Internet Engineering Task Force Q. Zhao, Ed.
Internet-Draft Huawei Technology
Intended Status: Standards Track Daniel King, Ed.
Expires: November 25, 2010 Old Dog Consulting
May 25, 2010
Extensions to the Path Computation Element Communication Protocol
(PCEP) for Point-to-Multipoint Traffic Engineering Label Switched Paths
draft-ietf-pce-pcep-p2mp-extensions-11.txt
Abstract
Point-to-point Multiprotocol Label Switching (MPLS) and Generalized
MPLS (GMPLS) Traffic Engineering Label Switched Paths (TE LSPs) may
be established using signaling techniques, but their paths may first
need to be determined. The Path Computation Element (PCE) has been
identified as an appropriate technology for the determination of the
paths of P2MP TE LSPs.
This document describes extensions to the PCE communication Protocol
(PCEP) to handle requests and responses for the computation of paths
for P2MP TE LSPs.
Status of this Memo
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This Internet-Draft will expire on May 25, 2010.
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Copyright Notice
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Requirements Language
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 RFC 2119 [RFC2119].
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . .3
1.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . .4
2. Requirements . . . . . . . . . . . . . . . . . . . . . . . . .5
3. Protocol Procedures and Extensions . . . . . . . . . . . . . .6
3.1. P2MP Capability Advertisement . . . . . . . . . . . . . .6
3.1.1. P2MP Computation TLV in the Existing PCE Discovery
Protocol . . . . . . . . . . . . . . . . . . . . . . .6
3.1.2. Open Message Extension . . . . . . . . . . . . . . . .6
3.2. Efficient Presentation of P2MP TE LSPs . . . . . . . . . .7
3.3. P2MP Path Computation Request/Reply Message Extensions . .8
3.3.1. The Extension of the RP Object . . . . . . . . . . . .8
3.3.2. The New P2MP END-POINTS Object . . . . . . . . . . . .9
3.4. Request Message Format . . . . . . . . . . . . . . . . . .11
3.5. Reply Message Format . . . . . . . . . . . . . . . . . . .11
3.6. P2MP Objective Functions and Metric Types . . . . . . . .12
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3.6.1. New Objective Functions . . . . . . . . . . . . . . .12
3.6.2. New Metric Object Types . . . . . . . . . . . . . . .13
3.7. Non-Support of P2MP Path Computation. . . . . . . . . . .13
3.8. Non-Support by Back-Level PCE Implementations. . . . . . .13
3.9. P2MP TE Path Reoptimization Request . . . . . . . . . . .14
3.10. Adding and Pruning Leaves to the P2MP Tree . . . . . . . .14
3.11. Discovering Branch Nodes . . . . . . . . . . . . . . . . .17
3.11.1 Branch Node Object . . . . . . . . . . . . . . . . . .17
3.12. Synchronization of P2MP TE Path Computation Requests . . .18
3.13. Request and Response Fragmentation . . . . . . . . . . . .19
3.13.1. Request Fragmentation Procedure . . . . . . . . . . .19
3.13.2. Response Fragmentation Procedure . . . . . . . . . . .19
3.13.3. Fragmentation Examples . . . . . . . . . . . . . . . .19
3.14. UNREACH-DESTINATION Object . . . . . . . . . . . . . . . .20
3.15. P2MP PCEP Error Object and Types . . . . . . . . . . . . .21
3.16. PCEP NO-PATH Indicator . . . . . . . . . . . . . . . . . .22
4. Manageability Considerations . . . . . . . . . . . . . . . . .22
4.1. Control of Function and Policy . . . . . . . . . . . . . .23
4.2. Information and Data Models . . . . . . . . . . . . . . .23
4.3. Liveness Detection and Monitoring . . . . . . . . . . . .23
4.4. Verifying Correct Operation . . . . . . . . . . . . . . .23
4.5. Requirements on Other Protocols and Functional
Components . . . . . . . . . . . . . . . . . . . . . . . .23
4.6. Impact on Network Operation . . . . . . . . . . . . . . .24
5. Security Considerations . . . . . . . . . . . . . . . . . . .24
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . .24
6.1. PCEP TLV Type Indicators . . . . . . . . . . . . . . . . .25
6.2. Request Parameter Bit Flags . . . . . . . . . . . . . . .25
6.3. Objective Functions . . . . . . . . . . . . . . . . . . .25
6.4. Metric Object Types . . . . . . . . . . . . . . . . . . .25
6.5. PCEP Objects . . . . . . . . . . . . . . . . . . . . . . .25
6.6. PCEP Error Objects and Types . . . . . . . . . . . . . . .26
6.7. PCEP NO-PATH Indicator . . . . . . . . . . . . . . . . . .27
6.8. SVEC Object Flag . . . . . . . . . . . . . . . . . . . .27
6.9. OSPF PCE Capability Flag . . . . . . . . . . . . . . . .28
7. Acknowledgement's . . . . . . . . . . . . . . . . . . . . . .28
8. References . . . . . . . . . . . . . . . . . . . . . . . . . .28
8.1. Normative References . . . . . . . . . . . . . . . . . . .28
8.2. Informative References . . . . . . . . . . . . . . . . . .29
9. Authors' Addresses . . . . . . . . . . . . . . . . . . . . . .30
9.1. Contributors . . . . . . . . . . . . . . . . . . . . . . .31
1. Introduction
The Path Computation Element (PCE) defined in [RFC4655] is an entity
that is capable of computing a network path or route based on a
network graph, and applying computational constraints. A Path
Computation Client (PCC) may make requests to a PCE for paths to be
computed.
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[RFC4875] describes how to set up point-to-multipoint (P2MP) Traffic
Engineering Label Switched Paths (TE LSPs) for use in Multiprotocol
Label Switching (MPLS) and Generalized MPLS (GMPLS) networks.
The PCE has been identified as a suitable application for the
computation of paths for P2MP TE LSPs [RFC5671].
The PCE communication protocol (PCEP) is designed as a communication
protocol between PCCs and PCEs for point-to-point (P2P) path
computations and is defined in [RFC5440]. However, that
specification does not provide a mechanism to request path
computation of P2MP TE LSPs.
