Network Working Group Seisho Yasukawa (NTT)
Internet Draft Dimitri Papadimitriou (Alcatel)
Jean Philippe Vasseur (Cisco)
Adrian Farrel (Old Dog) Yuji Kamite (NTT Communications)
Markus Jork (Avici) Rahul Aggarwal (Juniper)
Andrew G. Malis(Tellabs) Alan Kullberg (Motorola)
Expiration Date: March 2004 October 2003
Requirements for Point to Multipoint extension to RSVP-TE
<draft-ietf-mpls-p2mp-requirement-00.txt>
Status of this Memo
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Abstract
This document presents a set of requirements for Point-to-Multipoint
(P2MP) Traffic Engineering (TE) extensions to Multiprotocol Label
Switching (MPLS). It specifies functional requirements for RSVP-TE in
order to deliver P2MP applications over a MPLS TE infrastructure. It
is intended that potential solutions, that specify RSVP-TE procedures
for P2MP TE LSP setup, use these requirements as a guideline. It is
not intended to specify solution specific details in this document.
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It is intended that the requirements presented in this document are
not limited to the requirements of packet switched networks, but also
encompass the requirements of TDM, lambda and port switching networks
managed by Generalized MPLS (GMPLS) protocols. Protocol solutions
developed to meet the requirements set out in this document must be
equally applicable to MPLS and GMPLS.
Table of Contents
1. Introduction .................................................. 3
2. Definitions ................................................... 4
2.1 Acronyms .................................................. 4
2.2 Terminology ............................................... 4
2.3 Conventions ............................................... 5
3. Problem statements ............................................ 5
3.1 Motivation ................................................ 5
3.2 Requirements overview ..................................... 6
4. Application Specific Requirements ............................. 8
4.1 P2MP tunnel for IP multicast data ......................... 8
4.2 P2MP backbone network for IP multicast network ............ 9
4.3 Layer 2 Multicast Over MPLS ...............................10
4.4 VPN multicast network .....................................10
4.5 GMPLS network .............................................11
5. Requirements for P2MP capability exptension ...................12
5.1 P2MP LSP tunnels ..........................................12
5.2 P2MP explicit routing .....................................12
5.3 Explicit Path Loose Hops and Widely Scoped Abstract Nodes .13
5.4 P2MP LSP establishment, teardown, and modification
mechanisms ................................................14
5.5 Failure Reporting and Error Recovery ......................14
5.6 Record route of P2MP TE LSP tunnels .......................15
5.7 Call Admission Control (CAC) and QoS control mechanism
of P2MP LSP tunnels .......................................15
5.8 Rerouting of P2MP TE LSP ..................................16
5.9 IPv4/IPv6 support .........................................16
5.10 P2MP MPLS Label ..........................................16
5.11 Routing advertisement of P2MP capability .................17
5.12 Multi-Area/AS LSP ........................................17
5.13 P2MP MPLS management .....................................17
6. Security Considerations........................................17
7. Acknowledgements ..............................................17
8. References ....................................................18
9. Author's Addresses ............................................19
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1. Introduction
This document presents a set of requirements for Point-to-Multipoint
(P2MP) Traffic Engineering (TE) extensions to Multiprotocol Label
Switching (MPLS). It specifies functional requirements for RSVP-TE
[RFC3209] in order to deliver P2MP applications over a MPLS TE
infrastructure.
It is intended that potential solutions, that specify RSVP-TE
procedures for P2MP TE LSP setup, use these requirements as a
guideline. It is not intended to specify solution specific details
in this document.
It is intended that the requirements presented in this document are
not limited to the requirements of packet switched networks, but also
encompass the requirements of TDM, lambda and port switching networks
managed by Generalized MPLS (GMPLS) protocols. Protocol solutions
developed to meet the requirements set out in this document must be
equally applicable to MPLS and GMPLS.
Content Distribution (CD), Interactive multi-media (IMM), and VPN
multicast are applications that are best supported with multicast
capabilities.
One possible solution would be to setup multiple P2P TE LSPs, one
to each of the required egress LSRs. This requires replicating
incoming packets to all the P2P LSPs at the ingress LSR to
accommodate multipoint communication. This is sub-optimal. It
places the replication burden on the ingress LSR and hence has
very poor scaling characteristics. It also wastes bandwidth
resources, memory and MPLS (e.g. label) resources in the network.
