PCE
Internet Engineering Task Force (IETF) Q. Xiong
Internet-Draft
Request for Comments: 9357 ZTE Corporation
Intended status:
Category: Standards Track 23 October 2022
Expires: 26 April January 2023
ISSN: 2070-1721
Label Switched Path (LSP) Object Flag Extension for Stateful PCE
draft-ietf-pce-lsp-extended-flags-09
Abstract
RFC 8231 describes a set of extensions to the Path Computation
Element Communication Protocol (PCEP) to enable stateful control of
MPLS-TE and GMPLS Label Switched Paths (LSPs) via PCEP. One of the
extensions is the LSP object object, which includes a Flag field with a
length of 12 bits. However, all bits of the Flag field have already
been assigned in RFC 8231, RFC 8281, RFC 8623 and I-D.ietf-pce-
binding-label-sid.
[Note to RFC Editor - Replace I-D.ietf-pce-binding-label-sid to RFC
XXXX, once the RFC number is assigned.] assigned.
This document proposes to define defines a new LSP-EXTENDED-FLAG TLV for the LSP object
for an extended flag Flag field.
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 an Internet Standards Track document.
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(IETF). Note that other groups may also distribute
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Internet-Drafts are draft documents valid the IETF community. It has
received public review and has been approved for a maximum publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
Information about the current status of six months this document, any errata,
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on 26 April 2023.
https://www.rfc-editor.org/info/rfc9357.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions used Used in this document . . . . . . . . . . . . . . 3 Document
2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2.2. Requirements Language . . . . . . . . . . . . . . . . . . 3
3. PCEP Extension . . . . . . . . . . . . . . . . . . . . . . . 3
3.1. The LSP-EXTENDED-FLAG TLV . . . . . . . . . . . . . . . . 3
3.2. Processing . . . . . . . . . . . . . . . . . . . . . . . 4
4. Advice for Specification of New Flags . . . . . . . . . . . . 5
5. Backward Compatibility . . . . . . . . . . . . . . . . . . . 5
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
6.1. LSP Object . . . . . . . . . . . . . . . . . . . . . . . 5
6.1.1. PCEP TLV Type Indicators . . . . . . . . . . . . . . 5
6.1.2. LSP Extended Flags Field . . . . . . . . . . . . . . 6
7. Implementation Status . . . . . . . . . . . . . . . . . . . . 6
8. Management Considerations . . . . . . . . . . . . . . . . . . 7
9.
8. Security Considerations . . . . . . . . . . . . . . . . . . . 7
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 7
12.
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
12.1.
9.1. Normative References . . . . . . . . . . . . . . . . . . 7
12.2.
9.2. Informative References . . . . . . . . . . . . . . . . . 8
Appendix A. WG Working Group Discussion . . . . . . . . . . . . . . . . . . . 9
Acknowledgements
Contributors
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction
[RFC5440] describes the Path Computation Element (PCE) Communication
Protocol (PCEP) (PCEP), which is used between a PCE and a Path Computation
Client (PCC) (or other PCE) to enable computation of Multi-protocol
Label Switching for Traffic Engineering (MPLS-TE) Label Switched Path
(LSP).
Paths (LSPs).
PCEP Extensions for the Stateful PCE Model [RFC8231] describes a set
of extensions to PCEP to enable active control of MPLS-TE and
Generalized MPLS (GMPLS) tunnels. One of the extensions is the LSP
object, which contains a flag Flag field; bits in the flag Flag field are used
to indicate delegation, synchronization, removal, etc.
As defined in [RFC8231], the length of the flag Flag field is 12 bits bits, and
the values from bit 5 to bit 11 are used for operational,
administrative, remove, synchronize and delegate bits respectively.
The bit value 4 is assigned in [RFC8281] to identify the PCE-
Initiated LSPs. The bits from 1 to 3 are assigned in [RFC8623] for
Explicit Route Object (ERO)-compression, fragmentation and Point-to-
Multipoint (P2MP) respectively. The bit 0 is assigned in
[I-D.ietf-pce-binding-label-sid] to PCE-allocation. All bits
all of the
Flag field bits have already been assigned already. defined as shown in Table 1. This
document extends the
flag Flag field of the LSP Object object for other use.
This document proposes to define use by
defining a new LSP-EXTENDED-FLAG TLV for an extended flag Flag field in
the LSP object. object (see Section 3.1).
