PCE Q. Xiong
Internet-Draft ZTE Corporation
Intended status: Standards Track June 1, 2020
Expires: December 3, 2020
LSP Object Flag Extension of Stateful PCE
draft-xiong-pce-lsp-flag-02
Abstract
RFC8231 describes a set of extensions to PCEP to enable stateful
control of MPLS-TE and GMPLS Label Switched Paths(LSPs) via PCEP.
One of the extensions is the LSP object which includes a Flag field
and the length is 12 bits. However, 11 bits of the Flag field has
been assigned in RFC8231, RFC8281 and RFC8623 respectively.
This document proposes to define a new LSP-EXTENDED-FLAG TLV for LSP
object to extend the length of the flags.
Status of This Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on December 3, 2020.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions used in this document . . . . . . . . . . . . . . 3
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. Backward Compatibility . . . . . . . . . . . . . . . . . . . 4
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
5.1. LSP Object . . . . . . . . . . . . . . . . . . . . . . . 4
5.1.1. LSP-EXTENDED-FLAG TLV . . . . . . . . . . . . . . . . 4
5.1.2. LSP Extended Flags Field . . . . . . . . . . . . . . 5
5.2. PCEP-Error Object . . . . . . . . . . . . . . . . . . . . 5
6. Security Considerations . . . . . . . . . . . . . . . . . . . 5
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5
8. Normative References . . . . . . . . . . . . . . . . . . . . 6
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
[RFC5440] describes the Path Computation Element Protocol (PCEP)
which is used between a Path Computation Element (PCE) and a Path
Computation Client (PCC) (or other PCE) to enable computation of
Multi-protocol Label Switching (MPLS) for Traffic Engineering Label
Switched Path (TE LSP).
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 field indicating to a PCE that the LSP
State Synchronization is in progress.
As defined in [RFC8231], the length of the flag field is 12 bits and
the value from bit 5 to bit 11 is used for operational,
administrative, remove, synchronize and delegate respectively. The
bit value 4 is assigned in [RFC8281] for create. The bits from 1 to
3 is assigned in [RFC8623] for ERO-compression, fragmentation and
P2MP respectively. Almost all bits of the Flag field has been
assigned in RFC8231, RFC8281 and RFC8623 respectively. It is
required to extend the length of the flag field for other cases.
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This document proposes to define a new LSP-EXTENDED-FLAG TLV for LSP
object to extend the length of the flag.
2. Conventions used in this document
2.1. Terminology
The terminology is defined as [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 is defined in Section 7.3 of [RFC8231]. This document
proposes to define a new LSP-EXTENDED-FLAG TLV for LSP Object to
extend the length of the flag.
3.1. The LSP-EXTENDED-FLAG TLV
The format of the LSP-EXTENDED-FLAG TLV is as shown in the Figure 1.
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=TBD | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// LSP Extended Flags //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: LSP-EXTENDED-FLAG TLV Format
Type (16 bits): the value is TBD1 by IANA.
Length (16 bits): multiple of 4 octets.
LSP Extended Flags: this contains an array of units of 32-bit flags
numbered from the most significant as bit zero, where each bit
represents one LSP capability or state.
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3.2. Processing
The LSP Extended Flags field is an array of units of 32 flags and
being used starting from the least significant bit. Any bit being
assigned indicates a special LSP capability or state when the bit is
set to 0. No bits are defined in this document and the bits of the
LSP Extended Flags field MAY be assigned for future uses and IANA
will manage the space of the LSP Extended Flags. Unassigned bits are
reserved and SHOULD be set to zero on transmission and MUST be
ignored on receipt.
The LSP-EXTENDED-FLAG TLV MUST be included in the LSP Object when the
bits of the extended flag field need to be used. If the TLV is
missing, the PCE will generate an error with Error-type=6 (Mandatory
Object missing) and error-value TBD2 (LSP-EXTENDED-FLAG TLV missing)
and close the session.
4. Backward Compatibility
The LSP-EXTENDED-FLAG TLV defined in this document does not introduce
any interoperability issues.
A router not supporting the LSP-EXTENDED-FLAG TLV will just silently
ignore the TLV as specified in section 3.2.
The LSP-EXTENDED-FLAG TLV MUST be defined as mandatory when a router
supporting the LSP Object and needs to use the extended flag field.
5. IANA Considerations
5.1. LSP Object
5.1.1. LSP-EXTENDED-FLAG TLV
IANA has assigned a registry for TLVs carried in the LSP Object
defined in [RFC8231]. IANA is requested to make allocations for the
LSP-EXTENDED-FLAG TLV carried within LSP Object from the "PCEP TLV
Type Indicators" subregistry of the "Path Computation Element
Protocol (PCEP) Numbers" registry, as follows:
+---------+------------------------+------------------+
| Value | Description | Reference |
+---------+------------------------+------------------+
| TBD1 | LSP-EXTENDED-FLAG TLV | [This document] |
+---------+------------------------+------------------+
Table 1
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5.1.2. LSP Extended Flags Field
IANA is requested to create a new subregistry, named "LSP Extended
Flags Field", from the "Path Computation Element Protocol (PCEP)
Numbers" registry to manage the LSP Extended Flags field of the LSP-
EXTENDED-FLAG TLV. New values MUST request to be assigned by
Standards Action [RFC8126] and IANA will manage the space of the bit
flags numbering them in the usual IETF notation starting at zero and
continuing at least through 31. Each bit should be tracked with the
following qualities:
Bit number (counting from bit 0 as the most significant bit)
Capability description
Defining RFC
5.2. PCEP-Error Object
IANA is requested to register the following error types and error
values within the "PCEP-ERROR Object Error Types and Values"
subregistry of the "Path Computation Element Protocol (PCEP) Numbers"
registry:
+--------------+-------------------------------------+
| Error-Type | Meaning |
+--------------+-------------------------------------+
| 6 | Mandatory Object missing |
| | Error-value |
| | TBD2: LSP-EXTENDED-FLAG TLV missing |
+--------------+-------------------------------------+
Table 2
6. Security Considerations
For LSP Object procssing security considerations, see [RFC8231].
No additional security issues are raised in this document beyond
those that exist in the referenced documents.
7. Acknowledgements
Authors would like to thank the comments and suggestions from Dhruv
Dhody and Farrel Adrian.
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8. 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>.
[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>.
Author's Address
Quan Xiong
ZTE Corporation
No.6 Huashi Park Rd
Wuhan, Hubei 430223
China
Email: xiong.quan@zte.com.cn
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