Hence, to provide TE for a P2MP application in an efficient manner
in a large scale environemnt, P2MP TE mechanisms are required.
Existing MPLS P2P TE mechanisms have to be enhanced to support P2MP
TE LSP setup.
This should be achieved without running a multicast routing protocol
in the network core and with maximum re-use of the existing MPLS
protocols. A P2MP LSP will be setup with TE constraints and will
allow efficient packet replication at various branching points in
the network. RSVP-TE will be used for setting up a P2MP LSP with
enhancements to existing P2P TE LSP procedures. The P2MP TE LSP
setup mechanism will include the ability to add/remove receivers
to/from an existing P2MP LSP.
The problem statement is discussed in the following section. This
document discusses various applications that can use P2MP MPLS TE.
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Detailed requirements for the setup of a P2MP MPLS TE LSP using
RSVP-TE are described. Application specific requirements are also
described.
2. Definitions
2.1 Acronyms
P2P:
Point-to-point
P2MP:
Point-to-multipoint
2.2 Terminology
The reader is assumed to be familiar with the terminology in
[RFC3031] and [RFC3209].
P2MP TE LSP:
A traffic engineered label switched path that has one unique
ingress LSR (also referred to as the root) and more than one
egress LSR (referred to as the leaf).
P2MP path:
The ordered set of LSRs and links that comprise the P2MP LSP.
sub-P2MP path:
A sub-P2MP path is a portion of a P2MP path starting at
a particular LSR that is a member of the P2MP path and includes
ALL downstream LSRs that are also members of the P2MP path.
ingress LSR:
It is responsible for initiating the signaling messages that set
up, modify and teardown the LSP
branch LSR:
A LSR that has more than one downstream LSR. A branch LSR receives
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a single MPLS frame, makes a duplicate of it, and sends each to
downstream interfaces.
graft LSR:
A LSR that is already a member of the P2MP path and is in
process of signaling a new sub-P2MP path.
prune LSR:
A LSR that is already a member of the P2MP path and is in
process of tearing down an existing sub-P2MP path.
egress LSR:
One of potentially many destinations of the P2MP LSP. Note
that in some P2MP paths, an egress LSR may also have one or more
downstream LSRs. Such an egress LSR may also be referred to
as a branch LSR.
2.3 Conventions
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 [5].
3. Problem Statement
3.1 Motivation
Content Distribution (CD), Interactive multi-media (IMM), and VPN
multicast are applications that are best supported with multicast
capabilities.
IP Multicast provides P2MP communication. However, there are no
Traffic Engineering (TE) capabilities or QoS guarantees with existing
IP multicast protocols. Note that Diff-serv (see [RFC2475],[RFC2597]
and [RFC3246]) combined with IP multicast routing is not sufficient
for P2MP applications for many of the same reasons that it is not
sufficient for unicast applications TE and constraint based routing
are required to enable and scale the efficient management of network
resources, mechanism to prevent congestion (including Call Admission
Function combined with explicit source routing, Diffserv), and to
enable sub-second rerouting around network failures. Furthermore
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there are no existing P2MP mechanisms for carrying layer 2 or
SONET/SDH multicast traffic over MPLS. TE capabilities are desirable
for both these applications.
One possible solution would be to setup multiple P2P TE LSPs, one to
each of the required egress LSRs. This requires replicating incoming
traffic to all the P2P LSPs at the ingress LSR to accommodate
multipoint communication. This is clearly sub-optimal. It places the
replication burden on the ingress LSR and hence has very poor scaling
characteristics. It also wastes bandwidth resources, memory and MPLS
(e.g. label) resources in the network.
Hence, to provide MPLS TE [RFC2702] for a P2MP application in an
efficient manner in a large scale environment, P2MP TE mechanisms are
required. Existing MPLS P2P TE mechanisms have to be enhanced to
support P2MP TE LSP setup.
3.2. Requirements Overview
This document is proposing requirements for the setup of P2MP TE
LSPs. This should be achieved without running a multicast routing
protocol in the network core and with maximum re-use of the existing
MPLS protocols. Note that the use of MPLS forwarding to carry the
multicast traffic may also be useful in the context of some network
design where it is being desired to avoid running some multicast
routing protocol like PIM [PIM-SM] or BGP (which might be required
for the use of PIM).
