draft-ietf-pce-association-bidir-06.txt   draft-ietf-pce-association-bidir-07.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: September 14, 2020 Juniper Networks Expires: March 13, 2021 Juniper Networks
B. Wen B. Wen
Comcast Comcast
March 13, 2020 September 9, 2020
PCEP Extensions for Associated Bidirectional Label Switched Paths (LSPs) PCEP Extensions for Associated Bidirectional Label Switched Paths (LSPs)
draft-ietf-pce-association-bidir-06 draft-ietf-pce-association-bidir-07
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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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
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Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
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 September 14, 2020. This Internet-Draft will expire on March 13, 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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message. The remote endpoint then creates the corresponding reverse message. The remote endpoint then creates the corresponding reverse
tunnel and signals the reverse LSP in response to the received RSVP tunnel and signals the reverse LSP in response to the received RSVP
Path message. Similarly, the remote endpoint node deletes the Path message. Similarly, the remote endpoint node deletes the
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: | ^ Reports:
Tunnel 1 (F) | \ Tunnel 2 (F) Tunnel 1 (F) | \ Tunnel 2 (F)
(LSP1 (F), LSP2 (R)) | \ (LSP2 (F)) (LSP1 (F, P1), LSP2 (R, P2)) | \ (LSP2 (F, P3))
Association #1 v \ Association #1 Association #1 v \ 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:
Tunnel 1 (F) | \ Tunnel 2 (F) Tunnel 1 (F) | \ Tunnel 2 (F)
(LSP1 (F), LSP2 (R)) | \ (LSP2 (F)) (LSP1 (F, P1), LSP2 (R, P2)) | \ (LSP2 (F, P3))
Association #2 | \ Association #2 Association #2 | \ Association #2
+-----+ +-----+ +-----+ +-----+
| A | | D | | A | | D |
+-----+ +-----+ +-----+ +-----+
Figure 3: Example of PCC-Initiated Single-sided Bidirectional LSP Figure 3: Example of PCC-Initiated Single-sided Bidirectional LSP
As shown in Figures 2 and 3, the forward tunnel and both forward LSP1 As shown in Figures 2 and 3, the forward tunnel and both forward LSP1
and reverse LSP2 are initiated on the originating endpoint node A, and reverse LSP2 are initiated on the originating endpoint node A,
either by the PCE or the originating PCC, respectively. The either by the PCE or the originating PCC, respectively. The
originating endpoint node A signals the properties of reverse LSP2 in originating endpoint node A signals the properties of reverse LSP2 in
the RSVP REVERSE_LSP Object in the Path message of the forward LSP1. the RSVP REVERSE_LSP Object in the Path message of the forward LSP1.
The creation of reverse tunnel and reverse LSP2 on the remote The creation of reverse tunnel and reverse LSP2 on the remote
endpoint node D is triggered by the RSVP signaled forward LSP1. endpoint node D is triggered by the RSVP signaled forward LSP1.
PLSP-IDs used are shown in the Figures as P1, P2 and P3.
As specified in [RFC8537], for fast reroute bypass tunnel assignment, As specified in [RFC8537], for fast reroute bypass tunnel assignment,
the LSP starting from the originating node is identified as the the LSP starting from the originating node is identified as the
forward LSP of the single-sided initiated bidirectional LSP. forward LSP of the single-sided initiated bidirectional LSP.
3.2. Double-sided Initiation 3.2. Double-sided Initiation
As specified in [RFC7551], in the double-sided case, the As specified in [RFC7551], in the double-sided case, the
bidirectional tunnel is provisioned on both endpoint nodes (PCCs) of bidirectional tunnel is provisioned on both endpoint nodes (PCCs) of
the tunnel. The forward and reverse LSPs of this tunnel are the tunnel. The forward and reverse LSPs of this tunnel are
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Bidirectional LSP Association" on both endpoint nodes. The forward Bidirectional LSP Association" on both endpoint nodes. The forward
and reverse LSPs are identified in the Bidirectional LSP Association and reverse LSPs are identified in the Bidirectional LSP Association
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)) | \ (LSP2 (F)) (LSP1 (F, P1)) | \ (LSP2 (F, P2))
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 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)) | \ (LSP2 (F)) (LSP1 (F, P1)) | \ (LSP2 (F, P2))
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. PCCs, respectively. PLSP-IDs used are shown in the Figures as P1 and
P2.