A P2MP LSP is comprised of multiple source-to-leaf (S2L) sub-LSPs.
These S2L sub-LSPs are set up between ingress and egress LSRs and are
appropriately overlaid to construct a P2MP TE LSP. During path
computation, the P2MP TE LSP may be determined as a set of S2L sub-
LSPs that are computed separately and combined to give the path of
the P2MP LSP, or the entire P2MP TE LSP may be determined as a P2MP
tree in a single computation.
This document relies on the mechanisms of PCEP to request path
computation for P2MP TE LSPs. One path computation request message
from a PCC may request the computation of the whole P2MP TE LSP, or
the request may be limited to a sub-set of the S2L sub-LSPs. In the
extreme case, the PCC may request the S2L sub-LSPs to be computed
individually with it being the PCC's responsibility to decide whether
to signal individual S2L sub-LSPs or combine the computation results
to signal the entire P2MP TE LSP. Hence the PCC may use one path
computation request message or may split the request across multiple
path computation messages.
1.1 Terminology
Terminology used in this document.
TE LSP: Traffic Engineered Label Switched Path.
LSR: Label Switching Router.
OF: Objective Function: A set of one or more optimization criteria
used for the computation of a single path (e.g., path cost
minimization), or for the synchronized computation of a set of paths
(e.g., aggregate bandwidth consumption minimization).
P2MP: Point-to-Multipoint.
P2P: Point-to-Point.
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This document also uses the terminology defined in [RFC4655],
[RFC4875], and [RFC5440].
2. Requirements
This section summarizes the PCC-PCE Communication Requirements for
P2MP MPLS-TE LSPs described in [PCE-P2MP-REQ]. The numbering system
corresponds to the requirement numbers used in [PCE-P2MP-REQ].
1. The PCC MUST be able to specify that the request is a P2MP path
computation request.
2. The PCC MUST be able to specify that objective functions are to be
applied to the P2MP path computation request.
3. The PCE MUST have the capability to reject a P2MP path request
and indicate non-support of P2MP path computation.
4. The PCE MUST provide an indication of non-support of P2MP path
computation by back-level PCE implementations.
5. A P2MP path computation request MUST be able to list multiple
destinations.
6. A P2MP path computation response MUST be able to carry the path
of a P2MP LSP.
7. It MUST be possible for a single P2MP path computation request or
response to be conveyed by a sequence of messages.
8. It MUST NOT be possible for a single P2MP path computation
request to specify a set of different constraints, traffic
parameters, or quality-of-service requirements for different
destinations of a P2MP LSP.
9. P2MP path modification and P2MP path diverse MUST be supported.
10. It MUST be possible to reoptimize existing P2MP TE LSPs.
11. It MUST be possible to add and remove P2MP destinations
from existing paths.
12. It MUST be possible to specify a list of applicable branch
nodes to use when computing the P2MP path.
13. It MUST be possible for a PCC to discover P2MP path computation
capability.
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14. The PCC MUST be able to request diverse paths when requesting a
P2MP path.
3. Protocol Procedures and Extensions
The following section describes the protocol extensions required to
satisfy the requirements specified in Section 2. (Requirements)
of this document.
3.1. P2MP Capability Advertisement
3.1.1. P2MP Computation TLV in the Existing PCE Discovery Protocol
[RFC5088] defines a PCE Discovery (PCED) TLV carried in an OSPF
Router Information LSA defined in [RFC4970] to facilitate PCE
discovery using OSPF. [RFC5088] specifies that no new sub-TLVs may be
added to the PCED TLV. This document defines a new flag in the OSPF
PCE Capability Flags to indicate the capability of P2MP computation.
Similarly, [RFC5089] defines the PCED sub-TLV for use in PCE
Discovery using IS-IS. This document will use the same flag
requested for the OSPF PCE Capability Flags sub-TLV
to allow IS-IS to indicate the capability of P2MP computation.
The IANA request for a shared OSPF and IS-IS P2MP capability flag
is documented in Section 6.9. (OSPF PCE Capability Flag) of this
document.
PCEs wishing to advertise that they support P2MP path computation
would set the bit (to be assigned by IANA) accordingly. PCCs that
do not understand this bit will ignore it (per [RFC5088] and
[RFC5089]). PCEs that do not support P2MP will leave the bit clear
(per the default behavior defined in [RFC5088] and [RFC5089]).
PCEs that set the bit to indicate support of P2MP path computation
MUST follow the procedures in Section 3.1.2. (The New P2MP END-POINTS
Object)to further qualify the level of support
3.1.2. Open Message Extension
Based on the Capabilities Exchange requirement described in
[PCE-P2MP-REQ]. If a PCE does not advertise its P2MP capability
during discovery, PCEP should be used to allow a PCC to discover
during the Open Message Exchange, which PCEs are capable of
supporting P2MP path computation.
To satisfy this requirement, we extend the PCEP OPEN object by
defining a new optional TLV to indicate the PCE's capability to
perform P2MP path computations.
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The allocation from the "PCEP TLV Type Indicators" sub-registry will
be assigned by IANA and the request is documented in Section 6.1.
(PCEP TLV Type Indicators). The description is "P2MP capable", the
length value is 2 bytes. The value field is set to default value 0.
The inclusion of this TLV in an OPEN object indicates that the sender
can perform P2MP path computations.
The capability TLV is meaningful only for a PCE so it will typically
appear only in one of the two Open messages during PCE session
establishment. However, in case of PCE cooperation (e.g.,
inter-domain), when a PCE behaving as a PCC initiates a PCE session
it SHOULD also indicate its path computation capabilities.
3.2. Efficient Presentation of P2MP LSPs
When specifying additional leaves, or optimizing existing P2MP TE
LSPs as specified in [PCE-P2MP-REQ], it may be necessary to pass
existing P2MP LSP route information between the PCC and PCE in the
request and reply message. In each of these scenarios, we need new
path objects for efficiently passing the existing P2MP LSP between
the PCE and PCC.
We specify the use of the Reservation Protocol Traffic Engineering
Extensions (RSVP-TE) Explicit Route Object (ERO) to encode the
explicit route of a TE LSP through the network. PCEP ERO sub-object
types correspond to RSVP-TE ERO sub-object types. The format and
content of the ERO object are defined in [RFC3209] and [RFC3473].