A P2MP LSP will be setup with TE constraints and will allow efficient
MPLS packet replication at various branching points in the network.
RSVP-TE will be used for setting up a P2MP LSP with enhancements to
existing P2P TE LSP procedures.
The P2MP TE LSP setup mechanism will include the ability to
add/remove receivers to/from an existing P2MP LSP and should support
all the TE LSP management procedures defined for P2P TE LSP
(like the non disruptive rerouting (so called "Make before break"
procedure).
The computation of P2MP TE paths is implementation dependent and is
beyond the scope of the solutions that are built with this document
as a guideline.
The MPLS WG will specify how to build solutions for the setup a P2MP
TE LSP. The usage of those solutions will be application dependent
and is out of the scope of this draft.
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Consider the following figure.
Source 1 (S1)
|
I-LSR1
| |
| |
R2----E-LSR3--LSR1 LSR2---E-LSR2--Receiver 1 (R1)
| :
R3----E-LSR4 E-LSR5
| :
| :
R4 R5
Figure 1.
The above figure shows I(Ingress)-LSR1, E(Egress)-LSR2, E-LSR3 and
E-LSR4. I-LSR1 is attached to a traffic source that is generating
traffic for a P2MP application. E-LSR2, E-LSR3 and E-LSR4 are
attached to receivers that are interested in receiving traffic for
the application. The following are the objectives that we wish to
achieve:
a) A P2MP TE LSP path information which satisfies various
constrains is pre-determined and supplied to ingress I-LSR1.
Typical constraints are bandwidth requirements, resource class
affinities, fast rerouting, preemption, along with several
potential other constraints. There should not be any
restriction on the possibility to support the set of
constraints already defined for point to point TE LSPs.
b) Set up a P2MP TE LSP from I-LSR1 to E-LSR2, E-LSR3 and E-LSR4
using the path information which could have been computed by
some off-line or on-line algorithms.
c) In this case, the branch LSR1 should replicate incoming packets
and send them to E-LSR3 and E-LSR4.
d) The P2MP TE LSP should be setup by enhancing existing RSVP-TE
P2P procedures and without any requirement for multicast
routing protocol in the network core.
e) The solution should provide the ability to gracefully modify
P2MP TE LSP (i.e add/remove some part of the p2mp TE LSP
without requiring to entirely tearing down or setting up a
completely new p2mp TE LSP). Such operations should be
performed in a non traffic disruptive fashion. In this case,
a sub-P2MP path LSR2->E-LSR5 is grafted and pruned based on
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traffic destination change.
4. Application Specific Requirements
This section describes some of the applications that P2MP MPLS
TE is applicable to along with application specific requirements,
if any.
4.1 P2MP tunnel for IP multicast data
One typical scenario is to use P2MP TE LSPs as P2MP tunnels of
multicast data traffic (e.g. IP mcast). In this scenario, a P2MP LSP
tunnel is established between an ingress LSR which accomodates
IP multicast source and several egress LSRs which accomodate several
IP multicast receivers. Instead of using IP multicast routing
protocol in the network core, a P2MP LSP tunnel is established over
the network and IP multicast data are tunnelled from an ingress LSR
node to multiple egress leaf LSRs with the data replication at the
branch LSRs in the network core. Figure 2 shows this example.
Note that a P2MP TE LSP can be established over multiple AREAs/ASs.
Mcast Source
|
+---------------I-LSR0----------------+
| | |
| LSR0 +----E-LSR2---R2
| / \ / |
R1---E-LSR1---LSR2-----LSR1 LSR3----LSR4----E-LSR3---R3
| / \ \ |
| / \ +----E-LSR4---R4
+-------B-LSR1---------B-LSR2---------+
+-------- / ------++------ \ ---------+
| | || |
R5---E-LSR5--------LSR5 || IPmcast Network |
| / \ || |
+-E-LSR6---E-LSR7-++----MR0--MR1------+
| | | |
R6 R7 R8 R9
Figure 2
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4.2 P2MP backbone network for IP multicast network
In this scenario, P2MP TE LSPs are utilized to construct a P2MP
backbone network for multicast network (e.g. IPmcast network). Each
IP multicast access networks is interconnected by a P2MP TE LSP.
