Network Working Group F. Jounay
Internet Draft P. Niger
Category: Informational Track France Telecom
Expires: August 2007
Y. Kamite
L. Martini NTT Communications
Cisco
S. Delord
G. Heron Uecomm
Tellabs
L. Wang
Telenor
February 26, 2007
Use Cases and signaling requirements for Point-to-Multipoint PW
draft-jounay-pwe3-p2mp-pw-requirements-00.txt
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Abstract
This document provides some use cases advocating for the definition
of a unidirectional Point-to-Multipoint Pseudowire (P2MP PW). Based
on these use cases it also presents a set of requirements for the set
up and maintenance of P2MP PW, proposed as guidelines for possible
solutions.
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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].
Table of Contents
1. Introduction................................................3
1.1. Problem Statement...........................................3
1.2. Scope of the document.......................................3
2. Definition..................................................4
2.1. Acronyms....................................................4
2.2. Terminology.................................................4
3. Use Cases for P2MP PW.......................................5
3.1. TDM-based Use Case..........................................5
3.2. ATM-based Use Case..........................................6
3.3. Ethernet-based Use Case.....................................6
3.3.1. P2MP PW for VPLS............................................6
3.3.2. P2MP PW for Ethernet-based VPWS.............................6
4. P2MP SS-PW Requirements.....................................7
4.1. P2MP SS-PW Reference Model..................................7
4.2. P2MP SS-PW Underlying Layer.................................8
4.3. P2MP SS-PW Signaling Requirements...........................8
4.3.1. P2MP SS-PW Setup Mechanisms.................................8
4.3.2. Leaf Grafting/Pruning.......................................8
4.4. Failure Reporting and Processing............................9
4.5. Advertisement of P2MP Capability............................9
4.6. Scalability.................................................9
4.7. Order of Magnitude.........................................10
5. P2MP MS-PW Requirements....................................10
5.1. P2MP MS-PW Pseudowire Reference Model......................10
5.2. P2MP SS-PW Underlying Layer................................11
5.3. P2MP MS-PW Signaling Requirements..........................12
5.3.1. PW Addresses Routing.......................................12
5.3.2. P2MP MS-PW Setup Mechanisms................................12
5.3.3. Leaf Grafting/Pruning......................................12
5.3.4. Explicit Routing...........................................13
5.4. Failure Reporting..........................................13
5.5. Protection and Restoration.................................13
5.6. Advertisement of P2MP Capability...........................14
5.7. Scalability................................................14
5.8. Order of Magnitude.........................................14
6. Manageability considerations...............................15
7. Backward Compatibility.....................................15
8. Security Considerations....................................15
9. IANA Considerations........................................15
10. Acknowledgments............................................15
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11. References.................................................15
11.1. Normative References........................................15
11.2. Informative References......................................15
Authors' Addresses.................................................16
Intellectual Property and Copyright Statements.....................17
1. Introduction
1.1. Problem Statement
As defined in the PWE3 WG charter, a Pseudowire (PW) emulates a
point-to-point bidirectional link over an IP/MPLS network, and
provides a single service which is perceived by its user as an
unshared link or circuit of the chosen service. A Pseudowire is used
to transport non IP traffics (e.g. Ethernet, TDM, ATM, and FR) in a
MPLS-based PSN (Packet Switched Network). PWE3 operates "edge to
edge" to provide the required connectivity between the two endpoints
of the PW.
For some use cases described hereafter, some P2MP services require
the use of Pseudowire for their encapsulation capabilities. This
could be achieved using a set of point to point PWs, with traffic
replication on the Ingress PE, but faces obvious bandwidth limitation
issues, as traffic is carried multiple time on shared links. To avoid
such bandwidth wastings, an alternative solution consists of using a
unique Point to Multipoint PW (P2MP PW) that is a unidirectional PW
with one Ingress PE and a set of one or more Egress PEs, and without
traffic replication on Ingress PE.
This document aims at describing possible use cases for P2MP PW and
defining the associated requirements related to the P2MP PW setup and
maintenance.
It is intended that solutions that specify procedures and protocols
or extensions to existing protocols for the signaling of P2MP
Pseudowire satisfy these requirements.
1.2. Scope of the document
The first part of the document aims at listing a set of use cases
which would take benefits of the use of a unidirectional P2MP
Pseudowire rather than multiple point to point Pseudowires.