The Secondary Explicit Route Object (SERO) is used to specify the
explicit route of a S2L sub-LSP. The path of each subsequent S2L
sub-LSP is encoded in a P2MP_SECONDARY_EXPLICIT_ROUTE object SERO.
The format of the SERO is the same as an ERO defined in [RFC3209]
and [RFC3473].
The Secondary Recorded Route Object (SRRO) is used to record
the explicit route of the S2L sub-LSP. The class of the P2MP SRRO
is the same as the SRRO defined in [RFC4873].
The SERO and SRRO are used to report the route of an existing TE
LSP for which a reoptimization is desired. The format and content
of the SERO and SRRO are defined in [RFC4875].
A new PCEP object class and type are requested for SERO and SRRO.
Object-Class Value 26
Name SERO
Object-Type 1: SERO
2-15: Unassigned
Reference This.I-D
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Object-Class Value 27
Name SRRO
Object-Type 1: SRRO
2-15: Unassigned
Reference This.I-D
The IANA request is referenced in Section 6.5. (PCEP Objects).
Since the explicit path is available for immediate signaling by the
MPLS or GMPLS control plane, the meanings of all of the sub-objects
and fields in this object are identical to those defined for the ERO.
3.3. P2MP Path Computation Request/Reply Message Extensions
This document extends the existing P2P RP (Request Parameters) object
so that a PCC can signal a P2MP path computation request to the PCE
receiving the PCEP request. The END-POINT object is also extended
to improve the efficiency of the message exchange between PCC and PCE
in the case of P2MP path computation.
3.3.1. The Extension of the RP Object
The PCE path computation request and reply message will need the
following additional parameters to allow a receiving PCE to
identify that the request and reply message has been fragmented
across multiple messages, has been requested for a P2MP path and to
specify if the route is represented in the compressed or uncompressed
format.
This document adds the following flags to the RP Object:
The F bit is added to the flag bits of the RP object to indicate
to the receiver that the request is part of a fragmented request, or
is not a fragmented request.
o F ( RP fragmentation bit - 1 bit):
0: This indicates that the RP is not fragmented or it is the
last piece of the fragmented RP.
1: This indicates that the RP is fragmented and this is not
the last piece of the fragmented RP. The receiver
needs to wait for additional fragments until it receives
an RP with the same RP-ID and with the F bit is set to 0.
The N bit is added in the flag bits field of the RP object to signal
the receiver of the message that the request/reply is for P2MP or
not.
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o N ( P2MP bit - 1 bit):
0: This indicates that this is not PCReq/PCRep for P2MP.
1: This indicates that this is PCReq or PCRep message for P2MP.
The E bit is added in the flag bits field of the RP object to signal
the receiver of the message that the route is in the compressed
format or not. By default, the path returned by the PCE will use the
compressed format.
o E ( ERO-compression bit - 1 bit):
0: This indicates that the route is not in the compressed
format.
1: This indicates that the route is in the compressed format.
The IANA request is referenced in Section 6.2 (Request Parameter Bit
Flags) of this document.
3.3.2. The New P2MP END-POINTS Object
The END-POINTS object is used in a PCReq message to specify the
source IP address and the destination IP address of the path for
which a path computation is requested. To represent the end points
for a P2MP path efficiently, we define two new types of end-point
objects for the P2MP path:
o Old leaves whose path can be modified/reoptimized;
o Old leaves whose path must be left unchanged.
With the new END-POINTS object, the PCE path computation request
message is expanded in a way which allows a single request
message to list multiple destinations.
In total there are now 4 possible types of leaves in a P2MP request:
o New leaves to add (leaf type = 1)
o Old leaves to remove (leaf type = 2)
o Old leaves whose path can be modified/reoptimized (leaf type = 3)
o Old leaves whose path must be left unchanged (leaf type = 4)
A given END-POINTS object gathers the leaves of a given type. The
type of leaf in a given END-POINTS object is identified by the END-
POINTS object leaf type field.
Using the new END-POINTS object, the END-POINTS portion of a request
message for the multiple destinations can be reduced by up to 50% for
a P2MP path where a single source address has a very large number of
destinations.
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Note that a P2MP path computation request can mix the different types
of leaves by including several END-POINTS object per RP object as
shown in the PCReq Routing Backus-Naur Format (RBNF) [RFC5511] format
in Section 3.4. (Request Message Format).
The format of the new END-POINTS object body for IPv4 (Object-Type 3)
is as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Leaf type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source IPv4 address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination IPv4 address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ ... ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination IPv4 address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: The New P2MP END-POINTS Object Body Format for IPv4
The format of the END-POINTS object body for IPv6 (Object-Type 4) is
as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Leaf type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Source IPv6 address (16 bytes) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Destination IPv6 address (16 bytes) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ ... ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Destination IPv6 address (16 bytes) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: The New P2MP END-POINTS Object Body Format for IPv6
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The END-POINTS object body has a variable length. These are
multiples of 4 bytes for IPv4, and multiples of 16 bytes, plus 4
bytes, for IPv6.
3.4. Request Message Format
The PCReq message is encoded as follows using RBNF as defined in
[RFC5511].
Below is the message format for the request message:
<PCReq Message>::= <Common Header>
<request>
where:
<request>::= <RP>
<end-point-rro-pair-list>
[<OF>]
[<LSPA>]
[<BANDWIDTH>]
[<metric-list>]
[<IRO>]
[<LOAD-BALANCING>]
where:
<end-point-rro-pair-list>::=
<END-POINTS>[<RRO-List>][<BANDWIDTH>]
[<end-point-rro-pair-list>]
<RRO-List>::=<RRO>[<BANDWIDTH>][<RRO-List>]
<metric-list>::=<METRIC>[<metric-list>]
Figure 3: The Message Format for the Request Message
Note we preserve compatibility with the [RFC5440] definition of
<request>. At least one instance of <endpoints> MUST be present
in this message.
We have documented the IANA request for additional END-POINTS
Object-Types in Section 6.5 (PCEP Objects) of this document.
