PCEP Extension for Tunneled Flow Specification
draft-liu-pce-pcep-tunnel-flowspec-00
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| Document | Type | Active Internet-Draft (individual) | |
|---|---|---|---|
| Author | Yao Liu | ||
| Last updated | 2025-12-18 | ||
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draft-liu-pce-pcep-tunnel-flowspec-00
PCE Y. Liu
Internet-Draft ZTE Corporation
Intended status: Standards Track 18 December 2025
Expires: 21 June 2026
PCEP Extension for Tunneled Flow Specification
draft-liu-pce-pcep-tunnel-flowspec-00
Abstract
Traffic flows may be categorized and described using "Flow
Specifications". RFC8955 defines the Flow Specification and
describes how Flow Specification components are used to describe
traffic flows. RFC8955 also defines how Flow Specifications may be
distributed in BGP to allow specific traffic flows to be associated
with routes.
RFC 9168 specifies a set of extensions to PCEP to support the
dissemination of Flow Specifications. This allows a PCE to indicate
what traffic should be placed on each path that it is aware of.
The extensions defined in this document extend the support for
tunneled traffic filtering rules.
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
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on 21 June 2026.
Copyright Notice
Copyright (c) 2025 IETF Trust and the persons identified as the
document authors. All rights reserved.
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This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://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
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Requirements Language . . . . . . . . . . . . . . . . . . 4
3. Tunneled Flow Specifications . . . . . . . . . . . . . . . . 4
3.1. Tunneled Flow Specification TLVs . . . . . . . . . . . . 5
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
4.1. PCEP TLV Type Indicators . . . . . . . . . . . . . . . . 6
4.2. Tunneled Flow Specification TLV Type Indicators . . . . . 6
5. Security Considerations . . . . . . . . . . . . . . . . . . . 7
6. Manageability Considerations . . . . . . . . . . . . . . . . 7
6.1. Control of Function and Policy . . . . . . . . . . . . . 7
6.2. Information and Data Models . . . . . . . . . . . . . . . 7
6.3. Liveness Detection and Monitoring . . . . . . . . . . . . 7
6.4. Verify Correct Operations . . . . . . . . . . . . . . . . 7
6.5. Requirements On Other Protocols . . . . . . . . . . . . . 8
6.6. Impact On Network Operations . . . . . . . . . . . . . . 8
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
7.1. Normative References . . . . . . . . . . . . . . . . . . 8
7.2. Informative References . . . . . . . . . . . . . . . . . 8
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
The description of traffic flows by the combination of multiple Flow
Specification components and their dissemination as traffic flow
specifications (Flow Specifications) is described for BGP in
[RFC8955]. In BGP, a Flow Specification is comprised of traffic
filtering rules and is associated with actions to perform on the
packets that match the Flow Specification. The BGP routers that
receive a Flow Specification can classify received packets according
to the traffic filtering rules and can direct packets based on the
associated actions. [I-D.ietf-idr-flowspec-v2] specifies version 2
of the BGP flow specification protocol that resolves some of the
issues with version 1.
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When a PCE is used to initiate tunnels (such as TE-LSPs or SR paths)
using PCEP, it is important that the head end of the tunnels
understands what traffic to place on each tunnel. The data flows
intended for a tunnel can be described using Flow Specification
components. When PCEP is in use for tunnel initiation, it makes
sense for that same protocol to be used to distribute the Flow
Specification components that describe what data is to flow on those
tunnels.
[RFC9168] specifies a set of extensions to PCEP to support the
dissemination of Flow Specification components. It includes the
creation, update, and withdrawal of Flow Specifications via PCEP. It
can be applied to tunnels initiated by the PCE or to tunnels where
control is delegated to the PCE by the PCC. Furthermore, a PCC
requesting a new path can include Flow Specifications in the request
to indicate the purpose of the tunnel allowing the PCE to factor this
into the path computation.
[I-D.ietf-pce-pcep-l2-flowspec] further extends the support for
Ethernet Layer 2 (L2) and Layer 2 Virtual Private Network (L2VPN)
traffic filtering rules in PCEP Flow Specifications.
[I-D.ietf-idr-flowspec-nvo3] defines a BGP flowspec extension to
disseminate tunneled traffic filtering rules and flow specification
components are specified for certain tunneling header fields.
This document extends the same support for PCEP by defining a new
Tunneled Flow Filter TLV to be carried within the FLOWSPEC object.
The context and the procedures for the use of Flow Specifications are
as per [RFC9168].
2. Terminology
This document uses the following terms defined in [RFC5440]: PCC,
PCE, PCEP Peer.
The following term from [RFC8955] is used frequently throughout this
document:
A Flow Specification is an n-tuple consisting of several matching
criteria that can be applied to IP traffic. A given IP packet is
said to match the defined Flow Specification if it matches all the
specified criteria.
Its usage in PCEP is further clarified in [RFC9168].