The second part describes the specific signaling requirements for the
set up and maintenance of a P2MP PW. The requirements are divided
into two parts, i.e. those applicable in a Single-Segment topology
and those applicable in a Multi-Segment topology. For other aspects
of P2MP PW implementation like packet processing, maintenance, etc,
the document refers to [RFC3916].
Some P2MP PW requirements are derived from the signaling requirements
for P2MP Traffic-Engineered MPLS Label Switched Paths [RFC4461].
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2. Definition
2.1. Acronyms
P2P: Point-to-Point
P2MP: Point-to-Multipoint
PW: Pseudowire
SS-PW: Single-Segment Pseudowire
MS-PW: Multi-Segment Pseudowire
2.2. Terminology
This document uses terminology described in [MS-PW REQ], [MS-PW
ARCH], [SEG PW].
It also introduces additional terms needed in the context of
unidirectional P2MP PW.
P2MP PW, (also referred as PW Tree)
Point-to-Multipoint Pseudowire. A PW attached to a source used to
distribute L1/L2 format traffic to a set of one or more receivers (or
leaves). The P2MP PW is unidirectional.
P2MP SS-PW
Point-to-Multipoint Single-Segment Pseudowire. A single segment P2MP
PW set up between the PE attached to the source and the PEs attached
to the receivers. The P2MP SS-PW relies on a P2MP LSP as PSN tunnel.
P2MP MS-PW
Point-to-Multipoint Multi-Segment Pseudowire. A multi-segment P2MP PW
represents an End-to-End PW segmented by means of S-PEs which are in
charge of switching the PW label. Each segment can rely on either
P2P LSP or a P2MP LSP as PSN tunnel.
Ingress PE
P2MP PW Ingress Provider Edge. Router attached to a Customer
Equipment (traffic source) via an Attachment Circuit (AC). In a MS-PW
architecture the term used is Ingress T-PE.
Egress PE
P2MP PW Egress Provider Edge. Router attached to a set of on or more
Customer Equipments (traffic receivers or leaves) via a set of one or
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more Attachment Circuits (AC). In a MS-PW architecture the term used
is Egress T-PE.
Branch S-PE
The branch S-PE is only defined and required in the context of MS-PW.
The branch S-PE has one upstream PW segment and one or several
downstream PW segments.
3. Use Cases for P2MP PW
3.1. TDM-based Use Case
In a PSN environment, PWs allow supporting 2G/3G mobile backhauling
(e.g. TDM traffic for GSM's Abis interface, ATM traffic for Release
99 UMTS's Iub interface). At the time being, the Mobile backhauling
architecture is always built as a star topology between the 2G/3G
controller (e.g. BSC or RNC) and the 2G/3G Base Stations (BTS or
NodeB). Therefore P2P PWs are used between each Base Station and
their corresponding controller and nothing more is required.
As far as synchronization in a PSN environment is concerned,
different mechanisms can be considered to provide frequency and phase
clock required in the 2G/3G Mobile environment to guarantee mobile
handover and strict QoS. One of them consists in using Adaptive Clock
Distribution and Recovery. With this method a Master element
distributes a reference clock at protocol level by regularly sending
TDM PW packets (SAToP, CESoPSN or TDMoIP) to Slave elements. This
process is based on the fact that the volume of transmitted data
arrival is considered as an indication of the source frequency that
could be used by the Slave element to recover the source clock
frequency. Consequently, with the current methods, the PE connected
to the Master must setup and maintain as many P2P PWs as we have
Slave elements, and it has to replicate the traffic. A better
solution to deliver the clock frequency would be to use a P2MP PW.
This may scale much more than P2P PWs with regards to the forwarding
plane at the Ingress PE since the traffic coming from the Master is
no more replicated to the P2P PWs but only to the outgoing interface
corresponding to the P2MP PW. It may ease the provisioning process
since only one PW source endpoint must be configured at the Ingress
PE. This alleviated provisioning process would be particularly
appreciated for the introduction of new Base Stations. The main gain
would be to avoid replication on the Ingress PE and hence save
bandwidth consumed by the synchronization traffic which typically
requires the highest level of QoS. This kind of traffic will be
competing with equivalent QOS traffic like VoIP, that is why it is
significant to save the slightest bandwidth.
