TP network. ISIS-TE
routing in support of GMPLS as defined in [RFC5307] is used for
carrying link state information in a MPLS-TP network.
3.9. Static Operation of LSPs and PWs
A PW or LSP may be statically configured without the support of a
dynamic control plane. This may be either by direct configuration of
the PEs/LSRs, or via a network management system. The colateral
damage that loops can cause during the time taken to detect the
failure may be severe. When static configuration mechanisms are
used, care must be taken to ensure that loops to not form.
3.10. Survivability
Survivability requirements for MPLS-TP are specified in
[I-D.ietf-mpls-tp-survive-fwk].
A wide variety of resiliency schemes have been developed to meet the
various network and service survivability objectives. For example,
as part of the MPLS/PW paradigms, MPLS provides methods for local
repair using back-up LSP tunnels ([RFC4090]), while pseudowire
redundancy [I-D.ietf-pwe3-redundancy] supports scenarios where the
protection for the PW can not be fully provided by the PSN layer
(i.e. where the backup PW terminates on a different target PE node
than the working PW). Additionally, GMPLS provides a well known set
of control plane driven protection and restoration mechanisms
[RFC4872]. MPLS-TP provides additional protection mechansisms that
are optimised for both linear topologies and ring topologies, and
that operate in the absense of a dynamic control plane. These are
specified in [I-D.ietf-mpls-tp-survive-fwk].
Different protection schemes apply to different deployment topologies
and operational considerations. Such protection schemes may provide
different levels of resiliency. For example, two concurrent traffic
paths (1+1), one active and one standby path with guaranteed
bandwidth on both paths (1:1) or one active path and a standby path
that is shared by one or more other active paths (shared protection).
The applicability of any given scheme to meet specific requirements
is outside the current scope of this document.
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The characteristics of MPLS-TP resiliency mechanisms are listed
below.
o Optimised for linear, ring or meshed topologies.
o Use OAM mechanisms to detect and localize network faults or
service degenerations.
o Include protection mechanisms to coordinate and trigger protection
switching actions in the absense of a dynamic control plane. This
is known as an Automatic Protection Switching (APS) mechanism.
o MPLS-TP recovery schemes are applicable to all levels in the
MPLS-TP domain (i.e. MPLS section, LSP and PW), providing segment
and end-to- end recovery.
o MPLS-TP recovery mechanisms support the coordination of protection
switching at multiple levels to prevent race conditions occuring
between a client and its server layer.
o MPLS-TP recovery mechanisms can be data plane, control plane or
management plane based.
o MPLS-TP supports revertive and non-revertive behavior.
3.11. Network Management
The network management architecture and requirements for MPLS-TP are
specified in [I-D.ietf-mpls-tp-nm-req]. It derives from the generic
specifications described in ITU-T G.7710/Y.1701 [G.7710] for
transport technologies. It also incorporates the OAM requirements
for MPLS Networks [RFC4377] and MPLS-TP Networks
[I-D.ietf-mpls-tp-oam-requirements] and expands on those requirements
to cover the modifications necessary for fault, configuration,
performance, and security in a transport network.
The Equipment Management Function (EMF) of a MPLS-TP Network Element
(NE) (i.e. LSR, LER, PE, S-PE or T-PE) provides the means through
which a management system manages the NE. The Management
Communication Channel (MCC), realized by the G-ACh, provides a
logical operations channel between NEs for transferring Management
information. For the management interface from a management system
to a MPLS-TP NE, there is no restriction on which management protocol
should be used. It is used to provision and manage an end-to-end
connection across a network where some segments are create/managed,
for examples by Netconf or SNMP and other segments by XML or CORBA
interfaces. Maintenance operations are run on a connection (LSP or
PW) in a manner that is independent of the provisioning mechanism.
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An MPLS-TP NE is not required to offer more than one standard
management interface. In MPLS-TP, the EMF must be capable of
statically provisioning LSPs for an LSR or LER, and PWs for a PE, as
per Section 3.9.
Fault Management (FM) functions within the EMF of an MPLS-TP NE
enable the supervision, detection, validation, isolation, correction,
and alarm handling of abnormal conditions in the MPLS-TP network and
its environment. FM must provide for the supervision of transmission
(such as continuity, connectivity, etc.), software processing,
hardware, and environment. Alarm handling includes alarm severity
assignment, alarm suppression/aggregation/correlation, alarm
reporting control, and alarm reporting.
Configuration Management (CM) provides functions to control,
identify, collect data from, and provide data to MPLS-TP NEs. In
addition to general configuration for hardware, software protection
switching, alarm reporting control, and date/time setting, the EMF of
the MPLS-TP NE also supports the configuration of maintenance entity
identifiers (such as MEP ID and MIP ID). The EMF also supports the
configuration of OAM parameters as a part of connectivity management
to meet specific operational requirements. These may specify whether
the operational mode is one-time on-demand or is periodic at a
specified frequency.