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2.1. 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. Tunneled Flow Specifications
As per [RFC9168], to carry Flow Specifications in PCEP messages, a
PCEP object called the PCEP FLOWSPEC object is defined. To describe
a traffic flow, a PCEP TLV called the Flow Filter TLV is also
defined. This document extends the support for tunneled flow
specifications by creating a new PCEP TLV called Tunneled Flow Filter
TLV and updating the processing rules.
The PCEP FLOWSPEC object carries a FlowSpec filter rule encoded in a
TLV. To describe a traffic flow based on the fields of the tunnel
encapsulation, a new Tunneled Flow Filter TLV is introduced by this
document. The PCEP FLOWSPEC object could carry no TLV or any
combination of its TLVs, i.e., Flow Filter TLV[RFC9168], L2 Flow
Filter TLV[I-D.ietf-pce-pcep-l2-flowspec] and Tunneled Flow Filter
TLV (this document), and TLV of the same type can only appear at most
once in the object.
At most one Tunneled Flow Filter TLV MAY be included in the PCEP
FLOWSPEC object. The TLV is OPTIONAL when the R (remove) bit
[RFC9168] is set in the object. At least one Flow Filter TLV or one
L2 Flow Filter TLV or one Tunneled Flow Filter TLV MUST be present
when the R bit is clear. If all the TLVs are missing when the R bit
is clear, the PCEP peer MUST respond with a PCErr message with Error-
Type 30 (FlowSpec Error) and Error-value 2 (Malformed FlowSpec).
When filtering is based on the tunneling header fields and the L3 or
L2 fields of the flow, a Flow Filter TLV or an L2 Flow Filter TLV(or
both of them) MAY be present together with the Tunneled Flow Filter
TLV.
The Tunneled TLV follows the format of all PCEP TLVs as defined in
[RFC5440]. The Type field values come from the codepoint space for
PCEP TLVs and has the value TBA1. The value field of Tunneled Flow
Filter TLV contains one or more sub-TLVs (Section 3.1), and they are
specified for certain tunneling header fields.
The rest of the procedures are same as [RFC9168].
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3.1. Tunneled Flow Specification TLVs
The Tunneled Flow Filter TLV carries one or more Tunneled Flow
Specification TLVs. The Tunneled Flow Specification TLV follows the
format of all PCEP TLVs as defined in [RFC5440]. However, the Type
values are selected from a separate IANA registry (see Section 4.2)
rather than from the common PCEP TLV registry.
Type values are chosen so that there can be commonality with Tunneled
Flow Specifications defined for use with BGP
[I-D.ietf-idr-flowspec-nvo3]. This is possible because the BGP Flow
Spec encoding uses a single octet to encode the type whereas PCEP
uses two octets. Thus the space of values for the Type field is
partitioned as shown in Figure 1.
Range |
---------------+-------------------------------------------------
0 .. 255 | Per BGP registry defined by
| [I-D.ietf-idr-flowspec-nvo3].
| Not to be allocated in this registry.
|
256 .. 65535 | New PCEP Flow Specifications allocated according
| to the registry defined in this document.
Figure 1: Tunneled Flow Specification TLV Type Ranges
[I-D.ietf-idr-flowspec-nvo3] is the reference for the registry
"Tunneled Flow Spec Component Types" and defines the allocations it
contains.
The content of the Value field in each TLV is specific to the type
and describes the parameters of the Flow Specification. The
definition of the format of many of these Value fields is inherited
from BGP specifications. Specifically, the inheritance is from
[I-D.ietf-idr-flowspec-nvo3], but may also be inherited from future
BGP specifications.
When multiple Tunneled Flow Specification TLVs are present in a
single Tunneled Flow Filter TLV, they are combined to produce a more
detailed specification of a flow. Similarly, when one of or both the
Flow Filter TLV and L2 Flow Filter TLV are present together with
Tunneled Flow Filter TLV, they are combined to produce a more
detailed specification of a flow.
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An implementation that receives a PCEP message carrying a Tunneled
Flow Specification TLV with a type value that it does not recognize
or does not support MUST respond with a PCErr message with Error-Type
30 (FlowSpec Error) and Error-value 1 (Unsupported FlowSpec) and MUST
NOT install the Flow Specification.
All Tunneled Flow Specification TLVs with Types in the range 0 to 255
have their Values interpreted as defined for use in BGP (for example,
in [I-D.ietf-idr-flowspec-nvo3]) and are set using the BGP encoding,
but without the type octet (the relevant information is in the Type
field of the TLV). The Value field is padded with trailing zeros to
achieve 4-byte alignment.
This document defines no new types.
4. IANA Considerations
IANA maintains the "Path Computation Element Protocol (PCEP) Numbers"
registry. This document requests IANA actions to allocate code
points for the protocol elements defined in this document.