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3.2. ATM-based Use Case
A use case of ATM-based P2MP PW could be to offer the capability for
service providers to support IP multicast wholesale services over ATM
in case the wholesale customer relies on ATM infrastructure. The PW
P2MP alleviates the constraint in terms of replication for ATM to
support IP multicast services. Today most video distribution networks
require point-to-multipoint as well as point-to-point transport for
live broadcasting and non-live contents distribution. As for point-
to-multipoint traffic, there are some traditional approaches to
convey it, for example, by ATM based duplication (point-to-multipoint
PVP/PVCs). Terminal CE devices in such environment support legacy
protocol interfaces only as such. However, the trend to migrate such
an old network onto MPLS/IP-based backbone is still growing now.
Hence it is expected that a standard Pseudo Wire setup/encapsulation
method will support point-to-multipoint transport of various kinds of
conventional protocols.
3.3. Ethernet-based Use Case
3.3.1. P2MP PW for VPLS
The requirements for Multicast Support in VPLS is described in [VPLS
MCAST REQ]. P2MP Pseudo wire might be able to be applied as an
efficient PW forwarding mechanism for multicast VPLS.
3.3.2. P2MP PW for Ethernet-based VPWS
VPLS supports only Ethernet service. If you need other protocols be
natively transported in point-to-multipoint way, P2MP PW would be a
candidate alternative.
VPLS natively requires MAC-based learning and forwarding, however
video distribution applications generally use a single tree like
network topology, and do not require the added expense of MAC
learning.
VPLS natively connects multiple all CEs as default, but for some
applications that provide just point-to-multipoint type transport,
traffic from receiver to sender is not needed, and traffic between
different receivers directly are not needed, either. In this case,
P2MP PWS provides much simpler operation to it.
Note that P2MP PW has a limitation in the point of its uni-
directional service model. If the application layer needs bi-
directional communication at CE, some additional techniques may be
necessary to support.
As mentioned above the use case related to Ethernet-based P2MP PW is
particularly focused on VPWS which does not require features hold by
the VSI (MAC learning, MAC forwarding) or auto-discovery procedures
in VPLS.
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The P2MP VPWS is typically a service required when a service provider
wants to deliver in a cross-connect mode traffic from one endpoint to
several endpoints.
4. P2MP SS-PW Requirements
4.1. P2MP SS-PW Reference Model
Note: the P2MP SS-PW reference model presented in this document
refers to the one defined in [PW MCAST]. The format differs only to
get a common model for the P2MP SS-PW and P2MP MS-PW.
A unidirectional P2MP SS-PW provides a Point-to-Multipoint
connectivity from an Ingress PE connected to a traffic source to at
least two Egress PEs connected to traffic receivers. The PW endpoints
connect the PW to its attachment circuits (AC). As for a P2P PW, an
AC can be a Frame Relay DLCI, an ATM VPI/VC, an Ethernet port, a
VLAN, a HDLC link, a PPP connection on a physical interface.
Figure 1 describes the P2MP SS-PW reference model which is derived
from [RFC3985] to support P2MP emulated services.
|<-----------P2MP SS-PW------------>|
Native | | Native
Service | |<----P2MP PSN tunnel --->| | Service
(AC) V V V V (AC)
| +----+ +-----+ +----+ |
| |PE1 | | P |=========|PE2 | | +----+
| | | | ......PW1........|-----------|CE2 |
| | | | . |=========| | | +----+
| | | | . | +----+ |
| | |=========| . | |
| | | | . | +----+ |
+----+ | | | | . |=========|PE3 | | +----+
|CE1 |---------|........PW1.........|...PW1........|-----------|CE3 |
+----+ | | | | . |=========| | | +----+
| | | | . | +----+ |
| | |=========| . | |
| | | | . | +----+ |
| | | | . |=========|PE4 | | +----+
| | | | ......PW1........|-----------|CE4 |
| | | | |=========| | | +----+
| +----+ +-----+ +----+ |
Figure 1 P2MP SS-PW Reference Model
This architecture applies to the case where a P2MP PSN tunnel extends
between edge nodes of a single PSN domain to transport a
unidirectional P2MP PW with endpoints at these edge nodes.
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In this model a single copy of each PW packet is sent over the P2MP
PSN tunnel and is received by all Egress PEs due to the P2MP nature
of the PSN tunnel.
4.2. P2MP SS-PW Underlying Layer
The P2MP SS-PW implies an underlying P2MP PSN tunnel. Figure 2 gives
an example of P2MP SS-PW topology relying on a P2MP LSP. The PW tree
is composed of one Ingress PE (i1) and several Egress PEs (e1, e2,
e3, e4).