3.5. Reply Message Format
The PCRep message is encoded as follows using RBNF as defined in
[RFC5511].
Below is the message format for the reply message:
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<PCRep Message>::= <Common Header>
<response>
<response>::=<RP>
[<end-point-path-pair-list>]
[<NO-PATH>]
[<attribute-list>]
where:
<end-point-path-pair-list>::=
[<END-POINTS>]<path>[<end-point-path-pair-list>]
<path> ::= (<ERO>|<SERO>) [<path>]
<attribute-list>::=[<OF>]
[<LSPA>]
[<BANDWIDTH>]
[<metric-list>]
[<IRO>]
Figure 4: The Message Format for the Reply Message
The optional END-POINTS in the reply message is used to specify which
paths are removed, changed, not changed, or added for the request.
The path is only needed for the end points which are added or
changed.
If the E bit (ERO-Compress bit) was set to 1 in the request then the
path will be formed by an ERO followed by a list of SEROs.
Note that we preserve compatibility with the [RFC5440] definition of
<response> and the optional <end-point-path-pair-list> and <path>.
3.6. P2MP Objective Functions and Metric Types
3.6.1. New Objective Functions
Six objective functions have been defined in [RFC5541] for P2P path
computation.
This document defines two additional objective functions, namely SPT
(Shortest Path Tree) and MCT (Minimum Cost Tree) that apply to P2MP
path computation. Hence two new objective function codes have to be
defined.
The description of the two new objective functions is as follows.
Objective Function Code: 7 (suggested value, to be assigned by IANA)
Name: Shortest Path Tree (SPT)
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Description: Minimize the maximum source-to-leaf cost with respect to
a specific metric or to the TE metric used as the default metric when
the metric is not specified. (e.g. TE or IGP metric)
Objective Function Code: 8 (suggested value, to be assigned by IANA)
Name: Minimum Cost Tree (MCT)
Description: Minimize the total cost of the tree, that is the sum of
the costs of tree links, with respect to a specific metric or to the
TE metric used as the default metric when the metric is not
specified.
Processing these two new objective functions is subject to the rules
defined in [RFC5541].
3.6.2. New Metric Object Types
There are three types defined for the <METRIC> object in [RFC5440],
namely, the IGP metric, the TE metric and the Hop Count metric. This
document defines three additional types for the <METRIC> object: the
P2MP IGP metric, the P2MP TE metric, and the P2MP hop count metric.
They encode the sum of the metrics of all links of the tree. We
propose the following values for these new metric types:
o P2MP IGP metric: T=8 (suggested value, to be assigned by IANA)
o P2MP TE metric: T=9 (suggested value, to be assigned by IANA)
o P2MP hop count metric: T=10 (suggested value, to be assigned by
IANA)
3.7. Non-Support of P2MP Path Computation.
o If a PCE receives a P2MP path request and it understands the P2MP
flag in the RP object, but the PCE is not capable of P2MP
computation, the PCE MUST send a PCErr message with a PCEP-ERROR
Object and corresponding Error-Value. The request MUST then be
cancelled at the PCC. New Error-Types and Error-Values are
requested in Section 6. (IANA Considerations) of this document.
o If the PCE does not understand the P2MP flag in the RP object,
then the PCE MUST send a PCErr message with Error-value=2
(capability not supported).
3.8. Non-Support by Back-Level PCE Implementations.
If a PCE receives a P2MP request and the PCE does not understand the
P2MP flag in the RP object, and therefore the PCEP P2MP extensions,
then the PCE SHOULD reject the request.
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3.9. P2MP TE Path Reoptimization Request
A reoptimization request for a P2MP TE path is specified by the use
of the R bit within the RP object as defined in [RFC5440] and is
similar to the reoptimization request for a P2P TE path. The only
difference is that the user MUST insert the list of RROs and SRROs
after each type of END-POINTS in the PCReq message, as described in
the Request Message Format section (Section 3.4) of this document.
An example of a reoptimization request and subsequent PCReq message
is described below:
Common Header
RP with P2MP flag/R bits set
END-POINTS for leaf type 3
RRO list
OF (optional)
Figure 5: PCReq Message Example 1 for Optimization
In this example, we request reoptimization of the path to all leaves
without adding or pruning leaves. The reoptimization request would
use an END-POINT type 3. The RRO list would represent the P2MP LSP
before the optimization and the modifiable path leaves would be
indicated in the END-POINTS object.
It is also possible to specify specific leaves whose path cannot
be modified. An example of the PCReq message in this scenario would
be:
Common Header
RP with P2MP flag/R bits set
END-POINTS for leaf type 3
RRO list
END-POINTS for leaf type 4
RRO list
OF (optional)
Figure 6: PCReq Message Example 2 for Optimization
3.10. Adding and Pruning Leaves to the P2MP Tree
When adding new leaves or removing old leaves to the existing P2MP
tree, by supplying a list of existing leaves, it SHOULD be possible
to optimize the existing P2MP tree. This section explains the methods
to add new leaves or remove old leaves to the existing P2MP tree.
To add new leaves the user MUST build a P2MP request using
END-POINTS with leaf type 1.
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To remove old leaves the user must build a P2MP request using
END-POINTS with leaf type 2. If no type-2 end-points exist, then the
PCE MUST send an error type 17, value=1: The PCE is not capable to
satisfy the request due to no END-POINTS with leaf type 2.
The PCC must also provide the list of old leaves, if any, including
END-POINTS with leaf type 3, leaf type 4 or both. The error values
when the conditions are not satisfied (i.e., when there is no
END-POINTS with leaf type 3 or 4, in the presence of END-POINTS with
leaf type 1 or 2). A generic "Inconsistent END-POINT" error is also
requested if a PCC receives a request that has an inconsistent
END-POINT (i.e., if a leaf specified as type 1 already exists). The
The IANA request for all new error values is documented in Section
6.6. (PCEP Error Objects and Types) of this document.
For old leaves the user MUST provide the old path as a list of RROs
that immediately follows each END-POINTS object. This document
specifies error values when specific conditions are not satisfied.
