Internet DRAFT - draft-ietf-pce-rfc6006bis
draft-ietf-pce-rfc6006bis
PCE Working Group Q. Zhao
Internet-Draft D. Dhody, Ed.
Intended status: Standards Track R. Palleti
Obsoletes: 6006 (if approved) Huawei Technology
Expires: March 30, 2018 D. King
Old Dog Consulting
September 26, 2017
Extensions to
the Path Computation Element Communication Protocol (PCEP)
for Point-to-Multipoint Traffic Engineering Label Switched Paths
draft-ietf-pce-rfc6006bis-04
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 point-to-multipoint (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.
This document obsoletes RFC 6006.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on March 30, 2018.
Palleti. Expires March 2018 [Page 1]
draft-ietf-pce-rfc6006bis September 2017
Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
This document may contain material from IETF Documents or IETF
Contributions published or made publicly available before November
10, 2008. The person(s) controlling the copyright in some of this
material may not have granted the IETF Trust the right to allow
modifications of such material outside the IETF Standards Process.
Without obtaining an adequate license from the person(s) controlling
the copyright in such materials, this document may not be modified
outside the IETF Standards Process, and derivative works of it may
not be created outside the IETF Standards Process, except to format
it for publication as an RFC or to translate it into languages other
than English.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
1.2. Requirements Language . . . . . . . . . . . . . . . . . . 5
2. PCC-PCE Communication 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 . . . . . . . . . . . . . . . . 8
3.2. Efficient Presentation of P2MP LSPs . . . . . . . . . . . 8
3.3. P2MP Path Computation Request/Reply Message Extensions . . 9
3.3.1. The Extension of the RP Object . . . . . . . . . . . . 9
3.3.2. The New P2MP END-POINTS Object . . . . . . . . . . . . 10
3.4. Request Message Format . . . . . . . . . . . . . . . . . . 13
3.5. Reply Message Format . . . . . . . . . . . . . . . . . . . 14
3.6. P2MP Objective Functions and Metric Types . . . . . . . . 15
3.6.1. New Objective Functions . . . . . . . . . . . . . . . 15
3.6.2. New Metric Object Types . . . . . . . . . . . . . . . 16
3.7. Non-Support of P2MP Path Computation . . . . . . . . . . . 16
Palleti. Expires March 2018 [Page 2]
draft-ietf-pce-rfc6006bis September 2017
3.8. Non-Support by Back-Level PCE Implementations . . . . . . 18
3.9. P2MP TE Path Reoptimization Request . . . . . . . . . . . 18
3.10. Adding and Pruning Leaves to/from the P2MP Tree . . . . . 19
3.11. Discovering Branch Nodes . . . . . . . . . . . . . . . . 22
3.11.1. Branch Node Object . . . . . . . . . . . . . . . . . 22
3.12. Synchronization of P2MP TE Path Computation Requests . . 22
3.13. Request and Response Fragmentation . . . . . . . . . . . 23
3.13.1. Request Fragmentation Procedure . . . . . . . . . . . 24
3.13.2. Response Fragmentation Procedure . . . . . . . . . . 24
3.13.3. Fragmentation Examples . . . . . . . . . . . . . . . 24
3.14. UNREACH-DESTINATION Object . . . . . . . . . . . . . . . 25
3.15. P2MP PCEP-ERROR Objects and Types . . . . . . . . . . . . 26
3.16. PCEP NO-PATH Indicator . . . . . . . . . . . . . . . . . 27
4. Manageability Considerations . . . . . . . . . . . . . . . . . 28
4.1. Control of Function and Policy . . . . . . . . . . . . . . 28
4.2. Information and Data Models . . . . . . . . . . . . . . . 28
4.3. Liveness Detection and Monitoring . . . . . . . . . . . . 28
4.4. Verifying Correct Operation . . . . . . . . . . . . . . . 29
4.5. Requirements for Other Protocols and Functional
Components . . . . . . . . . . . . . . . . . . . . . . . . 30
4.6. Impact on Network Operation . . . . . . . . . . . . . . . 30
5. Security Considerations . . . . . . . . . . . . . . . . . . . 30
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 31
6.1. PCEP TLV Type Indicators . . . . . . . . . . . . . . . . . 31
6.2. Request Parameter Bit Flags . . . . . . . . . . . . . . . 31
6.3. Objective Functions . . . . . . . . . . . . . . . . . . . 31
6.4. Metric Object Types . . . . . . . . . . . . . . . . . . . 32
6.5. PCEP Objects . . . . . . . . . . . . . . . . . . . . . . . 32
6.6. PCEP-ERROR Objects and Types . . . . . . . . . . . . . . . 33
6.7. PCEP NO-PATH Indicator . . . . . . . . . . . . . . . . . . 34
6.8. SVEC Object Flag . . . . . . . . . . . . . . . . . . . . . 34
6.9. OSPF PCE Capability Flag . . . . . . . . . . . . . . . . . 35
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 35
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 37
8.1. Normative References . . . . . . . . . . . . . . . . . . . 37
8.2. Informative References . . . . . . . . . . . . . . . . . . 38
Appendix A. Summary of the all Changes from RFC 6006 . . . . . . . 40
Appendix A.1 RBNF Changes from RFC 6006 . . . . . . . . . . . . . 40
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 43
Palleti. Expires March 2018 [Page 3]
draft-ietf-pce-rfc6006bis September 2017
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.