A P2MP LSP is established from an ingress LSR which accomodates IP
multicast network that has a Mcast Source to multiple egress LSRs
which accomodate an IP multicast network. In this scenario,
ingress/egress LSRs placed at the edge of multicast network must
handle IP multicast routing protocol. This means that each
ingress/egress LSR exchanges IP multicast routing messages as
neighbour router. Figure 3 shows a network example of this scenario.
A P2MP LSP is established from a I-LSR1 to E-LSR2, E-LSR3, E-LSR4 and
each ingress/egress LSR exchanges the multicast routing messages each
other.
As specified in the section on the problem statement it should be
possible for a solution to add/remove egress LSRs to/from the
P2MP MPLS TE LSP. IP multicast group membership distribution between
the egress LSRs may change frequently. This in turn may require a
potential P2MP MPLS TE solution, that is suitable for IP multicast,
to handle additions/deletions of egress LSRs at a rapid rate.
It is recommended to support a message exchange mechanism on top of
P2MP LSP setup mechanism to support multicast (S, G) Join/ Leave and
to allow the ingress LSR to hold sufficient information in order to
optimise multicast FEC on sender nodes.
Though several schemes exist to handle this scenario, these are out
of scope of this document. This document only describes requirements
to setup a P2MP TE LSP.
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Mcast Source
|
+-----MR-----+
| | |
| MR |
+------|-----+
+---------------I-LSR1----------------+
| // ||| \\ |
| // ||| \\ |
| // |LSR| \\ |
| ___//____/|_____\\____ |
| / // ||| \\ \ |
| | // ||| \\ | |
+-----E-LSR2----E-LSR3-----E-LSR4-----+
+---- / ---++------|------++--- \ ----+
| | || | || | |
R1---MR---MR || MR || MR__ |
| / \ || / \ || / \ \MR---R8
+--MR--MR--++----MR--MR---++--MR--MR--+
| | | | | |
R2 R3 R4 R5 R6 R7
Figure 3
4.3 Layer 2 Multicast Over MPLS
Existing layer 2 networks offer multicast video services. These are
typically carried using layer 2 NBMA technology such as ATM or
layer 2 BA technology such as Ethernet. It may be desirable to
deliver these layer 2 multicast services over a converged MPLS
infrastructure where P2MP TE LSPs are used instead.
4.4 VPN multicast network
In this scenario, P2MP TE LSPs are utilized to construct a provider
network which can deliver VPN multicast service(s) to its customers.
A P2MP TE LSP is established between all the PE routers which
accommodate the customer private network(s) that handle the IP
multicast packets. Each PE router must handle VPN instance.
For example, in Layer3 VPN like BGP/MPLS based IP VPN
[BGP/MPLS IP VPNs], this means that each PE router must handle both
private multicast VRF tables and common multicast routing and
forwarding table. And each PE router exchanges private multicast
routing information between the corresponding PE routers. It is
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desirable that P2MP MPLS TE can be used for Layer3 VPN's data
transmission.
Another example is Layer2 VPN that supports multipoint
LAN connectivity service. In Ethernet network environment, IP
multicast data is flooded to the appropriate Ethernet port(s). In
Ethernet multipoint L2 VPN service provided by MPLS, this function is
achieved by switching MPLS encapsulated frames towards the relevant
PE nodes. But if existing P2P TE LSPs are used as tunnels between
PEs, any ingress PE must duplicate the frames and the send them to
the corresponding PEs. This means data stream is flooded just from
ingress PE, which will waste provider's network resources.
So, for Layer 2 VPNs, it is desirable that P2MP MPLS TE LSPs are used
for data transmission instead of P2P MPLS TE LSPs, contributing in
turn to savings of network resources.
4.5 GMPLS Network
GMPLS supports only P2P TE-LSPs just like MPLS. GMPLS enhances MPLS
to support four new classes of interfaces Layer-2 Switch Capable
(L2SC), Time-Division Multiplex (TDM), Lambda Switch Capable (LSC)
and Fiber-Switch Capable (FSC) in addition to Packet Switch Capable
(PSC) already supported by MPLS. All of these interface classes have
so far been limited to P2P TE LSPs (see [RFC 3473] and [RFC 3471]).
