Internet Engineering Task Force

Pseudowire Emulation Edge to Edge (pwe3)

In addition to this official charter maintained by the IETF Secretariat, there is additional information about this working group on the Web at:
MPLS Architectural Considerations for a Transport

Last Modified: 2009-04-13

Additional information is available at tools.ietf.org/wg/pwe3

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Description of Working Group:

Network transport service providers and their users are
seeking to rationalize their networks by migrating their
existing services and platforms onto IP or MPLS enabled
IP packet switched networks (PSN). This migration requires
communications services that can emulate the essential
properties of traditional communications links over a PSN.
Some service providers wish to use MPLS technology to
replace existing transport network infrastructure, relying
upon pseudowire technology is an integral component of
these network convergence architectures.

Pseudowire Emulation Edge to Edge (PWE3) will specify the
encapsulation, transport, control, management, interworking
and security of services emulated over IETF-specified PSNs.

A pseudowire emulates a point-to-point or point-to-multipoint
link, and provides a single service which is perceived by
its user as an unshared link or circuit of the chosen
service. It is not intended that an emulated service will
be indistinguishable from the service that is being emulated.
The emulation need only be sufficient for the satisfactory
operation of the service. Emulation necessarily involves a
degree of cost-performance trade-off. In some cases it may
be necessary to design more than one emulation mechanism in
order to resolve these design conflicts. All emulated service
definitions must include an applicability statement describing
the faithfulness of the emulation.

Switching, multiplexing, modification or other operation on
the traditional service, unless required as part of the
emulation, is out of the scope of the PWE3 WG.

PWE3 will make use of existing IETF-specified mechanisms
unless there are technical reasons why the existing mechanisms
are insufficient or unnecessary.

PWE3 operates "edge to edge" and will not exert control on
the underlying PSN, other than to use any existing QoS or
path control mechanism to provide the required connectivity
between the endpoints of the PW.

PWE3 will co-ordinate this with the AVT and TICTOC WGs.
Where AVT or TICTOC require extensions to PWs to support
time or frequency transfer this work will be undertaken by
the PWE3 WG in co-ordination with the these WGs.

A PW operating over a shared PSN does not necessarily have
the same intrinsic security as a dedicated, purpose built,
network. In some cases this is satisfactory, while in other
cases it will be necessary to enhance the security of the PW
to emulate the intrinsic security of the emulated service.
PW specifications MUST include a description of how they
are to be operated over a shared PSN with adequate security.
PWE3 will work with the MPLS, L2VPN and other relevant WGs
for definitions of common solutions for the secure operation
of pseudowires.

Whilst a service provider may traffic engineer their network
in such a way that PW traffic will not cause significant
congestion, a PW deployed by an end-user may cause
congestion of the underlying PSN. Suitable congestion
avoidance mechanisms are therefore needed to protect the
Internet from the unconstrained deployment of PWs. Congestion
avoidance may be more difficult with P2MP pseudowires than
P2P pseudowires. The WG will consider both cases.

PWE3 will work closely with the L2VPN WG to ensure a clear
demarcation is defined for where PWE3 stops and L2VPN starts,
in particular in defining point-multipoint (P2MP) PWs.

PWE3 will work with MPLS and L2VPN to enhance the OAM suite
for transport applications. PWE3 will coordinate very closely
with any WG that is responsible for protocols which PWE3
intends to extend (e.g., the MPLS WG for LDP), as well as
foster interaction with WGs that intend to extend PWE3
protocols.

The IETF PWE3 WG is the design authority for pseudo-wire
over IP/MPLS PSN technology. An entity or individual that
wishes to propose extensions or changes to this technology
must bring the corresponding proposals to the PWE3 WG that
would treat them via a process similar to one described in
RFC 4929 for the MPLS/GMPLS change process.

WG Objectives:

Specify the following PW types:

Most of the initial specific PW types have been specified
(e.g., Frame Realy, Ethernet, ATM). Investigation into
and specification of a "generic PW" type and/or MPLS PW
should be undertaken.

