draft-ietf-pce-association-bidir-07.txt   draft-ietf-pce-association-bidir-08.txt 
PCE Working Group R. Gandhi, Ed. PCE Working Group R. Gandhi, Ed.
Internet-Draft Cisco Systems, Inc. Internet-Draft Cisco Systems, Inc.
Intended status: Standards Track C. Barth Intended status: Standards Track C. Barth
Expires: March 13, 2021 Juniper Networks Expires: March 19, 2021 Juniper Networks
B. Wen B. Wen
Comcast Comcast
September 9, 2020 September 15, 2020
PCEP Extensions for Associated Bidirectional Label Switched Paths (LSPs) PCEP Extensions for Associated Bidirectional Label Switched Paths (LSPs)
draft-ietf-pce-association-bidir-07 draft-ietf-pce-association-bidir-08
Abstract Abstract
The Path Computation Element Communication Protocol (PCEP) provides The Path Computation Element Communication Protocol (PCEP) provides
mechanisms for Path Computation Elements (PCEs) to perform path mechanisms for Path Computation Elements (PCEs) to perform path
computations in response to Path Computation Clients (PCCs) requests. computations in response to Path Computation Clients (PCCs) requests.
The Stateful PCE extensions allow stateful control of Multiprotocol The Stateful PCE extensions allow stateful control of Multiprotocol
Label Switching (MPLS) Traffic Engineering (TE) Label Switched Paths Label Switching (MPLS) Traffic Engineering (TE) Label Switched Paths
(LSPs) using PCEP. (LSPs) using PCEP.
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material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on March 13, 2021. This Internet-Draft will expire on March 19, 2021.
Copyright Notice Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Summary of PCEP Extensions . . . . . . . . . . . . . . . 4 1.1. Summary of PCEP Extensions . . . . . . . . . . . . . . . 4
2. Conventions Used in This Document . . . . . . . . . . . . . . 4 2. Conventions Used in This Document . . . . . . . . . . . . . . 4
2.1. Key Word Definitions . . . . . . . . . . . . . . . . . . 4 2.1. Key Word Definitions . . . . . . . . . . . . . . . . . . 4
2.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5 2.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5
3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1. Single-sided Initiation . . . . . . . . . . . . . . . . . 5 3.1. Single-sided Initiation . . . . . . . . . . . . . . . . . 5
3.2. Double-sided Initiation . . . . . . . . . . . . . . . . . 6 3.2. Double-sided Initiation . . . . . . . . . . . . . . . . . 7
3.3. Co-routed Associated Bidirectional LSP . . . . . . . . . 7 3.3. Co-routed Associated Bidirectional LSP . . . . . . . . . 8
4. Protocol Extensions . . . . . . . . . . . . . . . . . . . . . 8 4. Protocol Extensions . . . . . . . . . . . . . . . . . . . . . 8
4.1. ASSOCIATION Object . . . . . . . . . . . . . . . . . . . 8 4.1. ASSOCIATION Object . . . . . . . . . . . . . . . . . . . 8
4.2. Bidirectional LSP Association Group TLV . . . . . . . . . 9 4.2. Bidirectional LSP Association Group TLV . . . . . . . . . 9
5. PCEP Procedure . . . . . . . . . . . . . . . . . . . . . . . 10 5. PCEP Procedure . . . . . . . . . . . . . . . . . . . . . . . 10
5.1. PCE Initiated LSPs . . . . . . . . . . . . . . . . . . . 10 5.1. PCE Initiated LSPs . . . . . . . . . . . . . . . . . . . 11
5.2. PCC Initiated LSPs . . . . . . . . . . . . . . . . . . . 10 5.2. PCC Initiated LSPs . . . . . . . . . . . . . . . . . . . 11
5.3. Stateless PCE . . . . . . . . . . . . . . . . . . . . . . 11 5.3. Stateless PCE . . . . . . . . . . . . . . . . . . . . . . 12
5.4. Bidirectional (B) Flag . . . . . . . . . . . . . . . . . 11 5.4. Bidirectional (B) Flag . . . . . . . . . . . . . . . . . 12