The requirement for P2MP services for non-packet switch interfaces
is similar to that for PSC interfaces. In particular, cable
distribution services such as video distribution are prime candidates
to use P2MP features. Therefore, it is a requirement that all the
features/mechanisms (and protocol extensions) that will be defined to
provide MPLS P2MP TE LSPs will be equally applicable to P2MP PSC and
non-PSC TE-LSPs.
This also means that solutions for MPLS P2MP TE-LSPs when applied
to GMPLS P2MP PSC and non-PSC TE-LSPs shall be backward and
forward compatible with the other features of GMPLS including:
o control and data plane separation (IF_ID RSVP_HOP and
IF_ID ERROR_SPEC),
o full support of numbered and unnumbered TE links (see [RFC 3477]
and [GMPLS-ROUTING]),
o use of the GENERALIZED_LABEL_REQUEST and the GENERALIZED_LABEL
(C-Type 2 and 3) in conjunction with the LABEL_SET and the
ACCEPTABLE_LABEL_SET object,
o processing of the ADMIN_STATUS object,
o processing of the PROTECTION object,
o support of Explicit Label Control,
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o processing of the Path_State_Removed Flag,
o handling of Graceful Deletion procedures.
In addition, since non-PSC TE-LSPs may have to be processed in
environments where the "P2MP capability" could be limited, specific
constraints may also apply during the P2MP TE Path computation. Being
technology specific, these constraints are outside the scope of this
document. However, technology independent constraints (i.e.
constraints that are applicable independently of the LSP class)
should be allowed during P2MP TE LSP message processing. It has to be
emphasized that path computation and management techniques shall be
as close as possible than those being used for PSC P2P and P2MP TE
LSPs.
5. Requirements for P2MP capability extension
5.1 P2MP LSP tunnels
The P2MP RSVP-TE extensions MUST be applicable to signaling LSPs
of different traffic types. For example, it must be possible to
signal a P2MP LSP to carry any kind of payload being packet or
non-packet based (including frame, cell, TDM un/structured, etc.)
Carrying IP multicast or Ethernet traffic within a P2MP tunnel are
typical examples.
As with P2P MPLS technology[RFC3031], traffic is classified with
FEC in this extension. All packets which belong to a particular FEC
and which travel from a particular node MUST follow the same P2MP
path.
In order to scale to a large number of branches, P2MP TE LSPs should
be identified by unique identifier that is constant for the whole LSP
regardless of the number of branches and/or leaves. Therefore, the
identification of the P2MP session by its destination addresses is
not adequate.
5.2 P2MP explicit routing
Various optimizations in P2MP path formation need to be applied to
meet various needs such as bandwidth guarantees, delay requirements,
and minimization of the total P2MP path cost.
The P2MP TE solution therefore MUST provide a means of establishing
arbitrary P2MP paths. Figure 4 shows two typical examples.
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A A
| / \
B B C
| / \ / \
C D E F G
| / \ / \/ \ / \
D--E*-F*-G*-H*-I*-J*-K*--L H I J KL M N O
Steiner P2MP path SPF P2MP path
Figure 4 Examples of P2MP LSP topology
One example is Steiner[STEINER] P2MP path (Cost minimum P2MP path).
This P2MP path is suitable for constructing cost minimum P2MP path.
To realize this P2MP path, several intermediate LSRs must be both
MPLS data terminating LSR and transit LSR (LSR E, F, G, H, I, J, K,
in the figure). This means that the LSR must perform both label
swapping and popping at the same time. Therefore, the P2MP TE
solution MUST support a mechanism that can setup this kind of
terminate LSR between a ingress LSR and egress LSRs.
Another example is CSPF (Constraint Shortest Path Fast) P2MP path. By
some metric (which can be set upon any specific criteria like the
delay, bandwidth, a combination of those), one can calculate a cost
minimum P2MP path. This P2MP path is suitable for carrying real time
traffic.
To support explicit setup of any reasonable P2MP path shape, a P2MP
TE solution must support some form of explicit source-based control
of the P2MP path. This can be used by the ingress LSR to setup the
P2MP LSP. Being implementation specific (more precisely dependent of
the data structure specific representation and its processing), the
detailed method for controlling the P2MP TE LSP topology depends on
how the control plane represents the P2MP TE LSP data plane entity.