+=====+======================+==================+
| Bit | Description | Reference |
+=====+======================+==================+
| 0 | PCE-allocation | [BIND-LABEL-SID] |
+-----+----------------------+------------------+
| 1 | ERO-compression | [RFC8623] |
+-----+----------------------+------------------+
| 2 | Fragmentation | [RFC8623] |
+-----+----------------------+------------------+
| 3 | P2MP | [RFC8623] |
+-----+----------------------+------------------+
| 4 | Create | [RFC8281] |
+-----+----------------------+------------------+
| 5-7 | Operational (3 bits) | [RFC8281] |
+-----+----------------------+------------------+
| 8 | Administrative | [RFC8281] |
+-----+----------------------+------------------+
| 9 | Remove | [RFC8281] |
+-----+----------------------+------------------+
| 10 | SYNC | [RFC8281] |
+-----+----------------------+------------------+
| 11 | Delegate | [RFC8281] |
+-----+----------------------+------------------+
Table 1: LSP Object Flag Field
2. Conventions used Used in this document Document
2.1. Terminology
The terminology is defined as in [RFC5440] and [RFC8231].
2.2. 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.
3. PCEP Extension
The LSP Object object is defined in Section 7.3 of [RFC8231]. This document
proposes to define
defines a new LSP-EXTENDED-FLAG TLV for an extended flag Flag field in the
LSP object.
3.1. The LSP-EXTENDED-FLAG TLV
The format of the LSP-EXTENDED-FLAG TLV shown in Figure 1 follows the
format of all PCEP TLVs TLVs, as defined in [RFC5440] and is shown in Figure 1. [RFC5440].
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=TBD1 Type=64 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// LSP Extended Flags //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Figure 1: LSP-EXTENDED-FLAG TLV Format
Type (16 bits): TBD1. 64
Length (16 bits): This indicates the length of the value portion in
bytes. It MUST be in multiples of 4 and greater than 0.
LSP Extended Flags: this This contains an array of units of 32-bit flags
numbered from the most significant as bit zero, where each bit
represents one LSP flag (for operation, feature, or state). The
LSP Extended Flags field SHOULD use the minimal amount of space
needed to encode the flag bits. Currently, no bits are assigned.
Unassigned bits MUST be set to zero on transmission and MUST be
ignored on receipt.
As an example of usage of the LSP-EXTENDED-FLAG TLV, the E-flag is
requested for entropy label configuration configuration, as proposed in
[I-D.peng-pce-entropy-label-position].
[PCEP-ENTROPY-LABEL].
3.2. Processing
The LSP Extended Flags field is an array of units of 32 flags, to be flags that
are allocated starting from the most significant bit. The bits of
the LSP Extended Flags field will be assigned by future documents.
This document does not define any flags. Flags that an
implementation is not supporting MUST be set to zero on transmission.
Implementations that do not understand any particular flag MUST
ignore the flag.
Note that PCEP peers MUST handle varying lengths of the LSP-EXTENDED-
FLAG TLV.
If a PCEP speaker receives the LSP-EXTENDED-FLAG TLV of a length more
than it currently supports or understands, it MUST ignore the bits
beyond that length.
If a PCEP speaker receives the LSP-EXTENDED-FLAG TLV of a length less
than the one supported by the implementation, it MUST treat act as if the
bits beyond the length to be unset. were not set.
4. Advice for Specification of New Flags
Following the model provided in [RFC8786] Section 3.1, 3.1 of [RFC8786], we provide
the following advice for new specifications that define additional
flags. Each such specification is expected to describe the
interaction between these new flags and any existing flags. In
particular, new specifications are expected to explain how to handle
the cases when both new and pre-existing preexisting flags are set. They are also
expected to discuss any security implications of the additional flags
(if any) and their interactions with existing flags.
5. Backward Compatibility
The LSP-EXTENDED-FLAG TLV defined in this document does not introduce
any backward compatibility issues. An implementation that does not
understand or support the LSP-EXTENDED-FLAG TLV MUST ignore the TLV TLV,
as per [RFC5440]. It is expected that future Future documents that define bits in the LSP-EXTENDED-FLAG LSP-
EXTENDED-FLAG TLV will are expected to also define the error case handling
required for missing cases in which the LSP-EXTENDED-FLAG TLV if is missing when
it MUST be present.
Further, any additional bits in the LSP-EXTENDED-FLAG TLV that are
not understood by an implementation MUST be ignored. It is expected
that future documents that define bits in the LSP-EXTENDED-FLAG TLV
will take take that into consideration.