The following examples demonstrate full and partial reoptimization
of existing P2MP LSPs:
Case 1: Adding leaves with full reoptimization of existing paths
Common Header
RP with P2MP flag/R bits set
END-POINTS for leaf type 1
RRO list
END-POINTS for leaf type 3
RRO list
OF (optional)
Case 2: Adding leaves with partial reoptimization of existing paths
Common Header
RP with P2MP flag/R bits set
END-POINTS for leaf type 1
END-POINTS for leaf type 3
RRO list
END-POINTS for leaf type 4
RRO list
OF (optional)
Case 3: Adding leaves without reoptimization of existing paths
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Common Header
RP with P2MP flag/R bits set
END-POINTS for leaf type 1
RRO list
END-POINTS for leaf type 4
RRO list
OF (optional)
Case 4: Pruning Leaves with Full Reoptimization
Common Header
RP with P2MP flag/R bits set
END-POINTS for leaf type 2
RRO list
END-POINTS for leaf type 3
RRO list
OF (optional)
Case 5: Pruning leaves with partial reoptimization of existing paths
Common Header
RP with P2MP flag/R bits set
END-POINTS for leaf type 2
RRO list
END-POINTS for leaf type 3
RRO list
END-POINTS for leaf type 4
RRO list
OF (optional)
Case 6: Pruning leaves without reoptimization of existing paths
Common Header
RP with P2MP flag/R bits set
END-POINTS for leaf type 2
RRO list
END-POINTS for leaf type 4
RRO list
OF (optional)
Case 7: Adding and pruning leaves full reoptimization of existing
paths
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Common Header
RP with P2MP flag/R bits set
END-POINTS for leaf type 1
END-POINTS for leaf type 2
RRO list
END-POINTS for leaf type 3
RRO list
OF (optional)
Case 8: Adding and pruning leaves with partial reoptimization of
existing paths
Common Header
RP with P2MP flag/R bits set
END-POINTS for leaf type 1
END-POINTS for leaf type 2
RRO list
END-POINTS for leaf type 3
RRO list
END-POINTS for leaf type 4
RRO list
OF (optional)
Case 9: Adding and pruning leaves without reoptimization of existing
paths
Common Header
RP with P2MP flag/R bits set
END-POINTS for leaf type 1
END-POINTS for leaf type 2
RRO list
END-POINTS for leaf type 4
RRO list
OF (optional)
3.11. Discovering Branch Nodes
Before computing the P2MP path, a PCE may need to be provided means
to know which nodes in the network are capable of acting as branch
LSRs. A PCE can discover such capabilities by using the mechanisms
defined in [RFC5073].
3.11.1 Branch Node Object
The PCC can specify a list of nodes that can be used as branch
nodes or a list of nodes that cannot be used as branch nodes by
using the a BRANCH NODE Capability (BNC) Object. The BNC Object has
the same format as the IRO object defined in [RFC5440] except that
it only supports IPv4 and IPv6 prefix sub-objects. Two Object-
types are also defined:
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o Branch node list: List of nodes that can be used as branch
nodes.
o Non-branch node list: List of nodes that cannot be used as branch
nodes.
The object can only be carried in a PCReq message. A Path Request
may carry at most one BRANCH NODE Object.
The Object-Class and Object-types will need to allocated by IANA. The
IANA request is documented in Section 6.5. (PCEP Objects).
3.12. Synchronization of P2MP TE Path Computation Requests
There are cases when multiple P2MP LSPs computations need to be
synchronized. For example, one P2MP LSP is the designated backup of
another P2MP LSP. In this case, path diverse for these dependent
LSPs may need to be considered during the path computation.
The synchronization can be done by using the existing SVEC
functionality defined in [RFC5440]
An example of synchronizing two P2MP LSPs, each has two leaves for
Path Computation Request Messages is illustrated as below:
Common Header
SVEC for sync of LSP1 and LSP2
OF (optional)
END-POINTS1 for P2MP
RRO1 list
END-POINTS2 for P2MP
RRO2 list
Figure 7: PCReq Message Example for Synchronization
This specification also defines two new flags to the SVEC Object Flag
Field for P2MP path dependent computation requests. The first new
flag is to allow the PCC to request that the PCE should compute a
secondary P2MP path tree with partial path diverse for specific
leaves or a specific S2L sub-path to the primary P2MP path tree.
The second flag, would allow the PCC to request that partial paths
should be link direction diverse.
The following flags are added to the SVEC object body in this
document:
o P ( Partial Path Diverse bit - 1 bit):
When set this would indicate a request for path diverse
for a specific leaf, a set of leaves or all leaves.
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o D ( Link Direction Diverse bit - 1 bit):
When set this would indicate a request that a partial path or
paths should be link direction diverse.
The IANA request is referenced in Section 6.8. of this document.
3.13. Request and Response Fragmentation
The total PCEP message-length, including the common header, is 16
bytes. In certain scenarios the P2MP computation request may not fit
into a single request or response message. For example, if a tree has
many hundreds or thousands of leaves, then the request or response
may need to be fragmented into multiple messages.
The F bit has been outlined in the Extension of the RP Object section
(Section 3.3.1) of this document. The F bit is used in the RP object
header to signal that the initial request or response was too large
to fit into a single message and will be fragmented into multiple
messages. In order to identify the single request or response, each
message will use the same request ID.
3.13.1 Request Fragmentation Procedure
If the initial request is too large to fit into a single request
message the PCC will split the request over multiple messages. Each
message sent to the PCE, except the last one, will have the F bit set
in the RP object to signify that the request has been fragmented
into multiple messages. In order to identify that a series of
request messages represents a single request, each message will
use the same request ID.
The assumption is that request messages are reliably delivered
and in sequence since PCEP relies on TCP.
3.13.2 Response Fragmentation Procedure
Once the PCE computes a path based on the initial request, a response
is sent back to the PCC. If the response is too large to fit into a
single response message the PCE will split the response over multiple
messages. Each message sent to the PCE, except the last one, will
have the F bit set in the RP object to signify that the response
has been fragmented into multiple messages. In order to identify
that a series of response messages represents a single response,
each message will use the same response ID.
Again, the assumption is that response messages are reliably
delivered and in sequence since PCEP relies on TCP.