[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 Label
Switching Routers (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.
This document obsoletes [RFC6006] and incorporates all outstanding
Errata:
o Erratum with IDs: 3819, 3830, 3836, 4867, 4868 and 4956.
All changes from [RFC6006] are listed in Appendix A.
1.1. Terminology
Palleti. Expires March 2018 [Page 4]
draft-ietf-pce-rfc6006bis September 2017
Terminology used in this document:
TE LSP: Traffic Engineering 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.
This document also uses the terminology defined in [RFC4655],
[RFC4875], and [RFC5440].
1.2. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. PCC-PCE Communication Requirements
This section summarizes the PCC-PCE communication requirements for
P2MP MPLS-TE LSPs described in [RFC5862]. The numbering system
corresponds to the requirement numbers used in [RFC5862].
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
Palleti. Expires March 2018 [Page 5]
draft-ietf-pce-rfc6006bis September 2017
of a P2MP LSP.
7. By default, the path returned by the PCE SHOULD use the
compressed format.
8. It MUST be possible for a single P2MP path computation request or
response to be conveyed by a sequence of messages.
9. 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.
10. P2MP path modification and P2MP path diversity MUST be supported.
11. It MUST be possible to reoptimize existing P2MP TE LSPs.
12. It MUST be possible to add and remove P2MP destinations from
existing paths.
13. It MUST be possible to specify a list of applicable branch nodes
to use when computing the P2MP path.
14. It MUST be possible for a PCC to discover P2MP path computation
capability.
15. 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 ("PCC-PCE
Communication 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 Link State Advertisement (LSA) defined in
[RFC7770] 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
Palleti. Expires March 2018 [Page 6]
draft-ietf-pce-rfc6006bis September 2017
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 assignment 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 (10) 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 3.3.2 ("The New P2MP END-POINTS
Object") to further qualify the level of support.
Palleti. Expires March 2018 [Page 7]
draft-ietf-pce-rfc6006bis September 2017
3.1.2. Open Message Extension
Based on the Capabilities Exchange requirement described in
[RFC5862], 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.
IANA has allocated value 6 from the "PCEP TLV Type Indicators" sub-
registry, as documented in Section 6.1 ("PCEP TLV Type Indicators").
The description is "P2MP capable", and 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 [RFC5862], it may be necessary to pass existing
P2MP LSP route information between the PCC and PCE in the request and
reply messages. 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 Resource Reservation Protocol Traffic
Engineering (RSVP-TE) extensions 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].
Palleti. Expires March 2018 [Page 8]
draft-ietf-pce-rfc6006bis September 2017
The Secondary Record 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 29
Name SERO
Object-Type 0: Reserved
1: SERO
2-15: Unassigned
Reference [This I-D]
Object-Class Value 30
Name SRRO
Object-Type 0: Reserved
1: SRRO
2-15: Unassigned
Reference [This I-D]
The IANA assignment is documented 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-POINTS 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 messages will need the
following additional parameters to indicate to the receiving PCE that
the request and reply messages have been fragmented across multiple
messages, that they have been requested for a P2MP path, and whether
the route is represented in the compressed or uncompressed format.