6. IANA Considerations
6.1. LSP Object
6.1.1. PCEP TLV Type Indicators
IANA is requested to allocate has allocated the following TLV Type Indicator value within the
"PCEP TLV Type Indicators" subregistry registry of the "Path Computation Element
Protocol (PCEP) Numbers" registry:
+=======+===================+=================+
+=======+===================+===========+
| Value | Description | Reference |
+=======+===================+=================+
+=======+===================+===========+
| TBD1 64 | LSP-EXTENDED-FLAG | [This document] RFC 9357 |
+-------+-------------------+-----------------+
+-------+-------------------+-----------+
Table 1 2
6.1.2. LSP Extended Flags Field
IANA is requested to create a new subregistry called "LSP-EXTENDED-
FLAG has created the "LSP-EXTENDED-FLAG TLV Flag Field", Field" registry
within the "Path Computation Element Protocol (PCEP) Numbers"
registry to manage the LSP Extended Flags field of the LSP-EXTENDED-FLAG LSP-EXTENDED-
FLAG TLV. New values are assigned by Standards Action [RFC8126].
Each bit should be tracked with the following qualities:
* Bit number (counting from bit 0 as the most significant bit)
* Capability description Description
* Defining RFC Reference
No values are currently defined. Bits 0-31 should are initially be marked as
"Unassigned". Bits with a higher ordinal than 31 will be added to
the registry in future documents if necessary.
7. Implementation Status
[NOTE TO RFC EDITOR : This whole section and the reference to
[RFC7942] is to be removed before publication as an RFC]
This section records the status of known implementations of the
protocol defined by this specification at the time of posting of this
Internet-Draft, and is based on a proposal described in [RFC7942].
The description of implementations in this section is intended to
assist the IETF in its decision processes in progressing drafts to
RFCs. Please note that the listing of any individual implementation
here does not imply endorsement by the IETF. Furthermore, no effort
has been spent to verify the information presented here that was
supplied by IETF contributors. This is not intended as, and must not
be construed to be, a catalog of available implementations or their
features. Readers are advised to note that other implementations may
exist.
According to [RFC7942], "this will allow reviewers and working groups
to assign due consideration to documents that have the benefit of
running code, which may serve as evidence of valuable experimentation
and feedback that have made the implemented protocols more mature.
It is up to the individual working groups to use this information as
they see fit".
At the time of posting this version of this document, there are no
known implementations of this TLV. It is believed that this would be
implemented alongside the documents that allocate flags in the TLV.
8. Management Considerations
Implementations receiving set LSP Extended Flags that they do not
recognize MAY log this. That could be helpful for diagnosing
backward compatibility issues with future features that utilize those
flags.
9.
8. Security Considerations
[RFC8231] sets out security considerations for PCEP when used for
communication with a stateful PCE. This document does not change
those considerations. For LSP Object object processing, see [RFC8231].
The flags for the LSP object and their associated security
considerations are specified in [RFC8231], [RFC8281], [RFC8623], and
[I-D.ietf-pce-binding-label-sid].
[BIND-LABEL-SID].
This document provides for the future addition of flags in the LSP
Object.
object. Any future document that specifies new flags must also
discuss any associated security implications. No additional security
issues are raised in this document beyond those that exist in the
referenced documents. Note that the [RFC8231] recommends that the
stateful PCEP extension are be authenticated and encrypted using
Transport Layer Security (TLS) [RFC8253], [RFC8253] [PCEPS-TLS1.3], as per the
recommendations and best current practices in [RFC7525]. [RFC9325]. Assuming
that the recommendation is followed, then the flags will be protected
by TLS.
10. Acknowledgements
The authors would like to thank Loa Andersson, Adrian Farrel, Aijun
Wang, and Gyan Mishra for their review, suggestions and comments to
this document.
11. Contributors
The following people have substantially contributed to this document:
Dhruv Dhody
Huawei Technologies
EMail: dhruv.ietf@gmail.com
Greg Mirsky
Ericsson
Email: gregimirsky@gmail.com
12.
9. References
12.1.
9.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
Element (PCE) Communication Protocol (PCEP)", RFC 5440,
DOI 10.17487/RFC5440, March 2009,
<https://www.rfc-editor.org/info/rfc5440>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8231] Crabbe, E., Minei, I., Medved, J., and R. Varga, "Path
Computation Element Communication Protocol (PCEP)
Extensions for Stateful PCE", RFC 8231,
DOI 10.17487/RFC8231, September 2017,
<https://www.rfc-editor.org/info/rfc8231>.
12.2.
9.2. Informative References
[I-D.ietf-pce-binding-label-sid]
[BIND-LABEL-SID]
Sivabalan, S., Filsfils, C., Tantsura, J., Previdi, S.,
and C. L. (editor), Li, Ed., "Carrying Binding Label/Segment Identifier
(SID) in PCE-based Networks.", Work in Progress, Internet-Draft, draft-ietf-pce-binding-label-
sid-15, Internet-
Draft, draft-ietf-pce-binding-label-sid-15, 20 March 2022, <https://www.ietf.org/archive/id/
draft-ietf-pce-binding-label-sid-15.txt>.