The Performance Management (PM) functions within the EMF of an MPLS-
TP NE support the evaluation and reporting of the behaviour of the
NEs and the network. One particular requirement for PM is to provide
coherent and consistent interpretation of the network behaviour in a
hybrid network that uses multiple transport technologies. Packet
loss measurement and delay measurements may be collected and used to
detect performance degradation. This is reported via fault
management to enable corrective actions to be taken (e.g. protection
switching), and via performance monitoring for Service Level
Agreement (SLA) verification and billing. Collection mechanisms for
performance data should be should be capable of operating on-demand
or proactively.
4. Security Considerations
The introduction of MPLS-TP into transport networks means that the
security considerations applicable to both MPLS and PWE3 apply to
those transport networks. Furthermore, when general MPLS networks
that utilise functionality outside of the strict MPLS-TP profile are
used to support packet transport services, the security
considerations of that additional functionality also apply.
The security considerations of [RFC3985] and
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[I-D.ietf-pwe3-ms-pw-arch] apply.
Each MPLS-TP solution must specify the addtional security
considerations that apply.
5. IANA Considerations
IANA considerations resulting from specific elements of MPLS-TP
functionality will be detailed in the documents specifying that
functionality.
This document introduces no additional IANA considerations in itself.
6. Acknowledgements
The editors wish to thank the following for their contribution to
this document:
o Dieter Beller
o Italo Busi
o Hing-Kam Lam
o Marc Lasserre
o Vincenzo Sestito
o Martin Vigoureux
o Malcolm Betts
7. References
7.1. Normative References
[G.7710] "ITU-T Recommendation G.7710/
Y.1701 (07/07), "Common
equipment management function
requirements"", 2005.
[I-D.ietf-mpls-cosfield-def] Andersson, L. and R. Asati,
"Multi-Protocol Label Switching
(MPLS) label stack entry: "EXP"
field renamed to "Traffic
Class" field",
draft-ietf-mpls-cosfield-def-08
(work in progress),
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December 2008.
[I-D.ietf-pwe3-ms-pw-arch] Bocci, M. and S. Bryant, "An
Architecture for Multi-Segment
Pseudowire Emulation Edge-to-
Edge",
draft-ietf-pwe3-ms-pw-arch-06
(work in progress),
February 2009.
[I-D.ietf-pwe3-redundancy] Muley, P. and M. Bocci,
"Pseudowire (PW) Redundancy",
draft-ietf-pwe3-redundancy-01
(work in progress),
September 2008.
[RFC2119] Bradner, S., "Key words for use
in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119,
March 1997.
[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.
[RFC3270] Le Faucheur, F., Wu, L., Davie,
B., Davari, S., Vaananen, P.,
Krishnan, R., Cheval, P., and J.
Heinanen, "Multi-Protocol Label
Switching (MPLS) Support of
Differentiated Services",
RFC 3270, May 2002.
[RFC3471] Berger, L., "Generalized Multi-
Protocol Label Switching (GMPLS)
Signaling Functional
Description", RFC 3471,
January 2003.
[RFC3985] Bryant, S. and P. Pate, "Pseudo
Wire Emulation Edge-to-Edge
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(PWE3) Architecture", RFC 3985,
March 2005.
[RFC4090] Pan, P., Swallow, G., and A.
Atlas, "Fast Reroute Extensions
to RSVP-TE for LSP Tunnels",
RFC 4090, May 2005.
[RFC4201] Kompella, K., Rekhter, Y., and
L. Berger, "Link Bundling in
MPLS Traffic Engineering (TE)",
RFC 4201, October 2005.
[RFC4203] Kompella, K. and Y. Rekhter,
"OSPF Extensions in Support of
Generalized Multi-Protocol Label
Switching (GMPLS)", RFC 4203,
October 2005.
[RFC4385] Bryant, S., Swallow, G.,
Martini, L., and D. McPherson,
"Pseudowire Emulation Edge-to-
Edge (PWE3) Control Word for Use
over an MPLS PSN", RFC 4385,
February 2006.
[RFC4447] Martini, L., Rosen, E., El-
Aawar, N., Smith, T., and G.
Heron, "Pseudowire Setup and
Maintenance Using the Label
Distribution Protocol (LDP)",
RFC 4447, April 2006.
[RFC4872] Lang, J., Rekhter, Y., and D.
Papadimitriou, "RSVP-TE
Extensions in Support of End-to-
End Generalized Multi-Protocol
Label Switching (GMPLS)
Recovery", RFC 4872, May 2007.