Depending on the Traffic-Engineering requirements, the P2MP PSN will
be signaled with P2MP RSVP-TE [P2MP RSVP-TE] or MLDP [MLDP].
i1
/
/ \
/ \
/ \
/\ \
/ \ \
/ \ \
/ \ / \
e1 e2 e3 e4
Figure 2 Example of P2MP Underlying Layer for P2MP SS-PW
As described in 4.3.1 the PW label MUST be upstream assigned by the
Ingress PE. When the Egress PE receives the upstream label, it MUST
learn in meantime the associated context, i.e. the P2MP LSP on which
the P2MP PW is setup. When the traffic is received at the Egress PE,
the Egress PE MUST check the PW label but also the LSP label to
determine the L2VPN to which the packet belongs to. To achieve the
PHP (Penultimate Hop Popping) must be deactivated on the P2MP LSP.
4.3. P2MP SS-PW Signaling Requirements
4.3.1. P2MP SS-PW Setup Mechanisms
The PW setup could be either leaf initiated or source initiated. Some
P2MP application may request a dynamic tree setup with efficient
provisioning procedure. In that case a source-initiated mode SHOULD
be selected.
Due to the underlying P2MP PSN tunnel, the PW label MUST be upstream
assigned by the Ingress PE.
4.3.2. Leaf Grafting/Pruning
Once the PW tree is setup, the solution MUST allow the addition or
removal of a leaf, or a subset of leaves to/from the existing tree,
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without any impact on the PW tree (data and control planes) for the
remaining leaves.
Such PW Tree leaf grafting/pruning could be source or leaf-initiated.
4.4. Failure Reporting and Processing
Since the underlying layer has an End-to-End P2MP topology between
the Ingress PE and the Egress PEs, the failure reporting and
processing procedures are implemented only on the edge nodes.
Failure events may cause one or more Egress PEs and associated leaves
to become detached from the PW tree. These events MUST be reported to
the Ingress PE, using appropriate in-band or out-band OAM messages.
The solution SHOULD allow the Ingress PE to be informed of Egress PEs
and associated leaves failure for management purposes.
Based on these failure notifications the solution must allow the
Ingress PE to update the remaining leaves of the PW tree.
- A solution MUST support in-band OAM mechanism to detect failures:
unidirectional point-to-multipoint traffic failure.
- In case of failure, it SHOULD correctly report which leaf PEs are
affected. It SHOULD be realized by enhancing existing unicast PW
methods, such as VCCV for seamless and familiar operation.
- A solution MAY support OAM message mapping at PE if failure happens
i.e., mapping AC service OAM between P2MP PW OAM. (This needs more
discussion)
In addition it is assumed that if recovery procedures are required
the P2MP LSP will support the classic recovery techniques mainly
based on RSVP-TE. A mechanism should be implemented to avoid race
conditions between recovery at the PSN level and recovery at the PW
level.
4.5. Advertisement of P2MP Capability
The solution should be completely backward compatible with
the current PW standards. The solution should take into account the
capability advertisement and negotiation procedures for the PEs
implementing P2MP SS-PW endpoints.
Implementation of OAM mechanisms also implies the advertisement of PE
capabilities to support specific OAM features. The solution SHOULD
allow advertising P2MP PW OAM capabilities.
4.6. Scalability
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The solution should scale at least as well as linearly with an
increase in the number of Egress PEs.
The solution SHOULD provide a simple provisioning procedure to build
a P2MP SS-PW. This is related to manageability not scalability.
4.7. Order of Magnitude
This section will be filled in a future version.
Number of Egress PE, TAII per Egress PE, dynamicity (Leaf
Grafting/Pruning) required, etc.
5. P2MP MS-PW Requirements
5.1. P2MP MS-PW Pseudowire Reference Model
Figure 3 describes the P2MP MS-PW reference model which is derived
from [MS-PW ARCH] to support P2MP emulated services.