This document adds the following flags to the RP Object:
Palleti. Expires March 2018 [Page 9]
draft-ietf-pce-rfc6006bis September 2017
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 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 is
not for P2MP.
o N (P2MP bit - 1 bit):
0: This indicates that this is not a PCReq or PCRep message for
P2MP.
1: This indicates that this is a 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 is not in the compressed format. By default, the path
returned by the PCE SHOULD 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 assignment is documented 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-POINTS
objects for the P2MP path:
Palleti. Expires March 2018 [Page 10]
draft-ietf-pce-rfc6006bis September 2017
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 that 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.
Note that a P2MP path computation request can mix the different types
of leaves by including several END-POINTS objects per RP object as
shown in the PCReq Routing Backus-Naur Form (RBNF) [RFC5511] format
in Section 3.4 ("Request Message Format").
Palleti. Expires March 2018 [Page 11]
draft-ietf-pce-rfc6006bis September 2017
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
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.
Palleti. Expires March 2018 [Page 12]
draft-ietf-pce-rfc6006bis September 2017
3.4. Request Message Format
As per [RFC5440], a Path Computation Request message (also referred
to as a PCReq message) is a PCEP message sent by a PCC to a PCE to
request a path computation. A PCReq message may carry more than one
path computation request.
As per [RFC5541], the OF object MAY be carried within a PCReq
message. If an objective function is to be applied to a set of
synchronized path computation requests, the OF object MUST be carried
just after the corresponding SVEC (Synchronization VECtor) object and
MUST NOT be repeated for each elementary request.
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>
[<svec-list>]
<request-list>
where:
<svec-list>::=<SVEC>
[<OF>]
[<metric-list>]
[<svec-list>]
<request-list>::=<request>[<request-list>]
<request>::= <RP>
<end-point-rro-pair-list>
[<OF>]
[<LSPA>]
[<BANDWIDTH>]
[<metric-list>]
[<IRO>|<BNC>]
[<LOAD-BALANCING>]
where:
<end-point-rro-pair-list>::=
<END-POINTS>[<RRO-List>[<BANDWIDTH>]]
[<end-point-rro-pair-list>]
Palleti. Expires March 2018 [Page 13]
draft-ietf-pce-rfc6006bis September 2017
<RRO-List>::=(<RRO>|<SRRO>)[<RRO-List>]
<metric-list>::=<METRIC>[<metric-list>]
Figure 3. The Message Format for the Request Message
Note that 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 assignment of additional END-POINTS
Object-Types in Section 6.5 ("PCEP Objects") of this document.
3.5. Reply Message Format
The PCEP Path Computation Reply message (also referred to as a PCRep
message) is a PCEP message sent by a PCE to a requesting PCC in
response to a previously received PCReq message. PCEP supports the
bundling of multiple replies to a set of path computation requests
within a single PCRep message.
The PCRep message is encoded as follows using RBNF as defined in
[RFC5511].
Palleti. Expires March 2018 [Page 14]
draft-ietf-pce-rfc6006bis September 2017
Below is the message format for the reply message:
<PCRep Message>::= <Common Header>
<response-list>
where:
<response-list>::=<response>[<response-list>]
<response>::=<RP>
[<end-point-path-pair-list>]
[<NO-PATH>]
[<UNREACH-DESTINATION>]
[<attribute-list>]
<end-point-path-pair-list>::=
[<END-POINTS>]<path>
[<end-point-path-pair-list>]
<path> ::= (<ERO>|<SERO>) [<path>]
where:
<attribute-list>::=[<OF>]
[<LSPA>]
[<BANDWIDTH>]
[<metric-list>]
[<IRO>]
Figure 4. The Message Format for the Reply Message
The optional END-POINTS object 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 that 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
Palleti. Expires March 2018 [Page 15]
draft-ietf-pce-rfc6006bis September 2017
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
Name: Shortest Path Tree (SPT)
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
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
o P2MP TE metric: T=9
o P2MP hop count metric: T=10
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
Palleti. Expires March 2018 [Page 16]
draft-ietf-pce-rfc6006bis September 2017
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).