PWE3 will specify a PW type for the special case where the
access service payloads at both ends are known to consist
entirely of IP packets. PWE3 will not specify mechanisms
by which a PW connects two different access services
unless the Network Layer protocol is IP or MPLS.

Specify the control and management functions of chartered PW
types, to include PW setup, configuration, maintenance and
tear-down. The PWE3 WG will do this in its entirety for
MPLS PSNs, and the L2TPEXT WG will develop the L2TP specifics
for L2TPv3-based PWs.

Specify Operations and Management (OAM) mechanisms for all
PW types, suitable for operation over both IP/L2TPv3 and
MPLS PSNs, and capable of providing the necessary
interworking with the OAM mechanisms of the emulated
service.

Define requirements for and mechanisms to provide
interconnection of PWs (to include inter-domain PWs).

Define requirements for and mechanisms to provide
protection and restoration of PWs.

Publish document outlining PW-specific congestion avoidance
and response guidelines.

Publish document outlining PW-specific security
considerations.

Specify requirements and mechanisms for P2MP functionality
for PWs. This work will be coordinated with the L2VPN and
MPLS working groups.

Publish requirements and specification for PW to take
advantage of multiple PSN paths that exist between PEs.

Publish requirements and specification for enhanced OAM.

Include extensions to the PWE3 protocols and RFCs
necessary to create an MPLS Transport Profile (MPLS-TP).
The work on the MPLS TP needs to be coordinated between
three primary working groups (MPLS, PWE3, L2VPN and CCAMP) that
are chartered to do MPLS TP work.

Goals and Milestones:

Done		PWE3 WG started, organize editing teams.
Done		Hold interim meeting, including discussion of priority of service-specific documents and consider pruning some deliverables
Done		Accept drafts of service-specific documents as WG items
Done		PW Requirements Document Last Call
Done		TDM Circuit Documents Last Call
Done		ATM Documents Last Call
Done		Ethernet Documents Last Call
Done		Fragmentation LC
Done		TDM Requirements LC
Done		SONET Documents Last Call
Done		TDM Documents Last Call
Done		Frame Relay Documents Last Call
Done		FCS retention Last Call
Done		Multi-Segment PW Requirements LC
Done		VCCV LC
Done		PWE3 Services MIBs LC
Done		PPP/HDLC PW LC
Done		Wildcard FEC LC
Done		TDM Signaling LC
Jul 2008		Multi-Segment Architecture LC
Done		Basic Pseudowire MIBs LC
Sep 2008		Fiber Channel Encap LC
Sep 2008		PW OAM Mapping LC
Sep 2008		Congestion Framework LC
Oct 2008		Multi-Segment PW LC
Dec 2008		PW Protection and Restoration Requirements LC
Dec 2008		PW Congestion Response LC
Dec 2008		Generic PW Requirements
Jan 2009		Dynamic MS PW LC
Mar 2009		PW Protection and Restoration Architecture
Mar 2009		Multipath PW LC
Mar 2009		Generic Associated Channel Header LC
Apr 2009		MPLS PW LC
Jul 2009		PW Protection and Restoration LC
Jul 2009		Multisegment PW MIB
Jul 2009		Congestion Solution LC
Jul 2009		Security Considerations LC
Jul 2009		P2MP Requirements LC
Dec 2009		Enhanced PW OAM
Dec 2009		VCCV Extensions for MPLS-TP
Dec 2009		Tandem Connection Monitoring for PWs

Internet-Drafts:

SONET/SDH Circuit Emulation Service Over Packet (CEP) Management Information Base (MIB) Using SMIv2 (131124 bytes)
Segmented Pseudowire (95950 bytes)
Dynamic Placement of Multi Segment Pseudo Wires (38696 bytes)
Application of Ethernet Pseudowires to MPLS Transport Networks (24054 bytes)
Bidirectional Forwarding Detection (BFD) for the Pseudowire Virtual Circuit Connectivity Verification (VCCV) (32336 bytes)
Preferential Forwarding Status bit definition (67758 bytes)
Pseudowire (PW) Redundancy (31351 bytes)
Requirements for Point-to-Multipoint Pseudowire (47515 bytes)
LDP extensions for AII reachability (24125 bytes)
MPLS and Ethernet OAM Interworking (37543 bytes)
Inter-Chassis Communication Protocol for L2VPN PE Redundancy (127641 bytes)
Flow Aware Transport of Pseudowires over an MPLS PSN (40186 bytes)