5.5. PLSP-ID Usage . . . . . . . . . . . . . . . . . . . . . . 11 5.5. PLSP-ID Usage . . . . . . . . . . . . . . . . . . . . . . 12
5.6. State Synchronization . . . . . . . . . . . . . . . . . . 12 5.6. State Synchronization . . . . . . . . . . . . . . . . . . 13
5.7. Error Handling . . . . . . . . . . . . . . . . . . . . . 12 5.7. Error Handling . . . . . . . . . . . . . . . . . . . . . 13
6. Implementation Status . . . . . . . . . . . . . . . . . . . . 13 6. Implementation Status . . . . . . . . . . . . . . . . . . . . 13
6.1. Implementation . . . . . . . . . . . . . . . . . . . . . 13 6.1. Implementation . . . . . . . . . . . . . . . . . . . . . 14
7. Security Considerations . . . . . . . . . . . . . . . . . . . 13 7. Security Considerations . . . . . . . . . . . . . . . . . . . 14
8. Manageability Considerations . . . . . . . . . . . . . . . . 14 8. Manageability Considerations . . . . . . . . . . . . . . . . 14
8.1. Control of Function and Policy . . . . . . . . . . . . . 14 8.1. Control of Function and Policy . . . . . . . . . . . . . 14
8.2. Information and Data Models . . . . . . . . . . . . . . . 14 8.2. Information and Data Models . . . . . . . . . . . . . . . 14
8.3. Liveness Detection and Monitoring . . . . . . . . . . . . 14 8.3. Liveness Detection and Monitoring . . . . . . . . . . . . 15
8.4. Verify Correct Operations . . . . . . . . . . . . . . . . 14 8.4. Verify Correct Operations . . . . . . . . . . . . . . . . 15
8.5. Requirements On Other Protocols . . . . . . . . . . . . . 14 8.5. Requirements On Other Protocols . . . . . . . . . . . . . 15
8.6. Impact On Network Operations . . . . . . . . . . . . . . 14 8.6. Impact On Network Operations . . . . . . . . . . . . . . 15
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
9.1. Association Types . . . . . . . . . . . . . . . . . . . . 14 9.1. Association Types . . . . . . . . . . . . . . . . . . . . 15
9.2. Bidirectional LSP Association Group TLV . . . . . . . . . 15 9.2. Bidirectional LSP Association Group TLV . . . . . . . . . 15
9.2.1. Flag Field in Bidirectional LSP Association Group TLV 15 9.2.1. Flag Field in Bidirectional LSP Association Group TLV 16
9.3. PCEP Errors . . . . . . . . . . . . . . . . . . . . . . . 15 9.3. PCEP Errors . . . . . . . . . . . . . . . . . . . . . . . 16
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 16 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 17
10.1. Normative References . . . . . . . . . . . . . . . . . . 16 10.1. Normative References . . . . . . . . . . . . . . . . . . 17
10.2. Informative References . . . . . . . . . . . . . . . . . 17 10.2. Informative References . . . . . . . . . . . . . . . . . 18
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 18 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 19
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 18 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19
1. Introduction 1. Introduction
[RFC5440] describes the Path Computation Element Protocol (PCEP) as a [RFC5440] describes the Path Computation Element Protocol (PCEP) as a
communication mechanism between a Path Computation Client (PCC) and a communication mechanism between a Path Computation Client (PCC) and a
Path Control Element (PCE), or between PCE and PCC, that enables Path Control Element (PCE), or between PCE and PCC, that enables
computation of Multiprotocol Label Switching (MPLS) Traffic computation of Multiprotocol Label Switching (MPLS) Traffic
Engineering (TE) Label Switched Paths (LSPs). Engineering (TE) Label Switched Paths (LSPs).