Palleti. Expires March 2018 [Page 17]
draft-ietf-pce-rfc6006bis September 2017
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.
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 PCC 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-bit 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 distinct leaves whose path cannot be
modified. An example of the PCReq message in this scenario would be:
Common Header
RP with P2MP flag/R-bit 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
Palleti. Expires March 2018 [Page 18]
draft-ietf-pce-rfc6006bis September 2017
3.10. Adding and Pruning Leaves to/from the P2MP Tree
When adding new leaves to or removing old leaves from the existing
P2MP tree, by supplying a list of existing leaves, it is possible to
optimize the existing P2MP tree. This section explains the methods
for adding new leaves to or removing old leaves from the existing
P2MP tree.
To add new leaves, the PCC MUST build a P2MP request using END-
POINTS with leaf type 1.
To remove old leaves, the PCC 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 of
satisfying the request due to no END-POINTS with leaf type 2.
When adding new leaves to or removing old leaves from the existing
P2MP tree, the PCC MUST also provide the list of old leaves, if any,
including END-POINTS with leaf type 3, leaf type 4, or both. New
PCEP-ERROR objects and types are necessary for reporting when certain
conditions are not satisfied (i.e., when there are no END-POINTS with
leaf type 3 or 4, or in the presence of END-POINTS with leaf type 1
or 2). A generic "Inconsistent END-POINT" error will be used if a
PCC receives a request that has an inconsistent END-POINT (i.e., if a
leaf specified as type 1 already exists). These IANA assignments are
documented in Section 6.6 ("PCEP-ERROR Objects and Types") of this
document.
For old leaves, the PCC 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-bit set
END-POINTS for leaf type 1
RRO list
END-POINTS for leaf type 3
RRO list
OF (optional)
Palleti. Expires March 2018 [Page 19]
draft-ietf-pce-rfc6006bis September 2017
Case 2: Adding leaves with partial reoptimization of existing paths
Common Header
RP with P2MP flag/R-bit 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
Common Header
RP with P2MP flag/R-bit 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 of existing paths
Common Header
RP with P2MP flag/R-bit 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-bit 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)
Palleti. Expires March 2018 [Page 20]
draft-ietf-pce-rfc6006bis September 2017
Case 6: Pruning leaves without reoptimization of existing paths
Common Header
RP with P2MP flag/R-bit 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 with full reoptimization of
existing paths
Common Header
RP with P2MP flag/R-bit 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-bit 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-bit 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)
Palleti. Expires March 2018 [Page 21]
draft-ietf-pce-rfc6006bis September 2017
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
Branch Node Capability (BNC) Object. The BNC Object has the same
format as the Include Route Object (IRO) defined in [RFC5440], except
that it only supports IPv4 and IPv6 prefix sub-objects. Two Object-
types are also defined:
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 have been allocated by IANA. The
IANA assignment 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 diversity for these dependent
LSPs may need to be considered during the path computation.
The synchronization can be done by using the existing Synchronization
VECtor (SVEC) functionality defined in [RFC5440].
Palleti. Expires March 2018 [Page 22]
draft-ietf-pce-rfc6006bis September 2017
An example of synchronizing two P2MP LSPs, each having two leaves for
Path Computation Request Messages, is illustrated below:
Common Header
SVEC for sync of LSP1 and LSP2
OF (optional)
RP for LSP1
END-POINTS1 for LSP1
RRO1 list
RP for LSP2
END-POINTS2 for LSP2
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 diversity 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 diversity for a
specific leaf, a set of leaves, or all leaves.
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 assignment 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.
Palleti. Expires March 2018 [Page 23]
draft-ietf-pce-rfc6006bis September 2017
The F-bit has been outlined in "The Extension of the RP Object"
(Section 3.3.1) of this document. The F-bit is used in the RP object
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 by 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
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.
Palleti. Expires March 2018 [Page 24]
draft-ietf-pce-rfc6006bis September 2017
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 a scenario where 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
documented 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 28.
UNREACH-DESTINATION Object-Type for IPv4 is 1.
UNREACH-DESTINATION Object-Type for IPv6 is 2.