|<-----------P2MP MS-PW------------>|
Native | | Native
Service | |<-PSN1-->| |<--PSN2->| | Service
(AC) V V V V V V (AC)
| +----+ +-----+ +----+ |
| |T-PE| |S-PE |=========|T-PE| | +----+
| | 1 | | ......PW2......2.|-----------|CE2 |
| | | | . |=========| | | +----+
| | | | . | +----+ |
| | |=========| . | |
| | | | . | +----+ |
+----+ | | | | . |=========|T-PE| | +----+
|CE1 |---------|........PW1.........|...PW3......3.|-----------|CE3 |
+----+ | | | | . |=========| | | +----+
| | | | . | +----+ |
| | |=========| . | |
| | | | . | +----+ |
| | | | . |=========|T-PE| | +----+
| | | | . | .......4.|-----------|CE4 |
| | | | . | . | | | +----+
| | | | ....PW4.. +----+ |
| | | | | . +----+ |
| | | | | . |T-PE| | +----+
| | | | | .......5.|-----------|CE5 |
| | | | |=========| | | +----+
| +----+ +-----+ +----+ |
Figure 3 P2MP MS-PW Reference Model
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Figure 3 extends the P2MP SS-PW architecture of Figure 1 to a multi-
segment configuration. In a P2P MS-PW configuration as described in
[MS-PW REQ] the S-PE is responsible to switch a MS-PW from one input
segment to only one output segment, based on the PW identifier. Here
in a P2MP MS-PW configuration the S-PE is responsible to switch a MS-
PW from one input segment to one or several output segments.
Referring to Figure 3 T-PE1 is the Ingress T-PE and T-PE2, T-PE3, T-
PE4 and T-PE5 are the Egress T-PEs. In the reference model, the
Egress T-PEs are assumed to be located in the same PSN (PSN2), but it
could be envisioned that each output PW is located in a different PSN
(PSN2, PSN3, PSN4). The S-PE plays the role of branch S-PE since it
is in charge of switching simultaneously the input PW1 segment to the
output PW2, PW3, PW4 segments.
Note that a P2MP MS-PW may obviously transit through more than one S-
PE along its path.
Note that if the P2MP SS-PW case mandatory implies the use of P2MP
PSN tunnel (underlying layer) between the edge nodes, the P2MP MS-PW
does not imply such a requirement since each PW segment can be
supported over a P2P PSN tunnel. However as we will see hereafter,
the coexistence of both kind of PSN tunnel (P2P and P2MP) MUST be
considered, as described in Figure 3 where the P2MP PW3 segment is
supported over P2MP LSP.
5.2. P2MP MS-PW Underlying Layer
Figure 4 describes an example of P2MP MS-PW topology relying on a
combination of both P2P and P2MP LSPs as PSN tunnels. The PW tree is
composed of one Ingress PE (i1) and several Egress PEs (e1, e2, e3,
e4). The branch S-PEs are represented as b1, b2, b3, b4, b5. In that
case the traffic replication along the path of the PW tree is
performed at the PW level. For instance the branch S-PE b5 MUST
replicate incoming packets or data received from b2 and send them to
Egress T-PEs e3 and e4.
However giving the fact that some PW segments may be supported over a
P2MP LSP, the traffic replication along the path of these PW segments
can be performed as well at the underlying LSP level.
Figure 4 describes the case where each segment is supported over a
P2P LSP except for the b1-b3 and b1-b4 segments which are conveyed
over a P2MP LSP on this section.
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i1
/ \
b1 b2
/ \
/ \
/\ \
/ \ \
b3 b4 b5
/ \ / \
e1 e2 e3 e4
Figure 4 Example of P2P and P2MP underlying Layer for P2MP MS-PW
Depending on the Traffic-Engineering requirements, the P2MP PSN may
be signaled with P2MP RSVP-TE [P2MP-RSVP-TE or MLDP [MLDP].
As for the P2MP SS-PW and for the same purpose the PHP (Penultimate
Hop Popping) must be deactivated on the P2MP LSP as described in 4.2.
5.3. P2MP MS-PW Signaling Requirements
5.3.1. PW Addresses Routing
The PW tree could be statically configured at the T-PEs and each S-PE
crossed. However it is RECOMMENDED to derive benefit from the use of
PW addresses routing procedures (AII addressing used as reachability
information) in order to allow dynamic PW tree setup based on
principles described in [DYN MS-PW].
5.3.2. P2MP MS-PW Setup Mechanisms
The requirements described in this section assume that a PW
addresses routing dissemination procedure allows to dynamically
update each T-PE and S-PE PW addresses routing table.
The P2MP MS-PW setup could be source or leaf-initiated. However it is
RECOMMENDED that the solution provides various optimization options
in the P2MP MS-PW construction (Traffic-Engineered P2MP MS-PW).