For instance, a P2MP TE LSP can be simply represented by its
individual branches or as a whole. Here also, effectiveness of the
potential solutions is left outside the scope of this document.
In any case, it is expected that this control must be driven by the
ingress LSR.
5.3 Explicit Path Loose Hops and Widely Scoped Abstract Nodes
A P2MP path is completely specified if all of the required
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branches and hops between a sender and leaf LSR are indicated.
A P2MP path is partially specified if only a subset of intermediate
branches and hops are indicated. This may be achieved using
loose hops in the explicit path, or using widely scoped abstract
nodes such as IPv4 prefixes shorter than 32 bits or AS numbers.
A partially specified P2MP path may be particularly useful in
inter-area and inter-AS situations.
Protocol solutions SHOULD include a way to specify loose
hops and widely scoped abstract nodes in the explicit source-
based control of the P2MP path as defined in the previous
section. Where this support is provided, protocol solutions
MUST allow downstream LSRs to apply further explicit
control to the P2MP path to resolve a partially specified path
into a (more) completely specified path.
Protocol solutions MUST allow the P2MP path to be completely
specified at the ingress where sufficient information exists to allow
the full path to be computed.
In all cases, the egress nodes of the P2MP LSP must be fully
specified.
5.4 P2MP LSP establishment, teardown, and modification mechanisms
The P2MP TE solution must support large scale P2MP TE LSPs
establishment and teardown in a scalable manner.
In addition to whole P2MP TE LSP establishment and teardown
mechanism, it SHOULD implement partial P2MP path modification
mechanism.
For the purpose of adding sub-P2MP TE LSPs for existing P2MP TE LSP,
the extension SHOULD support grafting mechanism. For the purpose of
deleting a sub-P2MP TE LSPs from existing P2MP TE LSP, the extension
SHOULD support pruning mechanism.
It is RECOMMENDED that these grafting and pruning operations do not
cause any additional processing in nodes except along the path to the
grafting and pruning node and its downstream nodes.
5.5 Failure Reporting and Error Recovery
Failure events may cause egress nodes or sub-P2MP LSPs to become
detached from the P2MP LSP. These events must be reported upstream as
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for a P2P LSP.
Protection and recovery techniques SHOULD be applied to the LSP to
build new sub-P2MP LSPs or use backup sub-P2MP LSPs to restore the
data to the severed egress nodes.
The report of the failure of delivery to fewer than all of the egress
nodes SHOULD NOT cause automatic teardown of the P2MP LSP. That is,
while some egress nodes remain connected to the P2MP path it should
be a matter of local policy at the ingress whether the P2MP LSP is
retained.
When all egress node downstreams of a branch node have become
disconnected from the P2MP path, and the branch node is unable to
restore connectivity to any of them through recovery or protection
mechanisms, the branch node MAY remove itself from the P2MP path.
Since the faults that severed the various downstream egress nodes
from the P2MP path may be disperate, the branch node MUST report all
such errors to its upstream neighbor.
5.6 Record route of P2MP TE LSP tunnels
Being able to identify the established topology of P2MP LSP is very
important for various purpose:Management, operation of some local
recovery mechanism like Fast Reroute [FRR]. A network operator uses
this information to manage P2MP LSP. Therefore, topology information
MUST be collected and updated after P2MP LSP establishment and
modification process.
For this purpose, conventional Record Route mechanism is useful.
As with other conventional mechanism, this information should be
forwarded upstream towards the sender node. The P2MP TE solution MUST
support a mechanism which can collect and update P2MP path topology
information after P2MP LSP establishment and modification process.
It is RECOMMENDED that those information are collected in a data
format by which the sendor node can recognize the P2MP path topology
without involving some complicated data calculation process.
5.7 Call Admission Control (CAC) and QoS Control mechanism
of P2MP LSP tunnels
P2MP LSP share network resource with P2P LSP. Therefore it is
important to use CAC and QoS as P2P LSP for easy and scalable
operation.
In particular, it should be highlighted that because
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mutliacst traffic cannot make use of point to point TE LSP, multicast
traffic cannot be easily taken into account by point to point in
order to perform CAC. The use of P2MP TE LSP will now allow for an
accounting of the unicast and multicast traffic for bandwidth
reservation.
P2MP TE solution MUST both supports FF and SE reservation style.