Palleti. Expires March 2018 [Page 25]
draft-ietf-pce-rfc6006bis September 2017
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]:
Palleti. Expires March 2018 [Page 26]
draft-ietf-pce-rfc6006bis September 2017
Error-Type=5; Error-Value=7: if a PCE receives a P2MP path
computation request that 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.
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; Error-Value=1: if a PCE receives a P2MP path request
and the PCE is not capable of satisfying 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 also be cancelled.
To indicate P2MP message fragmentation errors associated with a P2MP
path request, a new Error-Type (18) 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 3.14.
Palleti. Expires March 2018 [Page 27]
draft-ietf-pce-rfc6006bis September 2017
4. Manageability Considerations
[RFC5862] describes various manageability requirements in support of
P2MP path computation when applying PCEP. This section describes how
manageability requirements mentioned in [RFC5862] are supported in
the context of PCEP extensions specified in this document.
Note that [RFC5440] describes various manageability considerations in
PCEP, and most of the manageability requirements mentioned in
[RFC5862] 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 or disable P2MP path computations on the
PCE.
o The PCE may be configured to enable or disable the advertisement
of its P2MP path computation capability. A PCE can advertise 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 [RFC7420]. [RFC5862] 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.
The PCEP YANG model "ietf-pcep" is specified in [I-D.ietf-pce-pcep-
yang]. The P2MP capability of a PCEP entity or a configured peer, can
be set using this YANG model. Also the support for P2MP path
computation can be learned using this model. The statistics are
maintained in the model "ietf-pcep-stats" as specified in [I-D.ietf-
pce-pcep-yang]. This YANG model will be required to be augmented to
also include the P2MP related statistics.
4.3. Liveness Detection and Monitoring
There are no additional considerations beyond those expressed in
[RFC5440], since [RFC5862] does not address any additional
requirements.
Palleti. Expires March 2018 [Page 28]
draft-ietf-pce-rfc6006bis September 2017
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.
Palleti. Expires March 2018 [Page 29]
draft-ietf-pce-rfc6006bis September 2017
4.5. Requirements for 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.
The subsequent IANA assignments are documented in Section 6.9 ("OSPF
PCE Capability Flag") of this document.
4.6. Impact on Network Operation
It is expected that the 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 [RFC5862], 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 a 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 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 is RECOMMENDED
using TCP security techniques such as TCP Authentication Option
(TCP-AO) [RFC5925] or using Transport Layer Security (TLS) [I-
D.ietf-pce-pceps], as per the recommendations and best current
practices in [RFC7525].
o Authenticating the PCEP requests and responses to ensure the
message is intact and sent from an authorized node using TCP-AO or
TLS is RECOMMENDED.
o Providing policy control by explicitly defining which PCCs, via IP
access-lists, are allowed to send P2MP path requests to the PCE.
PCEP operates over TCP, so it is also important to secure the PCE and
PCC against TCP denial of service attacks.
As stated in [RFC6952], PCEP implementations SHOULD support TCP-AO
Palleti. Expires March 2018 [Page 30]
draft-ietf-pce-rfc6006bis September 2017
[RFC5925] and not use TCP-MD5 because of the known vulnerabilities
and weakness.
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 made the allocations as per [RFC6006].
6.1. PCEP TLV Type Indicators
As described in Section 3.1.2., the P2MP capability TLV allows the
PCE to advertise its P2MP path computation capability.
IANA had made an allocation from the "PCEP TLV Type Indicators"
subregistry, where RFC 6006 was the reference. IANA is requested to
update the reference as follows to point to this document.
Value Description Reference
6 P2MP capable [This I-D]
6.2. Request Parameter Bit Flags
As described in Section 3.3.1, three RP Object Flags have been
defined.
IANA has made an allocations from the PCEP "RP Object Flag Field"
sub-registry, where RFC 6006 was the reference. IANA is requested to
update the reference as follows to point to this document.
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 Objective Functions have been
defined.
IANA has made an allocations from the PCEP "Objective Function" sub-
registry, where RFC 6006 was the reference.IANA is requested to
update the reference as follows to point to this document.
Palleti. Expires March 2018 [Page 31]
draft-ietf-pce-rfc6006bis September 2017
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 metric object T fields have been
defined.
IANA has made an allocations from the PCEP "METRIC Object T Field"
sub-registry, where RFC 6006 was the reference. IANA is requested to
update the reference as follows to point to this document.