4.1. PCEP TLV Type Indicators
IANA maintains a registry called "PCEP TLV Type Indicators" under the
"Path Computation Element Protocol (PCEP) Numbers" registry group.
IANA is requested to make an assignment from this registry as
follows:
Value | Meaning | Reference
--------+------------------------------+-------------
TBA1 |Tunneled FLOW FILTER TLV | this document
4.2. Tunneled Flow Specification TLV Type Indicators
IANA is requested to create a new registry called the "PCEP Tunneled
Flow Specification TLV Type Indicators" registry.
Allocations from this registry are to be made according to the
following assignment policies [RFC8126]:
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Range | Assignment policy
---------------+---------------------------------------------------
0 .. 255 | Reserved - must not be allocated.
| Usage mirrors the BGP Tunneled FlowSpec registry
| [I-D.ietf-idr-flowspec-nvo3].
|
256 .. 64506 | IETF Review
|
64507 .. 65531 | First Come First Served
|
65532 .. 65535 | Experimental
This document makes no allocations in the newly created registry.
5. Security Considerations
The security considerations in [RFC9168] apply to this document as
well.
No new security issues are introduced to the PCEP protocol by this
specification.
6. Manageability Considerations
6.1. Control of Function and Policy
[RFC9168] describe the management of multiple flowspecs as well as
control via configurations and policies. This is applicable to the
Tunneled flowspec defined in this document.
6.2. Information and Data Models
The PCEP YANG module [RFC9826] would need to be augmented to cover
tunneled flowspec.
6.3. Liveness Detection and Monitoring
Mechanisms defined in this document do not imply any new liveness
detection and monitoring requirements in addition to those already
listed in [RFC5440].
6.4. Verify Correct Operations
Mechanisms defined in this document do not imply any new operation
verification requirements in addition to those already listed in
[RFC9168].
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6.5. Requirements On Other Protocols
Mechanisms defined in this document do not imply any new requirements
on other protocols.
6.6. Impact On Network Operations
Mechanisms defined in this document do not have any new impact on
network operations in addition to those already listed in [RFC9168].
7. References
7.1. Normative References
[I-D.ietf-idr-flowspec-nvo3]
Eastlake, D. E., Weiguo, H., Zhuang, S., Li, Z., and R.
Gu, "BGP Dissemination of Flow Specification Rules for
Tunneled Traffic", Work in Progress, Internet-Draft,
draft-ietf-idr-flowspec-nvo3-23, 5 December 2025,
<https://datatracker.ietf.org/doc/html/draft-ietf-idr-
flowspec-nvo3-23>.
[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>.
[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>.
[RFC8955] Loibl, C., Hares, S., Raszuk, R., McPherson, D., and M.
Bacher, "Dissemination of Flow Specification Rules",
RFC 8955, DOI 10.17487/RFC8955, December 2020,
<https://www.rfc-editor.org/info/rfc8955>.
[RFC9168] Dhody, D., Farrel, A., and Z. Li, "Path Computation
Element Communication Protocol (PCEP) Extension for Flow
Specification", RFC 9168, DOI 10.17487/RFC9168, January
2022, <https://www.rfc-editor.org/info/rfc9168>.
7.2. Informative References
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[I-D.ietf-idr-flowspec-l2vpn]
Weiguo, H., Eastlake, D. E., Litkowski, S., and S. Zhuang,
"BGP Dissemination of L2 Flow Specification Rules", Work
in Progress, Internet-Draft, draft-ietf-idr-flowspec-
l2vpn-26, 23 September 2025,
<https://datatracker.ietf.org/doc/html/draft-ietf-idr-
flowspec-l2vpn-26>.
[I-D.ietf-idr-flowspec-v2]
Hares, S., Eastlake, D. E., Yadlapalli, C., and S.
Maduschke, "BGP Flow Specification Version 2", Work in
Progress, Internet-Draft, draft-ietf-idr-flowspec-v2-04,
28 April 2024, <https://datatracker.ietf.org/doc/html/
draft-ietf-idr-flowspec-v2-04>.
[I-D.ietf-pce-pcep-l2-flowspec]
Dhody, D., Farrel, A., and Z. Li, "PCEP Extension for
Layer 2 (L2) Flow Specification", Work in Progress,
Internet-Draft, draft-ietf-pce-pcep-l2-flowspec-09, 30
September 2025, <https://datatracker.ietf.org/doc/html/
draft-ietf-pce-pcep-l2-flowspec-09>.
[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>.
[RFC9826] Dhody, D., Ed., Beeram, V., Hardwick, J., and J. Tantsura,
"A YANG Data Model for the Path Computation Element
Communication Protocol (PCEP)", RFC 9826,
DOI 10.17487/RFC9826, September 2025,
<https://www.rfc-editor.org/info/rfc9826>.
Author's Address
Yao Liu
ZTE Corporation
China
Email: liu.yao71@zte.com.cn
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