P2MP TE solution MUST be applicable to Diffserv-enabled network
that can provide consistent QoS control in P2MP LSP traffic.
This solution SHOULD also satisfy DS-TE requirement [RFC3564] and
interoprable smoothly with current P2P DS-TE protocol specification.
5.8 Rerouting of P2MP TE LSP
The detection of a more optical path and network resource failure(s)
(such as link(s) and node(s)) are examples of situation where P2MP TE
LSP re-routing is needed. While re-routing is in progress, an
important requirement is avoiding traffic disruption. An additional
requirement is avoiding double bandwidth reservation (over the common
parts between the old and new LSP) through the use of resource
sharing. Make-before-break (see [RFC 3209]) delivers simultaneously a
solution to these requirements.
Make-Before-Break MUST be supported for a P2MP TE LSP to ensure
that there is no traffic disruption when the P2MP TE LSP is rerouted.
And a P2MP TE solution MUST support P2MP fast rerouting mechanism
to handle P2MP applications sensitive to traffic disruption.
5.9 IPv4/IPv6 support
A P2MP TE solution MUST be applicable to IPv4/IPv6.
5.10 P2MP MPLS Label
A P2MP TE solution MUST support establishment of both P2P and
P2MP TE LSP and MUST NOT impede the operation of P2P LSPs within
the same network. A P2MP TE solution MUST be specified in such
a way that it allows P2MP and P2P LSPs to be signaled on the
same interface. Labels for P2MP TE LSPs and P2P TE LSPs MAY be
assigned from shared or dedicated label space(s). Label space
shareability is implementation specific.
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5.11 Routing advertisement of P2MP capability
This document has identified several high-level requirements for
enhancements to routing protocols to support P2MP MPLS.
These are needed to facilitate the computation of P2MP paths using TE
constraints so that explicit source-control may be applied to the LSP
paths as they are signaled through the network.
These requirements include but not restricted to:
- the ability of an LSR to support branching
- the ability of an LSR to act as an egress and a branch for the
same LSP.
The applicability of these requirements is for further study.
These requirements are developed in a separate document.
5.12 Multi-Area/AS LSP
P2MP TE solution SHOULD support multi-Area/AS LSP.
5.13 P2MP MPLS management
The MPLS MIB should be enhanced to provide P2MP TE LSP management.
P2MP TE LSPs MUST have a unique identifier whose definition MAY be
partially or entirely shared with P2P TE LSP identifiers used for
management purposes.
6. Security Considerations
Security considerations will be addressed in a future revision of
this document.
7. Acknowledgements
The authors would like to thank George Swallow, Ichiro Inoue and
Dean Cheng for his review and suggestion of an earlier draft of this
document.
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8. References
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan,
V. and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP Tunnels",
RFC 3209, December 2001.
[RFC3031] Rosen, E., Viswanathan, A. and R. Callon, "Multiprotocol
Label Switching Architecture", RFC 3031, January 2001.
[RFC2475] Blake, S., Black, D., Carlson, M., Davies, E., Wang, Z.
and W. Weiss, "An Architecture for Differentiated Services", RFC
2475, December 1998.
[RFC2597] Heinanen, J., Baker, F., Weiss, W. and J. Wroclawski,
"Assured Forwarding PHB Group", RFC 2597, June 1999.
[RFC3246] Davie, B., Charny, A., Bennet, J.C.R., Benson, K., Le
Boudec, J.Y., Davari, S., Courtney, W., Firioiu, V. and D. Stiliadis,
"An Expedited Forwarding PHB (Per-Hop Behavior)", RFC 3246,
March 2002.
[RFC2362] D. Estrin, D. Farinacci, A. Helmy, D. Thaler, S. Deering,
M. Handley, V. Jacobson, C. Liu, P. Sharma, L. Wei, "Protocol
Independent Multicast-Sparse Mode (PIM-SM): Protocol Specification.",
RFC 2362, June 1998.
[RFC2702] D. Awduche, J. Malcolm, J. Agogbua, M. O'Dell, J. McManus,
"Requirements for Traffic Engineering Over MPLS", RFC2702,
September 1999
[PIM-SM] B. Fenner, M. Hadley, H. Holbrook, I. Kouvelas, "Protocol
Independent Multicast - Sparse Mode (PIM-SM):Protocol Specification
(Revised)", draft-ietf-pim-sm-v2-new-08.txt, October 2003.