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 END-POINTS Object-Types are
defined.
IANA has made the Object-Type allocations from the "PCEP Objects"
sub-registry, where RFC 6006 was the reference. IANA is requested to
update the reference as follows to point to this document.
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 has made an allocations from the "PCEP Objects" sub-registry,
where RFC 6006 was the reference. IANA is requested to update the
reference as follows to point to this document.
Also, for the following four PCEP objects, the code-point 0 for the
Object-Type field are marked "Reserved" with reference to Errata ID
4956. IANA is requested to update the reference to point to this
document.
Palleti. Expires March 2018 [Page 32]
draft-ietf-pce-rfc6006bis September 2017
Object-Class Value 28
Name UNREACH-DESTINATION
Object-Type 0: Reserved
1: IPv4
2: IPv6
3-15: Unassigned
Reference [This I-D]
Object-Class Value 29
Name SERO
Object-Type 0: Reserved
1: SERO
2-15: Unassigned
Reference [This I-D]
Object-Class Value 30
Name SRRO
Object-Type 0: Reserved
1: SRRO
2-15: Unassigned
Reference [This I-D]
Object-Class Value 31
Name Branch Node Capability Object
Object-Type 0: Reserved
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, number of PCEP-ERROR Object Error Types
and Values have been defined.
IANA has made an allocations from the PCEP "PCEP-ERROR Object Error
Types and Values" sub-registry, where RFC 6006 was the reference.
IANA is requested to update the reference as follows to point to this
document.
Error
Type Meaning Reference
5 Policy violation
Error-value=7: [This I-D]
P2MP Path computation is not allowed
Palleti. Expires March 2018 [Page 33]
draft-ietf-pce-rfc6006bis September 2017
16 P2MP Capability Error
Error-Value=0: Unassigned [This I-D]
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
Error-Value=0: Unassigned [This I-D]
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
Error-Value=0: Unassigned [This I-D]
Error-Value=1: [This I-D]
Fragmented request failure
6.7. PCEP NO-PATH Indicator
As discussed in Section 3.16, NO-PATH-VECTOR TLV Flag Field has been
defined.
IANA has made an allocation from the PCEP "NO-PATH-VECTOR TLV Flag
Field" sub-registry, where RFC 6006 was the reference. IANA is
requested to update the reference as follows to point to this
document.
Bit Description Reference
24 P2MP Reachability Problem [This I-D]
6.8. SVEC Object Flag
As discussed in Section 3.12, two SVEC Object Flags are defined.
IANA has made an allocation from the PCEP "SVEC Object Flag Field"
sub-registry, where RFC 6006 was the reference. IANA is requested to
Palleti. Expires March 2018 [Page 34]
draft-ietf-pce-rfc6006bis September 2017
update the reference as follows to point to this document.
Bit Description Reference
19 Partial Path Diverse [This I-D]
20 Link Direction Diverse [This I-D]
6.9. OSPF PCE Capability Flag
As discussed in Section 3.1.1, OSPF Capability Flag is defined to
indicate P2MP path computation capability.
IANA has made an assignment from the OSPF Parameters "Path
Computation Element (PCE) Capability Flags" registry, where RFC 6006
was the reference. IANA is requested to update the reference as
follows to point to this document.
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 the RFC 6006.
Thanks to Deborah Brungard for handling of related errata on the RFC
6006.
Authors would like to thank Jonathan Hardwick and Adrian Farrel for
providing review comments with suggested text for this document.
Thanks to Jonathan Hardwick for being the document shepherd and
provide comments and guidance.
Thanks to Ben Niven-Jenkins for RTGDIR reviews.
Thanks to Roni Even for GENART reviews.
Thanks to Fred Baker for OPSDIR review.
Thanks to Deborah Brungard for being the responsible AD and guiding
the authors.
Thanks to Mirja Kuhlewind, Alvaro Retana, Ben Campbell, Adam Roach,
Palleti. Expires March 2018 [Page 35]
draft-ietf-pce-rfc6006bis September 2017
Benoit Claise, Suresh Krishnan and Eric Rescorla for the IESG review
and comments.