[RFC5085] Nadeau, T. and C. Pignataro,
"Pseudowire Virtual Circuit
Connectivity Verification
(VCCV): A Control Channel for
Pseudowires", RFC 5085,
December 2007.
[RFC5307] Kompella, K. and Y. Rekhter,
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Internet-Draft MPLS TP Framework June 2009
"IS-IS Extensions in Support of
Generalized Multi-Protocol Label
Switching (GMPLS)", RFC 5307,
October 2008.
[RFC5462] Andersson, L. and R. Asati,
"Multiprotocol Label Switching
(MPLS) Label Stack Entry: "EXP"
Field Renamed to "Traffic Class"
Field", RFC 5462, February 2009.
[RFC5586] Bocci, M., Vigoureux, M., and S.
Bryant, "MPLS Generic Associated
Channel", RFC 5586, June 2009.
7.2. Informative References
[I-D.bryant-filsfils-fat-pw] Bryant, S., Filsfils, C., Drafz,
U., Kompella, V., Regan, J., and
S. Amante, "Flow Aware Transport
of MPLS Pseudowires",
draft-bryant-filsfils-fat-pw-03
(work in progress), March 2009.
[I-D.ietf-bfd-mpls] Aggarwal, R., Kompella, K.,
Nadeau, T., and G. Swallow, "BFD
For MPLS LSPs",
draft-ietf-bfd-mpls-07 (work in
progress), June 2008.
[I-D.ietf-mpls-tp-nm-req] Mansfield, S. and K. Lam, "MPLS
TP Network Management
Requirements",
draft-ietf-mpls-tp-nm-req-02
(work in progress), June 2009.
[I-D.ietf-mpls-tp-oam-framework] Busi, I. and B. Niven-Jenkins,
"MPLS-TP OAM Framework and
Overview", draft-ietf-mpls-tp-
oam-framework-00 (work in
progress), March 2009.
[I-D.ietf-mpls-tp-oam-requirements] Vigoureux, M., Ward, D., and M.
Betts, "Requirements for OAM in
MPLS Transport Networks", draft-
ietf-mpls-tp-oam-requirements-02
(work in progress), June 2009.
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[I-D.ietf-mpls-tp-requirements] Niven-Jenkins, B., Brungard, D.,
Betts, M., Sprecher, N., and S.
Ueno, "MPLS-TP Requirements", dr
aft-ietf-mpls-tp-requirements-09
(work in progress), June 2009.
[I-D.ietf-mpls-tp-survive-fwk] Sprecher, N., Farrel, A., and H.
Shah, "Multiprotocol Label
Switching Transport Profile
Survivability Framework", draft-
ietf-mpls-tp-survive-fwk-00
(work in progress), April 2009.
[I-D.ietf-pwe3-dynamic-ms-pw] Martini, L., Bocci, M., Bitar,
N., Shah, H., Aissaoui, M., and
F. Balus, "Dynamic Placement of
Multi Segment Pseudo Wires",
draft-ietf-pwe3-dynamic-ms-pw-09
(work in progress), March 2009.
[I-D.ietf-pwe3-segmented-pw] Martini, L., Nadeau, T., Metz,
C., Duckett, M., Bocci, M.,
Balus, F., and M. Aissaoui,
"Segmented Pseudowire",
draft-ietf-pwe3-segmented-pw-12
(work in progress), June 2009.
[RFC4377] Nadeau, T., Morrow, M., Swallow,
G., Allan, D., and S.
Matsushima, "Operations and
Management (OAM) Requirements
for Multi-Protocol Label
Switched (MPLS) Networks",
RFC 4377, February 2006.
[RFC4379] Kompella, K. and G. Swallow,
"Detecting Multi-Protocol Label
Switched (MPLS) Data Plane
Failures", RFC 4379,
February 2006.
[RFC5146] Kumaki, K., "Interworking
Requirements to Support
Operation of MPLS-TE over GMPLS
Networks", RFC 5146, March 2008.
Bocci, et al. Expires December 31, 2009 [Page 30]
Internet-Draft MPLS TP Framework June 2009
Authors' Addresses
Matthew Bocci (editor)
Alcatel-Lucent
Voyager Place, Shoppenhangers Road
Maidenhead, Berks SL6 2PJ
United Kingdom
Phone: +44-207-254-5874
EMail: matthew.bocci@alcatel-lucent.com
Stewart Bryant (editor)
Cisco Systems
250 Longwater Ave
Reading RG2 6GB
United Kingdom
Phone: +44-208-824-8828
EMail: stbryant@cisco.com
Lieven Levrau
Alcatel-Lucent
7-9, Avenue Morane Sulnier
Velizy 78141
France
Phone: +33-6-33-86-1916
EMail: lieven.levrau@alcatel-lucent.com
Bocci, et al. Expires December 31, 2009 [Page 31]