[RFC8231] specifies extensions to PCEP to enable stateful control of [RFC8231] specifies extensions to PCEP to enable stateful control of
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reverse LSP when it receives the RSVP Path delete message [RFC3209] reverse LSP when it receives the RSVP Path delete message [RFC3209]
for the forward LSP. for the forward LSP.
The originating endpoint (PCC) node may report/ delegate the forward The originating endpoint (PCC) node may report/ delegate the forward
and reverse direction LSPs to a PCE. The remote endpoint (PCC) node and reverse direction LSPs to a PCE. The remote endpoint (PCC) node
may report its forward direction LSP to a PCE. may report its forward direction LSP to a PCE.
+-----+ +-----+
| PCE | | PCE |
+-----+ +-----+
Initiates: | ^ Reports: Initiates: | \
Tunnel 1 (F) | \
(LSP1 (F, 0), LSP2 (R, 0)) | \
Association #1 v \
+-----+ +-----+
| A | | D |
+-----+ +-----+
+-----+
| PCE |
+-----+
Reports: ^ ^ Reports:
Tunnel 1 (F) | \ Tunnel 2 (F) Tunnel 1 (F) | \ Tunnel 2 (F)
(LSP1 (F, P1), LSP2 (R, P2)) | \ (LSP2 (F, P3)) (LSP1 (F, P1), LSP2 (R, P2)) | \ (LSP2 (F, P3))
Association #1 v \ Association #1 Association #1 | \ Association #1
+-----+ +-----+ +-----+ +-----+
| A | | D | | A | | D |
+-----+ +-----+ +-----+ +-----+
Figure 2: Example of PCE-Initiated Single-sided Bidirectional LSP Figure 2: Example of PCE-Initiated Single-sided Bidirectional LSP
+-----+ +-----+
| PCE | | PCE |
+-----+ +-----+
Reports/Delegates: ^ ^ Reports: Reports/Delegates: ^ ^ Reports:
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Group TLV of their ASSOCIATION Objects. Group TLV of their ASSOCIATION Objects.
The endpoint (PCC) nodes may report/ delegate the forward and reverse The endpoint (PCC) nodes may report/ delegate the forward and reverse
direction LSPs to a PCE. direction LSPs to a PCE.
+-----+ +-----+
| PCE | | PCE |
+-----+ +-----+
Initiates: | \ Initiates: Initiates: | \ Initiates:
Tunnel 1 (F) | \ Tunnel 2 (F) Tunnel 1 (F) | \ Tunnel 2 (F)
(LSP1 (F, P1)) | \ (LSP2 (F, P2)) (LSP1 (F, 0)) | \ (LSP2 (F, 0))
Association #3 v v Association #3 Association #3 v v Association #3
+-----+ +-----+ +-----+ +-----+
| A | | D | | A | | D |
+-----+ +-----+ +-----+ +-----+
Figure 4: Example of PCE-Initiated Double-sided Bidirectional LSP +-----+
| PCE |
+-----+
Reports: ^ ^ Reports:
Tunnel 1 (F) | \ Tunnel 2 (F)
(LSP1 (F, P4)) | \ (LSP2 (F, P5))
Association #3 | \ Association #3
+-----+ +-----+
| A | | D |
+-----+ +-----+
Figure 4: Example of PCE-Initiated Double-sided Bidirectional LSP
+-----+ +-----+
| PCE | | PCE |
+-----+ +-----+
Reports/Delegates: ^ ^ Reports/Delegates: Reports/Delegates: ^ ^ Reports/Delegates:
Tunnel 1 (F) | \ Tunnel 2 (F) Tunnel 1 (F) | \ Tunnel 2 (F)
(LSP1 (F, P1)) | \ (LSP2 (F, P2)) (LSP1 (F, P4)) | \ (LSP2 (F, P5))
Association #4 | \ Association #4 Association #4 | \ Association #4
+-----+ +-----+ +-----+ +-----+
| A | | D | | A | | D |
+-----+ +-----+ +-----+ +-----+
Figure 5: Example of PCC-Initiated Double-sided Bidirectional LSP Figure 5: Example of PCC-Initiated Double-sided Bidirectional LSP
As shown in Figures 4 and 5, the forward tunnel and forward LSP1 are As shown in Figures 4 and 5, the forward tunnel and forward LSP1 are
initiated on the endpoint node A and the reverse tunnel and reverse initiated on the endpoint node A and the reverse tunnel and reverse
LSP2 are initiated on the endpoint node D, either by the PCE or the LSP2 are initiated on the endpoint node D, either by the PCE or the
PCCs, respectively. PLSP-IDs used are shown in the Figures as P1 and PCCs, respectively. PLSP-IDs used are shown in the Figures as P4 and
P2. P5.