Palleti. Expires March 2018 [Page 36]
draft-ietf-pce-rfc6006bis September 2017
8. References
8.1. Normative References
[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., Ed., "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.
[RFC4875] Aggarwal, R., Ed., Papadimitriou, D., Ed., and S.
Yasukawa, Ed., "Extensions to Resource Reservation
Protocol - Traffic Engineering (RSVP-TE) for Point-to-
Multipoint TE Label Switched Paths (LSPs)", RFC 4875, May
2007.
[RFC5073] Vasseur, J., Ed., and J. Le Roux, Ed., "IGP Routing
Protocol Extensions for Discovery of Traffic Engineering
Node Capabilities", RFC 5073, December 2007.
[RFC5088] Le Roux, JL., Ed., Vasseur, JP., Ed., 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, A., "Routing Backus-Naur Form (RBNF): A Syntax
Used to Form Encoding Rules in Various Routing Protocol
Specifications", RFC 5511, April 2009.
[RFC5440] Vasseur, JP., Ed., and JL. Le Roux, Ed., "Path
Computation Element (PCE) Communication Protocol (PCEP)",
RFC 5440, March 2009.
[RFC5541] Le Roux, JL., Vasseur, JP., and Y. Lee, "Encoding of
Objective Functions in the Path Computation Element
Communication Protocol (PCEP)", RFC 5541, June 2009.
Palleti. Expires March 2018 [Page 37]
draft-ietf-pce-rfc6006bis September 2017
[RFC7770] Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and
S. Shaffer, "Extensions to OSPF for Advertising Optional
Router Capabilities", RFC 7770, February 2016.
8.2. Informative References
[RFC4655] Farrel, A., Vasseur, J.-P., and J. Ash, "A Path
Computation Element (PCE)-Based Architecture", RFC 4655,
August 2006.
[RFC4657] Ash, J., Ed., and J. Le Roux, Ed., "Path Computation
Element (PCE) Communication Protocol Generic
Requirements", RFC 4657, September 2006.
[RFC5671] Yasukawa, S. and A. Farrel, Ed., "Applicability of the
Path Computation Element (PCE) to Point-to-Multipoint
(P2MP) MPLS and GMPLS Traffic Engineering (TE)",
RFC 5671, October 2009.
[RFC5862] Yasukawa, S. and A. Farrel, "Path Computation Clients
(PCC) - Path Computation Element (PCE) Requirements for
Point-to-Multipoint MPLS-TE", RFC 5862, June 2010.
[RFC5925] Touch, J., Mankin, A., and R. Bonica, "The TCP
Authentication Option", RFC 5925, DOI 10.17487/RFC5925,
June 2010.
[RFC6006] Zhao, Q., Ed., King, D., Ed., Verhaeghe, F., Takeda, T.,
Ali, Z., and J. Meuric, "Extensions to the Path
Computation Element Communication Protocol (PCEP) for
Point-to-Multipoint Traffic Engineering Label Switched
Paths", RFC 6006, September 2010.
[RFC6952] Jethanandani, M., Patel, K., and L. Zheng, "Analysis of
BGP, LDP, PCEP, and MSDP Issues According to the Keying
and Authentication for Routing Protocols (KARP) Design
Guide", RFC 6952, May 2013.
[RFC7420] Koushik, K., Stephan, E., Zhao, Q., King D., and J.
Hardwick "PCE communication protocol (PCEP) Management
Information Base (MIB) Module", RFC 7420, December 2014.
[RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre,
"Recommendations for Secure Use of Transport Layer
Security (TLS) and Datagram Transport Layer Security
(DTLS)", BCP 195, RFC 7525 May 2015.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
Palleti. Expires March 2018 [Page 38]
draft-ietf-pce-rfc6006bis September 2017
2119 Key Words", BCP 14, RFC 8174, May 2017.
[I-D.ietf-pce-pcep-yang]
Dhody, D., Hardwick, J., Beeram, V., and J. Tantsura, "A
YANG Data Model for Path Computation Element
Communications Protocol (PCEP)", draft-ietf-pce-pcep-yang
(work in progress), June 2017.
[I-D.ietf-pce-pceps]
Lopez, D., Dios, O., Wu, W., and D. Dhody, "Secure
Transport for PCEP", draft-ietf-pce-pceps (work in
progress), August 2017.