3.13.3 Fragmentation Examples
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The following example illustrates the PCC sending a request message
with Req-ID1 to the PCE, in order to add one leaf to an existing tree
with 1200 leaves. The assumption used for this example is that one
request message can hold up to 800 leaves. In this scenario, the
original single message needs to be fragmented and sent using two
smaller messages, which have the Req-ID1 specified in the RP object,
and with the F bit set on the first message, and cleared on the
second message.
Common Header
RP1 with Req-ID1 and P2MP=1 and F-bit=1
OF (optional)
END-POINTS1 for P2MP
RRO1 list
Common Header
RP2 with Req-ID1 and P2MP=1 and F-bit=0
OF (optional)
END-POINTS1 for P2MP
RRO1 list
Figure 8: PCReq Message Fragmentation Example
To handle the scenario that the last fragmented message piece is
lost, the receiver side of the fragmented message may start a timer
once it receives the first piece of the fragmented message. When
the timer expires and it has not received the last piece of the
fragmented message, it should send an error message to the sender
to signal that it has received an incomplete message. The relevant
error message is document in Section 3.15. (P2MP PCEP Error Objects
and Types).
3.14. UNREACH-DESTINATION Object
The PCE path computation request may fail because all or a subset of
the destinations are unreachable.
In such a case, the UNREACH-DESTINATION object allows the PCE to
optionally specify the list of unreachable destinations.
This object can be present in PCRep messages. There can be up to one
such object per RP.
The following UNREACH-DESTINATION objects will be required:
UNREACH-DESTINATION Object-Class is to be assigned by IANA.
UNREACH-DESTINATION Object-Type for IPv4 is to be assigned by IANA
UNREACH-DESTINATION Object-Type for IPv6 is to be assigned by IANA.
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The format of the UNREACH-DESTINATION object body for IPv4 (Object-
Type=1) is as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination IPv4 address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ ... ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination IPv4 address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 9: UNREACH-DESTINATION Object Body for IPv4
The format of the UNREACH-DESTINATION object body for IPv6 (Object-
Type=2) is as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Destination IPv6 address (16 bytes) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ ... ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Destination IPv6 address (16 bytes) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 10: UNREACH-DESTINATION Object Body for IPv6
3.15. P2MP PCEP Error Objects and Types
To indicate an error associated with policy violation, a new error
value "P2MP Path computation not allowed" should be added to the
existing error code for policy violation (Error-Type=5) as defined
in [RFC5440]:
Error-Type=5; Error-Value=7: if a PCE receives a P2MP path
computation request which is not compliant with administrative
privileges (i.e., "The PCE policy does not support P2MP path
computation"), the PCE MUST send a PCErr message with a PCEP-ERROR
Object (Error-Type=5) and an Error-Value (Error-Value=7). The
corresponding P2MP path computation request MUST also be cancelled.
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To indicate capability errors associated with the P2MP path request,
a new Error-Type (16) and subsequent error-values are defined as
follows for inclusion in the PCEP-ERROR object:
Error-Type=16 and Error-Value=1: if a PCE receives a P2MP path
request and the PCE is not capable to satisfy the request due to
insufficient memory, the PCE MUST send a PCErr message with a PCEP
ERROR object (Error-Type=16) and an Error-Value(Error-Value=1). The
corresponding P2MP path computation request MUST also be cancelled.
Error-Type=16; Error-Value=2: if a PCE receives a P2MP path request
and the PCE is not capable of P2MP computation, the PCE MUST send a
PCErr message with a PCEP-ERROR Object (Error-Type=16) and an Error-
Value (Error-Value=2). The corresponding P2MP path computation
request MUST be also cancelled.
To indicate P2MP message fragmentation errors associated with a P2MP
path request, a new Error-Type (17) and subsequent error-values are
defined as follows for inclusion in the PCEP-ERROR object:
Error-Type=18; Error-Value=1: if a PCE has not received the last
piece of the fragmented message, it should send an error message
to the sender to signal that it has received an incomplete message
(i.e., "Fragmented request failure"), the PCE MUST send a PCErr
message with a PCEP-ERROR Object (Error-Type=18) and an Error-Value
(Error-Value=1).
3.16. PCEP NO-PATH Indicator
To communicate the reasons for not being able to find P2MP path
computation, the NO-PATH object can be used in the PCRep message.
One new bit is defined in the NO-PATH-VECTOR TLV carried in
the NO-PATH Object:
bit 24: when set, the PCE indicates that there is a reachability
problem with all or a subset of the P2MP destinations. Optionally
the PCE can specify the destination or list of destinations that are
not reachable using the new UNREACH-DESTINATION object defined in
section 3.6.
4. Manageability Considerations
[PCE-P2MP-REQ] describes various manageability requirements in
support of P2MP path computation when applying PCEP. This section
describes how manageability requirements mentioned in [PCE-P2MP-REQ]
are supported in the context of PCEP extensions specified in this
document.
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Note that [RFC5440] describes various manageability considerations in
PCEP, and most of manageability requirements mentioned in [PCE-P2MP
P2MP] are already covered there.
4.1. Control of Function and Policy
In addition to PCE configuration parameters listed in [RFC5440],
the following additional parameters might be required:
o The ability to enable to disable P2MP path computations on the
PCE.
o The PCE may be configured to enable or disable the advertizement
of its P2MP path computation capability. A PCE can advertize its
P2MP capability via the IGP discovery mechanism discussed in
Section 3.1.1. (P2MP Computation TLV in the Existing PCE Discovery
Protocol), or during the Open Message Exchange discussed in
Section 3.1.2. (Open Message Extension).
4.2. Information and Data Models
A number of MIB objects have been defined for general PCEP control
and monitoring of P2P computations in [PCEP-MIB]. [PCE-P2MP-REQ]
specifies that MIB objects will be required to support the control
and monitoring of the protocol extensions defined in this document.
A new document will be required to define MIB objects for PCEP
control and monitoring of P2MP computations.
4.3. Liveness Detection and Monitoring
There are no additional considerations beyond those expressed in
[RFC5440], since [PCE-P2MP-REQ] does not address any additional
requirements.
4.4. Verifying Correct Operation
There are no additional requirements beyond those expressed in
[RFC4657] for verifying the correct operation of the PCEP sessions.