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 A at the the reverse LSP on the originating node will have a PLSP-ID P1 at the
ingress node while it will have a PLSP-ID B at the egress node. This ingress node while it will have a PLSP-ID P3 at the egress node.
is not the case for the forward LSP of the Single-sided Bidirectional This is not the case for the forward LSP of the Single-sided
LSP on the originating node and there is no change in the PLSP-ID Bidirectional LSP on the originating node and there is no change in
allocation procedure for it. In case of Double-sided Bidirectional the PLSP-ID allocation procedure for it. In case of Double-sided
LSP Association, there is no change in the PLSP-ID allocation Bidirectional LSP Association, there is no change in the PLSP-ID
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
[RFC8697]. After the state synchronization, the PCE MUST remove all [RFC8697]. After the state synchronization, the PCE MUST remove all
stale Bidirectional LSP Associations. stale Bidirectional LSP Associations.
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Relationships between Sets of Label Switched Paths Relationships between Sets of Label Switched Paths
(LSPs)", RFC 8697, DOI 10.17487/RFC8697, January 2020, (LSPs)", RFC 8697, DOI 10.17487/RFC8697, January 2020,
<https://www.rfc-editor.org/info/rfc8697>. <https://www.rfc-editor.org/info/rfc8697>.
10.2. Informative References 10.2. Informative References
[I-D.ietf-pce-pcep-stateful-pce-gmpls] [I-D.ietf-pce-pcep-stateful-pce-gmpls]
Lee, Y., Zheng, H., Dios, O., Lopezalvarez, V., and Z. Lee, Y., Zheng, H., Dios, O., Lopezalvarez, V., and Z.
Ali, "Path Computation Element (PCE) Protocol Extensions Ali, "Path Computation Element (PCE) Protocol Extensions
for Stateful PCE Usage in GMPLS-controlled Networks", for Stateful PCE Usage in GMPLS-controlled Networks",
draft-ietf-pce-pcep-stateful-pce-gmpls-12 (work in draft-ietf-pce-pcep-stateful-pce-gmpls-13 (work in
progress), October 2019. progress), April 2020.
[I-D.ietf-pce-pcep-yang] [I-D.ietf-pce-pcep-yang]
Dhody, D., Hardwick, J., Beeram, V., and J. Tantsura, "A Dhody, D., Hardwick, J., Beeram, V., and J. Tantsura, "A
YANG Data Model for Path Computation Element YANG Data Model for Path Computation Element
Communications Protocol (PCEP)", draft-ietf-pce-pcep- Communications Protocol (PCEP)", draft-ietf-pce-pcep-
yang-13 (work in progress), October 2019. yang-14 (work in progress), July 2020.
[I-D.ietf-pce-sr-bidir-path] [I-D.ietf-pce-sr-bidir-path]
Li, C., Chen, M., Cheng, W., Gandhi, R., and Q. Xiong, Li, C., Chen, M., Cheng, W., Gandhi, R., and Q. Xiong,
"PCEP Extensions for Associated Bidirectional Segment "PCEP Extensions for Associated Bidirectional Segment
Routing (SR) Paths", draft-ietf-pce-sr-bidir-path-01 (work Routing (SR) Paths", draft-ietf-pce-sr-bidir-path-02 (work
in progress), February 2020. in progress), March 2020.
[RFC5654] Niven-Jenkins, B., Ed., Brungard, D., Ed., Betts, M., Ed., [RFC5654] Niven-Jenkins, B., Ed., Brungard, D., Ed., Betts, M., Ed.,
Sprecher, N., and S. Ueno, "Requirements of an MPLS Sprecher, N., and S. Ueno, "Requirements of an MPLS
Transport Profile", RFC 5654, DOI 10.17487/RFC5654, Transport Profile", RFC 5654, DOI 10.17487/RFC5654,
September 2009, <https://www.rfc-editor.org/info/rfc5654>. September 2009, <https://www.rfc-editor.org/info/rfc5654>.
[RFC7420] Koushik, A., Stephan, E., Zhao, Q., King, D., and J. [RFC7420] Koushik, A., Stephan, E., Zhao, Q., King, D., and J.
Hardwick, "Path Computation Element Communication Protocol Hardwick, "Path Computation Element Communication Protocol
(PCEP) Management Information Base (MIB) Module", (PCEP) Management Information Base (MIB) Module",
RFC 7420, DOI 10.17487/RFC7420, December 2014, RFC 7420, DOI 10.17487/RFC7420, December 2014,
 End of changes. 14 change blocks. 
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