[I-D.peng-pce-entropy-label-position]
<https://datatracker.ietf.org/doc/html/draft-ietf-pce-
binding-label-sid-15>.
[PCEP-ENTROPY-LABEL]
Xiong, Q., Peng, S., and F. Qin, "PCEP Extension for SR-
MPLS Entropy Label Position", Work in Progress, Internet-
Draft, draft-peng-pce-entropy-label-position-08, 29 August
2022, <https://www.ietf.org/archive/id/draft-peng-pce-
entropy-label-position-08.txt>. <https://datatracker.ietf.org/doc/html/draft-peng-
pce-entropy-label-position-08>.
[PCEPS-TLS1.3]
Dhody, D., Turner, S., and R. Housley, "PCEPS with TLS
1.3", Work in Progress, Internet-Draft, draft-dhody-pce-
pceps-tls13-01, 20 October 2022,
<https://datatracker.ietf.org/doc/html/draft-dhody-pce-
pceps-tls13-01>.
[RFC5088] Le Roux, JL., Ed., Vasseur, JP., Ed., Ikejiri, Y., and R.
Zhang, "OSPF Protocol Extensions for Path Computation
Element (PCE) Discovery", RFC 5088, DOI 10.17487/RFC5088,
January 2008, <https://www.rfc-editor.org/info/rfc5088>.
[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, DOI 10.17487/RFC5089,
January 2008, <https://www.rfc-editor.org/info/rfc5089>.
[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, DOI 10.17487/RFC7525, May
2015, <https://www.rfc-editor.org/info/rfc7525>.
[RFC7942] Sheffer, Y. and A. Farrel, "Improving Awareness of Running
Code: The Implementation Status Section", BCP 205,
RFC 7942, DOI 10.17487/RFC7942, July 2016,
<https://www.rfc-editor.org/info/rfc7942>.
[RFC8253] Lopez, D., Gonzalez de Dios, O., Wu, Q., and D. Dhody,
"PCEPS: Usage of TLS to Provide a Secure Transport for the
Path Computation Element Communication Protocol (PCEP)",
RFC 8253, DOI 10.17487/RFC8253, October 2017,
<https://www.rfc-editor.org/info/rfc8253>.
[RFC8281] Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "Path
Computation Element Communication Protocol (PCEP)
Extensions for PCE-Initiated LSP Setup in a Stateful PCE
Model", RFC 8281, DOI 10.17487/RFC8281, December 2017,
<https://www.rfc-editor.org/info/rfc8281>.
[RFC8623] Palle, U., Dhody, D., Tanaka, Y., and V. Beeram, "Stateful
Path Computation Element (PCE) Protocol Extensions for
Usage with Point-to-Multipoint TE Label Switched Paths
(LSPs)", RFC 8623, DOI 10.17487/RFC8623, June 2019,
<https://www.rfc-editor.org/info/rfc8623>.
[RFC8786] Farrel, A., "Updated Rules for Processing Stateful PCE
Request Parameters Flags", RFC 8786, DOI 10.17487/RFC8786,
May 2020, <https://www.rfc-editor.org/info/rfc8786>.
[RFC9325] Sheffer, Y., Saint-Andre, P., and T. Fossati,
"Recommendations for Secure Use of Transport Layer
Security (TLS) and Datagram Transport Layer Security
(DTLS)", BCP 195, RFC 9325, DOI 10.17487/RFC9325, November
2022, <https://www.rfc-editor.org/info/rfc9325>.
Appendix A. WG Working Group Discussion
The WG working group discussed the idea of a fixed length (with 32 bits)
for LSP-
EXTENDED-FLAG the LSP-EXTENDED-FLAG TLV. Though 32 bits would be sufficient
for quite a while, the use of variable length with a multiple of 32-bits 32
bits allows for future extensibility where we would never run out of
flags and there would not be a need to define yet another TLV in the
future. Further, note that [RFC5088] and [RFC5089] use the same
approach for the PCE-CAP-FLAGS Sub-TLV sub-TLV and are found to be useful.
Acknowledgements
The authors would like to thank Loa Andersson, Adrian Farrel, Aijun
Wang, and Gyan Mishra for their reviews, suggestions, and comments
for this document.
Contributors
The following people have substantially contributed to this document:
Dhruv Dhody
Huawei Technologies
Email: dhruv.ietf@gmail.com
Greg Mirsky
Ericsson
Email: gregimirsky@gmail.com
Author's Address
Quan Xiong
ZTE Corporation
No.6 Huashi Park Rd
Wuhan
Hubei, 430223
China
Email: xiong.quan@zte.com.cn