It is expected that future MIB objects will facilitate verification
of correct operation and reporting of P2MP PCEP requests, responses
and errors.
4.5. Requirements on Other Protocols and Functional Components
The method for the PCE to obtain information about a PCE capable of
P2MP path computations via OSPF and IS-IS is discussed in Section
3.1.1 (P2MP Computation TLV in the Existing PCE Discovery Protocol)
of this document.
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The subsequent IANA requests are documented in Section 6.9 (PCE
Capability Flag) of this document.
4.6. Impact on Network Operation
It is expected that use of PCEP extensions specified in this document
will not significantly increase the level of operational traffic.
However, computing a P2MP tree may require more PCE state compared to
a P2P computation. In the event of a major network failure and
multiple recovery P2MP tree computation requests being sent to the
PCE, the load on the PCE may also be significantly increased.
5. Security Considerations
As described in [PCE-P2MP-REQ], P2MP path computation requests are
more CPU-intensive and also utilize more link bandwidth. In the
event of an unauthorized P2MP path computation request, or denial of
service attack, the subsequent PCEP requests and processing may be
disruptive to the network. Consequently, it is important that
implementations conform to the relevant security requirements of
[RFC5440] that specifically help to minimize or negate unauthorized
P2MP path computation requests and denial of service attacks. These
mechanisms include:
o Securing the PCEP session requests and responses using TCP Security
Techniques (Section 10.2. [RFC5440]).
o Authenticating the PCEP requests and responses to ensure the
message is intact and sent from an authorized node (Section 10.3.
[RFC5440]).
o Providing policy control by explicitly defining which PCCs, via IP
access-lists, are allowed to send P2MP path requests to the PCE
(Section 10.6. [RFC5440]).
PCEP operates over TCP so it is also important to secure the PCE and
PCC against TCP denial of service attacks. Section 10.7.1 of
[RFC5440] outlines a number of mechanisms for minimizing the risk of
TCP based denial of service attacks against PCEs and PCCs.
PCEP implementations SHOULD consider the additional security provided
by TCP-AO [TCP-AUTH].
6. IANA Considerations
IANA maintains a registry of PCEP parameters. A number of IANA
considerations have been highlighted in previous sections of this
document. IANA is requested to make the following allocations.
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6.1 PCEP TLV Type Indicators
As described in Section 3.1.2., the newly defined P2MP capability TLV
allows the PCE to advertize its P2MP path computation capability.
IANA is requested to make the following allocation from the "PCEP
TLV Type Indicators" sub-registry.
Value Description Reference
6 P2MP capable This.I-D
6.2 Request Parameter Bit Flags
As described in Section 3.3.1., three new RP Object Flags have
been defined. IANA is requested to make the following allocations
from the "PCEP RP Object Flag Field" Sub-Registry:
Bit Description Reference
18 Fragmentation(F-bit) This.I-D
19 P2MP (N-bit) This.I-D
20 ERO-compression (E-bit) This.I-D
6.3 Objective Functions
As described in Section 3.6.1., two new Objective Functions have been
defined. IANA is requested to make the following allocations from the
"PCEP Objective Function" sub-registry:
Code Point Name Reference
7 SPT This.I-D
8 MCT This.I-D
6.4 Metric Object Types
As described in Section 3.6.2., three new metric object T fields have
been defined. IANA is requested to make the following allocations
from the "PCEP METRIC Object T Field" sub-registry:
Value Description Reference
8 P2MP IGP metric This.I-D
9 P2MP TE metric This.I-D
10 P2MP hop count metric This.I-D
6.5 PCEP Objects
As discussed in Section 3.3.2., two new END-POINTS Object-Types are
defined. IANA is requested to make the following Object-Type
allocations from the "PCEP Objects" sub-registry:
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Object-Class Value 4
Name END-POINTS
Object-Type 3: IPv4
4: IPv6
5-15: Unassigned
Reference This.I-D
As described in Section 3.2., Section 3.11.1. and Section 3.14.,
four PCEP Object-Classes and six PCEP Object-Types have been defined.
IANA is requested to make the following allocations from the "PCEP
Objects" sub-registry:
Object-Class Value 28
Name UNREACH-DESTINATION
Object-Type 1: IPv4
2: IPv6
3-15: Unassigned
Reference This.I-D
Object-Class Value 29
Name SERO
Object-Type 1: SERO
2-15: Unassigned
Reference This.I-D
Object-Class Value 30
Name SRRO
Object-Type 1: SRRO
2-15: Unassigned
Reference This.I-D
Object-Class Value 31
Name Branch Node Capability Object
Object-Type 1: Branch node list
2: Non-branch node list
3-15: Unassigned
Reference This.I-D
6.6 PCEP Error Objects and Types
As described in Section 3.15., a number of new PCEP-ERROR Object
Error Types and Values have been defined. IANA is requested to
make the following allocations from the "PCEP PCEP-ERROR Object
Error Type and Value" sub-registry:
Error
Type Meaning Reference
5 Policy violation
Error-value=7: This.I-D
P2MP Path computation is not allowed
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16 P2MP Capability Error This.I-D
Error-Value=0: Unassigned
Error-Value=1: This.I-D
The PCE is not capable to satisfy the request
due to insufficient memory
Error-Value=2: This.I-D
The PCE is not capable of P2MP computation
17 P2MP END-POINTS Error This.I-D
Error-Value=0: Unassigned
Error-Value=1: This.I-D
The PCE is not capable to satisfy the request
due to no END-POINTS with leaf type 2
Error-Value=2: This.I-D
The PCE is not capable to satisfy the request
due to no END-POINTS with leaf type 3
Error-Value=3: This.I-D
The PCE is not capable to satisfy the request
due to no END-POINTS with leaf type 4
Error-Value=4: This.I-D
The PCE is not capable to satisfy the request
due to inconsistent END-POINTS
18 P2MP Fragmentation Error This.I-D
Error-Value=0: Unassigned
Error-Value=1: This.I-D
Fragmented request failure
6.7 PCEP NO-PATH Indicator
As discussed in Section 3.16, a new NO-PATH-VECTOR TLV Flag Field
has been defined. IANA is requested to make the following
allocation from the "PCEP NO-PATH-VECTOR TLV Flag Field"
sub-registry:
Bit Description Reference
24 P2MP Reachability Problem This.I-D
6.8 SVEC Object Flag
As discussed in Section 3.12, two new SVEC Object Flags are
defined. IANA is requested to make the following
allocation from the "PCEP SVEC Object Flag Field" sub-registry:
Zhao, King, et al. [Page 27]
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Bit Description Reference
19 Partial Path Diverse This.I-D
20 Link Direction Diverse This.I-D
6.9 PCE Capability Flag
As discussed in Section 3.1, a new OSPF Capability Flag is defined
to indicate P2MP path computation capability. IANA is requested to
make the assignment from the "OSPF Parameters Path Computation
Element (PCE) Capability Flags" registry:
Bit Description Reference
10 P2MP path computation This.I-D
7. Acknowledgements
The authors would like to thank Adrian Farrel, Young Lee, Dan
Tappan, Autumn Liu, Huaimo Chen, Eiji Okim, Nick Neate, Suresh
Babu K,Dhruv Dhody, Udayasree Palle, Gaurav Agrawal, Vishwas
Manral, Dan Romascanu, Tim Polk, Stewart Bryant, David
Harrington and Sean Turner for their valuable comments and input
on this draft.