Request For Comments:

Requirements for Pseudo-Wire Emulation Edge-to-Edge (PWE3) (RFC 3916) (43856 bytes)
PWE3 Architecture (RFC 3985) (95062 bytes) updated by RFC 5462
Requirements for Edge-to-Edge Emulation of Time Division Multiplexed (TDM) Circuits over Packet Switching Networks (RFC 4197) (47937 bytes)
Pseudowire Emulation Edge-to-Edge (PWE3) Control Word for Use over an MPLS PSN (RFC 4385) (22440 bytes) updated by RFC 5586
IANA Allocations for Pseudowire Edge to Edge Emulation (PWE3) (RFC 4446) (19782 bytes)
Pseudowire Setup and Maintenance using the Label Distribution Protocol (LDP) (RFC 4447) (76204 bytes)
Encapsulation Methods for Transport of Ethernet Over MPLS Networks (RFC 4448) (49012 bytes) updated by RFC 5462
Structure-Agnostic Time Division Multiplexing (TDM) over Packet (SAToP) (RFC 4553) (58141 bytes)
Pseudowire Emulation Edge-to-Edge (PWE3) Fragmentation and Reassembly (RFC 4623) (36369 bytes)
Encapsulation Methods for Transport of Frame Relay Over MPLS Networks (RFC 4619) (38193 bytes)
Encapsulation Methods for Transport of PPP/High-Level Data Link Control (HDLC) over MPLS Networks (RFC 4618) (33141 bytes)
Pseudowire Emulation Edge-to-Edge (PWE3) Frame Check Sequence Retention (RFC 4720) (18248 bytes)
Encapsulation Methods for Transport of Asynchronous Transfer Mode (ATM) over MPLS Networks (RFC 4717) (86173 bytes)
Pseudowire Emulation Edge-to-Edge (PWE3) Asynchronous Transfer Mode (ATM) Transparent Cell Transport Service (RFC 4816) (10269 bytes)
Synchronous Optical Network/Synchronous Digital Hierarchy SONET/SDH) Circuit Emulation over Packet (CEP)) (RFC 4842) (96719 bytes) obsoletes RFC 5143
Wildcard Pseudowire Type (RFC 4863) (11321 bytes)
Attachment Individual Identifier (AII) Types for Aggregation (RFC 5003) (14559 bytes)
Time Division Multiplexing over IP (TDMoIP) (RFC 5087) (113071 bytes)
Structure-Aware Time Division Multiplexed (TDM) Circuit Emulation Service over Packet Switched Network (CESoPSN) (RFC 5086) (83233 bytes)
Pseudowire Virtual Circuit Connectivity Verification (VCCV) A Control Channel for Pseudowires (RFC 5085) (67853 bytes) updated by RFC 5586
Control Protocol Extensions for the Setup of Time-Division Multiplexing (TDM) Pseudowires in MPLS Networks (RFC 5287) (33070 bytes)
Requirements for Multi-Segment Pseudowire Emulation Edge-to-Edge (PWE3) (RFC 5254) (64584 bytes)
Definitions of Textual Conventions for Pseudowires (PW) Management (RFC 5542) (19948 bytes)
Pseudowire (PW) over MPLS PSN Management Information Base (MIB) (RFC 5602) (62005 bytes)
Ethernet Pseudowire (PW) Management Information Base (MIB) (RFC 5603) (44125 bytes)
Pseudowire (PW) Management Information Base (MIB) (RFC 5601) (129328 bytes)
Managed Objects for Time Division Multiplexing (TDM) over Packet Switched Networks (RFC 5604) (80002 bytes)
Managed Objects for ATM over Packet Switched Networks (PSNs) (RFC 5605) (69401 bytes)
An Architecture for Multi-Segment Pseudowire Emulation Edge-to-Edge (RFC 5659) (55614 bytes)