Since a PW segment belonging to the P2MP MS-PW MAY be supported over
a P2P LSP, the PW upstream label assignment mode is no longer
mandatory. However it is RECOMMENDED to use this mode to be able to
deal with configuration where P2MP LSP supports several PW segments.
5.3.3. Leaf Grafting/Pruning
Once the PW tree is setup, the solution MUST allow the addition or
removal of a leaf, or a subset of leaves to/from the existing tree,
without any impact on the PW tree (data and control planes) for the
remaining leaves.
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5.3.4. Explicit Routing
The P2MP MS-PW signaling solution MUST provide a means of
establishing arbitrary P2MP MS-PW, according to pre-computed and
configured S-PE paths as well as dynamically computed S-PE paths on
the Ingress PE.
To support setup of explicitly routed MS-PW tree, the signaling
solution SHOULD support some source-based control that can explicitly
define particular S-PE nodes as branch S-PEs for the PW tree.
The solution SHOULD let possible Explicit Path Loose Hops (to be
defined). Therefore the P2MP MS-PW MAY be partially specified with
only a subset of intermediate branch S-PEs.
5.4. Failure Reporting
The solution SHOULD rely on specific OAM mechanisms to detect a node
(T-PE and S-PE) or segment failure of a PW tree. The solution SHOULD
also support the ability to inform the Ingress T-PE of the failure as
well as to indicate the identity of affected Egress T-PEs and
associated leaves.
Based on these failure notifications the solution MUST allow the
Ingress T-PE to update the remaining Egress PEs and associated leaves
of the PW tree.
During the PW tree setup, a branch S-PE SHOULD be capable to inform
the upstream PEs, including the Ingress T-PE that a set of Egress T-
PEs and associated leaves are not reachable in accordance with the
local PW addresses routing table.
- A solution MUST support in-band OAM mechanism to detect failures:
unidirectional point-to-multipoint traffic failure.
- In case of failure, it SHOULD correctly report which leaf T-PEs and
branch S-PEs are affected. It SHOULD be realized by enhancing
existing unicast PW methods, such as VCCV for seamless and familiar
operation.
- A solution MAY support OAM message mapping at T-PE if failure
happens i.e., mapping AC service OAM between P2MP PW OAM. (This needs
more discussion)
5.5. Protection and Restoration
The solution SHOULD provide mechanisms to recover as fast as possible
following a failure event. The fast protection/recovery is typically
dedicated to P2MP applications sensitive to traffic disruption.
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Considering (i) a source-initiated PW tree setup and (ii) that a
local repair (PSN-tunnel or PW segment-based) is not feasible after a
failure event and that (iii) the PE upstream to the failure receives
by means of OAM mechanisms a message indicating that a subset of
Egress T-PEs are detached from the PW tree, the solution SHOULD allow
the upstream PE to re-compute the path to those particular Egress T-
PEs. If the upstream PE failed to compute an alternative path, the
procedure SHOULD be propagated upstream until the Ingress-PE is
reached.
It is also assumed that recovery procedures can be implemented at the
underlying P2P or P2MP LSP layer, using classic recovery techniques.
These procedures could be used to provide faster recovery time in
case of link or node failure affecting this layer.
A mechanism should be implemented to avoid race conditions between
recovery at the PSN level and recovery at the PW level.
5.6. Advertisement of P2MP Capability
The solution should be completely backward compatible with
the current PW standards. The solution should take into account the
capability advertisement and negotiation procedures for the T-PEs
implementing P2MP MS-PW endpoints and branch S-PEs.
Implementation of OAM mechanisms also implies the advertisement of PE
capabilities to support specific OAM features. The solution SHOULD
allow advertising P2MP OAM PW capabilities.
5.7. Scalability
In definition of solution for P2MP MS-PW a particular attention must
dedicated to scalability.
The solution MUST be designed to scale as well as linearly with an
increase in the number of leaves, Egress T-PEs, branch S-PEs. The
scalability issues MUST be addressed for the control plane (e.g.
addressing of PW endpoints, number of signaling sessions, etc) and
for data plane (e.g. duplication of PW segments, OAM mechanism, etc).
5.8. Order of Magnitude
This section will be filled in a future version.
Number of Egress T-PE per tree, TAII per Egress T-PE, S-PE crossed,
replication supported per S-PE, dynamicity (Leaf Grafting/Pruning)
required, etc.
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6. Manageability considerations
This section will be added in a future version.
7. Backward Compatibility
This section will be added in a future version.
8. Security Considerations
This section will be added in a future version.