8. References
8.1. Normative References
[RFC5440] Ayyangar, A., Farrel, A., Oki, E., Atlas, A., Dolganow,
A., Ikejiri, Y., Kumaki, K., Vasseur, J., and J. Roux,
"Path Computation Element (PCE) Communication Protocol
(PCEP)", RFC 5440, March 2009.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[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.
[RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching
(GMPLS) Signaling Resource ReserVation Protocol-Traffic
Engineering (RSVP-TE) Extensions", RFC 3473, January 2003.
[RFC4873] Berger, L., Bryskin, I., Papadimitriou, D., and A. Farrel,
"GMPLS Segment Recovery", RFC 4873, May 2007
Zhao, King, et al. [Page 28]
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[RFC4875] Aggarwal, R., Papadimitriou, D., and S. Yasukawa,
"Extensions to Resource Reservation Protocol - Traffic
Engineering (RSVP-TE) for Point-to-Multipoint TE Label
Switched Paths (LSPs)", RFC 4875, May 2007.
[RFC4970] Lindem A., et al.
"Extensions to OSPF for Advertising Optional Router
Capabilities', RFC 4970, July 2007
[RFC5073] Vasseur, JP., Le Roux, JL., "IGP Routing Protocol
Extensions for Discovery of Traffic Engineering Node
Capabilities", RFC 5073, December 2007.
[RFC5088] Le Roux, JL., Vasseur, JP., Ikejiri, Y., and R. Zhang,
"OSPF Protocol Extensions for Path Computation Element
(PCE) Discovery", RFC 5088, January 2008.
[RFC5089] Le Roux, JL., Ed., Vasseur, JP., Ed., Ikejiri, Y., and R.
Zhang, "IS-IS Protocol Extensions for Path Computation
Element (PCE) Discovery", RFC 5089, January 2008.
[RFC5511] Farrel, F., "Routing Backus-Naur Form (RBNF): A Syntax
Used to Form Encoding Rules in Various Routing Protocol
Specifications", RFC 5511, April 2009.
[RFC5541]
Roux, J., Vasseur, J., and Y. Lee, "Encoding of Objective
Functions in the Path Computation Element Communication
Protocol (PCEP)", RFC5541, December 2008.
8.2. Informative References
[RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation
Element (PCE)-Based Architecture", RFC 4655, August 2006.
[RFC5671] Yasukawa, S. and A. Farrel, "Applicability of the Path
Computation Element (PCE) to Point-to-Multipoint (P2MP)
MPLS and GMPLS Traffic Engineering (TE)" RFC 5671,
October 2009.
[PCE-P2MP-REQ]
Yasukawa, S. and A. Farrel, "PCC-PCE Communication
Requirements for Point to Multipoint Multiprotocol Label
Switching Traffic Engineering (MPLS-TE)",
draft-ietf-pce-p2mp-req-05 (work in progress),
December 2009.
[PCEP-MIB] Koushik, K., Stephan, E., Zhao, Q., and King, D.,
"PCE communication protocol(PCEP) Management
Information Base", draft-ietf-pce-pcep-mib-01 (work in
progress), March 2010.
Zhao, King, et al. [Page 29]
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[RFC4657] J. Ash, J.L Le Roux et al., " Path Computation Element
(PCE) Communication Protocol Generic Requirements", RFC
4657, September 2006.
[TCP-AUTH] Touch, J., Mankin, A., and R. Bonica, "The TCP
Authentication Option", draft-ietf-tcpm-tcp-auth-opt-11
(work in progress), March 2010.
9. Authors' Addresses
Quintin Zhao (editor)
Huawei Technology
125 Nagog Technology Park
Acton, MA 01719
US
Email: qzhao@huawei.com
Daniel King (editor)
Old Dog Consulting
UK
Email: daniel@olddog.co.uk
Fabien Verhaeghe
Thales Communication France
160 Bd Valmy 92700 Colombes
France
Email: fabien.verhaeghe@gmail.com
Tomonori Takeda
NTT Corporation
3-9-11, Midori-Cho
Musashino-Shi, Tokyo 180-8585
Japan
Email: takeda.tomonori@lab.ntt.co.jp
Zafar Ali
Cisco systems, Inc.
2000 Innovation Drive
Kanata, Ontario K2K 3E8
Canada
Email: zali@cisco.com
Julien Meuric
France Telecom
2, avenue Pierre-Marzin
22307 Lannion Cedex,
julien.meuric@orange-ftgroup.com
Zhao, King, et al. [Page 30]
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9.1 Contributors
Jean-Louis Le Roux
France Telecom
2, avenue Pierre-Marzin
22307 Lannion Cedex,
France
Email: jeanlouis.leroux@orange-ftgroup.com
Mohamad Chaitou
France
Email: mohamad.chaitou@gmail.com
Zhao, King, et al. [Page 31]
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