[BGP/MPLS IP VPNs] E. Rosen, Y.Rekhter, Editor, "BGP/MPLS IP VPNs",
draft-ietf-l3vpn-rfc2547bis-01.txt, September 2003
[RFC3471] Berger, L., Editor, "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling Functional Description", RFC 3471,
January 2003.
[RFC3473] Berger, L., Editor, "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling - Resource ReserVation Protocol-Traffic
Engineering (RSVP-TE) Extensions", RFC 3473, January 2003.
[RFC3477] K. Kompella, Y. Rekhter, "Signalling Unnumbered Links in
Resource ReSerVation Protocol -Traffic Engineering (RSVP-TE)",
RFC3477, January 2003.
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[GMPLS-ROUTING] K. Kompella, Y. Rekhter, Editor, "Routing
Extensions in Support of Generalized Multi-Protocol Label Switching",
draft-ietf-ccamp-gmpls-routing-08.txt, October 2003.
[STEINER] H. Salama, et al., "Evaluation of Multicast Routing
Algorithm for Real-Time Communication on High-Speed Networks,"
IEEE Journal on Selected Area in Communications, pp.332-345, 1997
[DJIKSTRA] E. W. Djikstra, "A note on two problem in connection with
graphs," Numerische Mathematik, vol.1, pp.269-271, 1959
[IPMCAST-MPLS] D. Ooms, B. Sales, W. Livens, A. Acharya, F. Griffoul
and F. Ansari, "Overview of IP Multicast in a Multi-Protocol Label
Switching (MPLS) Environment", RFC3353, August 2002.
[FRR] P. Pan, D. Gan, G. Swallow, J. P. Vasseur, D. Cooper,
A. Atlas, M. Jork,"Fast Reroute Extensions to RSVP-TE for LSP
Tunnels", draft-ietf-mpls-rsvp-lsp-fastreroute-03.txt, July 2003
[RFC3564] F. Le Faucheur, W. Lai, "Requirements for Support of
Differentiated Services-aware MPLS Traffic Engineering", RFC3564,
July 2003
[OSPF-TE] D. Katz, D. Yeung, K. Kompella, "Traffic Engineering
Extensions to OSPF Version 2", draft-katz-yeung-ospf-traffic-08.txt,
September 2002
[IS-IS-TE] Henk Smit, Tony Li, "IS-IS extensions for Traffic
Engineering", draft-ietf-isis-traffic-04.txt, December 2002
9. Author's Addresses
Seisho Yasukawa
NTT Network Service Systems Laboratories, NTT Corporation
9-11, Midori-Cho 3-Chome
Musashino-Shi, Tokyo 180-8585 Japan
Phone: +81 422 59 4769
EMail: yasukawa.seisho@lab.ntt.co.jp
Dimitri Papadimitriou (Alcatel)
Francis Wellensplein 1,
B-2018 Antwerpen, Belgium
Phone : +32 3 240 8491
EMail: dimitri.papadimitriou@alcatel.be
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JP Vasseur
Cisco Systems, Inc.
300 Beaver Brook Road
Boxborough , MA - 01719
USA
Email: jpv@cisco.com
Yuji Kamite
NTT Communications Corporation
Innovative IP Architecture Center,
Tokyo Opera City Tower 21F,
20-2, 3-chome, Nishi-Shinjuku, Shinjuku-ku,
Tokyo, 163-1421, Japan.
EMail: y.kamite@ntt.com
Rahul Aggarwal
Juniper Networks
1194 North Mathilda Ave.
Sunnyvale, CA 94089
Email: rahul@juniper.net
Alan Kullberg
Motorola Computer Group
120 Turnpike Rd.
Southborough, MA 01772
Email: alan.kullberg@motorola.com
Adrian Farrel
Old Dog Consulting
Phone: +44 (0) 1978 860944
EMail: adrian@olddog.co.uk
Markus Jork
Avici Systems
101 Billerica Avenue
N. Billerica, MA 01862
email: mjork@avici.com
phone: +1 978 964 2142
Andrew G. Malis
Tellabs
2730 Orchard Parkway
San Jose, CA 95134
Phone: +1 408 383 7223
Email: andy.malis@tellabs.com
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