Palleti. Expires March 2018 [Page 39]
draft-ietf-pce-rfc6006bis September 2017
Appendix A. Summary of the all Changes from RFC 6006
o Updated the text to use the term "PCC" instead of "user" while
describing the encoding rules in section 3.10.
o Updated the example in figure 7 to explicitly include the RP
object.
o Corrected the description of F-bit in the RP object in section
3.13, as per the errata ID 3836.
o Corrected the description of fragmentation procedure for the
response in section 3.13.2, as per the errata ID 3819.
o Corrected the Error-Type in section 3.15 for fragmentation, as per
the errata ID 3830.
o Updated the references for OSPF Router Information Link State
Advertisement (LSA) [RFC7770] and PCEP-MIB [RFC7420].
o Add updated information and references for PCEP YANG [I-D.ietf-pce-
pcep-yang] and PCEPS [I-D.ietf-pce-pceps].
o Updated security considerations to include TCP-AO and TLS.
o Updated IANA considerations to mark code-point 0 as reserved for
the object type defined in this document, as per the errata ID 4956.
IANA references are also updated to point to this document.
Appendix A.1 RBNF Changes from RFC 6006
o Update to RBNF for Request message format:
* Update to the request message to allow for the bundling of
multiple path computation requests within a single Path
Computation Request (PCReq) message.
* Addition of <svec-list> in PCReq message. This object was missed
in [RFC6006].
* Addition of BNC object in PCReq message. This object is required
to support P2MP. It shares the same format as Include Route Object
(IRO) but it is a different object.
* Update to the <RRO-List> format, to also allow Secondary Record
Route object (SRRO). This object was missed in [RFC6006].
* Removed the BANDWIDTH Object followed by Record Route Object
Palleti. Expires March 2018 [Page 40]
draft-ietf-pce-rfc6006bis September 2017
(RRO) from <RRO-List>. As BANDWIDTH object doesn't need to follow
for each RRO in the <RRO-List>, there already exist BANDWIDTH
object follow <RRO-List> and is backward compatible with
[RFC5440].
* Update to the <end-point-rro-pair-list>, to allow optional
BANDWIDTH object only if <RRO-List> is included.
* Errata ID: 4867
o Update the RBNF for Reply message format:
* Update to the reply message to allow for bundling of multiple
path computation replies within a single Path Computation Reply
(PCRep) message.
* Addition of the UNREACH-DESTINATION in PCRep message. This
object was missed in [RFC6006].
* Errata ID: 4868
Contributors
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: tomonori.takeda@ntt.com
Zafar Ali
Cisco Systems, Inc.
2000 Innovation Drive
Kanata, Ontario K2K 3E8
Canada
EMail: zali@cisco.com
Julien Meuric
Orange
2, Avenue Pierre-Marzin
22307 Lannion Cedex
Palleti. Expires March 2018 [Page 41]
draft-ietf-pce-rfc6006bis September 2017
France
EMail: julien.meuric@orange.com
Jean-Louis Le Roux
Orange
2, Avenue Pierre-Marzin
22307 Lannion Cedex
France
EMail: jeanlouis.leroux@orange.com
Mohamad Chaitou
France
EMail: mohamad.chaitou@gmail.com
Udayasree Palle
Huawei Technologies
Divyashree Techno Park, Whitefield
Bangalore, Karnataka 560066
India
EMail: udayasreereddy@gmail.com
Palleti. Expires March 2018 [Page 42]
draft-ietf-pce-rfc6006bis September 2017
Authors' Addresses
Quintin Zhao
Huawei Technology
125 Nagog Technology Park
Acton, MA 01719
US
EMail: quintin.zhao@huawei.com
Dhruv Dhody
Huawei Technology
Divyashree Techno Park, Whitefield
Bangalore, Karnataka 560066
India
EMail: dhruv.ietf@gmail.com
Ramanjaneya Reddy Palleti
Huawei Technology
Divyashree Techno Park, Whitefield
Bangalore, Karnataka 560066
India
EMail: ramanjaneya.palleti@huawei.com
Daniel King
Old Dog Consulting
UK
EMail: daniel@olddog.co.uk
Palleti. Expires March 2018 [Page 43]