As specified in [RFC8537], for fast reroute bypass tunnel assignment, As specified in [RFC8537], for fast reroute bypass tunnel assignment,
the LSP with the higher Source Address [RFC3209] is identified as the the LSP with the higher Source Address [RFC3209] is identified as the
forward LSP of the double-sided initiated bidirectional LSP. forward LSP of the double-sided initiated bidirectional LSP.
3.3. Co-routed Associated Bidirectional LSP 3.3. Co-routed Associated Bidirectional LSP
In both single-sided and double-sided initiation cases, forward and In both single-sided and double-sided initiation cases, forward and
reverse LSPs may be co-routed as shown in Figure 6, where both reverse LSPs may be co-routed as shown in Figure 6, where both
forward and reverse LSPs of a bidirectional LSP follow the same forward and reverse LSPs of a bidirectional LSP follow the same
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5.5. PLSP-ID Usage 5.5. PLSP-ID Usage
As defined in [RFC8231], a PCEP-specific LSP Identifier (PLSP-ID) is As defined in [RFC8231], a PCEP-specific LSP Identifier (PLSP-ID) is
created by a PCC to uniquely identify an LSP and it remains the same created by a PCC to uniquely identify an LSP and it remains the same
for the lifetime of a PCEP session. for the lifetime of a PCEP session.
In case of Single-sided Bidirectional LSP Association, the reverse In case of Single-sided Bidirectional LSP Association, the reverse
LSP of a bidirectional LSP created on the originating node is LSP of a bidirectional LSP created on the originating node is
identified by the PCE using 2 different PLSP-IDs based on the PCEP identified by the PCE using 2 different PLSP-IDs based on the PCEP
session on the ingress or egress nodes for the LSP. In other words, session on the ingress or egress nodes for the LSP. In other words,
the reverse LSP on the originating node will have a PLSP-ID P1 at the the reverse LSP will have a PLSP-ID P1 at the ingress node while it
ingress node while it will have a PLSP-ID P3 at the egress node. will have a PLSP-ID P3 at the egress node. There is no change in the
This is not the case for the forward LSP of the Single-sided PLSP-ID allocation procedure for the forward LSP of the Single-sided
Bidirectional LSP on the originating node and there is no change in Bidirectional LSP on the originating node. In case of Double-sided
the PLSP-ID allocation procedure for it. In case of Double-sided
Bidirectional LSP Association, there is no change in the PLSP-ID Bidirectional LSP Association, there is no change in the PLSP-ID
allocation procedure. allocation procedure.
For an Associated Bidirectional LSP, LSP-IDENTIFIERS TLV [RFC8231] For an Associated Bidirectional LSP, LSP-IDENTIFIERS TLV [RFC8231]
MUST be included in all forward and reverse LSPs. MUST be included in all forward and reverse LSPs.
5.6. State Synchronization 5.6. State Synchronization
During state synchronization, a PCC MUST report all the existing During state synchronization, a PCC MUST report all the existing
Bidirectional LSP Association Groups to the Stateful PCE as per Bidirectional LSP Association Groups to the Stateful PCE as per
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