9. IANA Considerations
This draft does not define any new protocol element, and hence does
not require any IANA action.
10. Acknowledgments
The authors thank the contributors of [RFC4461] since the structure
and content of this document were, for some sections, largely
inspired by [RFC4461].
Many thanks to JL Le Roux and A. Cauvin for the discussions, comments
and support.
The authors would like to thank Matthew Bocci, Andy Malis for their
valuable comments and suggestions.
11. References
11.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, March 1997.
[RFC3916] McPherson, D.,Pate, P., Xiao, X., "Requirements for
Pseudo-Wire Emulation Edge-to-Edge", September 2004
[RFC3985] Bryant, S., Pate, P. "PWE3 Architecture", March 2005
[RFC4461] Aggarwal, R., Farrel, A., Jork, M., Kamite, Y.,
Kullberg, A., Le Roux, JL., Malis, A., Papadimitriou,
D., Vasseur, JP., Yasukawa, S., "Signaling Requirements
for P2MP TE MPLS LSPs",April 2006
11.2. Informative References
[MS-PW REQ] Bitar, N., Bocci, M., and Martini, L., "Requirements
for inter domain Pseudo-Wires", Internet Draft, draft-
ietf-pwe3-ms-pw-requirements-03.txt, October 2006
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Internet Draft P2MP PW Requirements February 2007
[MS-PW ARCH] Bocci, M., and Bryant, S.,T., " An Architecture for
Multi-Segment Pseudo Wire Emulation Edge-to-Edge",
Internet Draft, draft-ietf-pwe3-ms-pw-arch-02.txt,
October 2006
[SEG PW] Martini et al, "Segmented Pseudo Wire", Internet
Draft, draft-ietf-pwe3-segmented-pw-03.txt, October
2006
[VPLS MCAST REQ] Fang, L., Morin, T., Kamite, Y., Serbest, Y.,
"Requirements for Multicast Support in Virtual Private
LAN Services", Internet Draft, draft-ietf-l2vpn-vpls-
mcast-reqts-03.txt, Ocober 2006
[DYN MS-PW] Balus, F., Bocci, M., Martini, L., "Dynamic Placement
of Multi Segment Pseudo Wires", Internet Draft, draft-
ietf-pwe3-dynamic-ms-pw-02.txt, October 2006
[PW MCAST] Dong, J., Yang, Y., Zhang, H., "Pseudowire for
Supporting Multicast traffic", Internet Draft, draft-
ietf-pwe3-pw-mcast-00.txt, February 2006
[P2MP RSVP-TE] Aggarwal, R., Papadimitriou, D., Yasukawa, S.,
"Extensions to RSVP-TE for Point-to-Multipoint TE
LSPs", Internet Draft, draft-ietf-mpls-rsvp-te-p2mp-
06.txt, July 2006
[MLDP] Minei, I., Wijnands, I., Thomas, B., "Label
Distribution Protocol Extensions for Point-to-
Multipoint and Multipoint-to-Multipoint Label Switched
Paths", Internet Draft, draft-ietf-mpls-ldp-p2mp-02,
June 2006
Author's Addresses
Frederic Jounay
France Telecom
2, avenue Pierre-Marzin
22307 Lannion Cedex
FRANCE
Email: frederic.jounay@orange-ftgroup.com
Philippe Niger
France Telecom
2, avenue Pierre-Marzin
22307 Lannion Cedex
FRANCE
Email: philippe.niger@orange-ftgroup.com
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Internet Draft P2MP PW Requirements February 2007
Yuji Kamite
NTT Communications Corporation
Tokyo Opera City Tower
3-20-2 Nishi Shinjuku, Shinjuku-ku
Tokyo 163-1421
Japan
Email: y.kamite@ntt.com
Luca Martini
Cisco Systems, Inc.
9155 East Nichols Avenue, Suite 400
Englewood, CO, 80112
EMail: lmartini@cisco.com
Giles Heron
Tellabs
Abbey Place
24-28 Easton Street
High Wycombe
Bucks
HP11 1NT
UK
EMail: giles.heron@tellabs.com
Simon Delord
Uecomm
658 Church St
Richmond, VIC, 3121, Australia
E-mail: sdelord@uecomm.com.au
Lei Wang
Telenor
Snaroyveien 30
Fornebu 1331
Norway
Email: lei.wang@telenor.com
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Internet Draft P2MP PW Requirements February 2007
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