draft-ietf-pce-lsp-control-request-00.txt   draft-ietf-pce-lsp-control-request-01.txt 
PCE Working Group A. Raghuram PCE Working Group A. Raghuram
Internet-Draft A. Goddard Internet-Draft A. Goddard
Intended status: Standards Track C. Yadlapalli Intended status: Standards Track C. Yadlapalli
Expires: August 13, 2018 AT&T Expires: December 20, 2018 AT&T
J. Karthik J. Karthik
S. Sivabalan S. Sivabalan
J. Parker J. Parker
Cisco Systems, Inc. Cisco Systems, Inc.
D. Dhody D. Dhody
Huawei Technologies Huawei Technologies
February 9, 2018 June 18, 2018
Ability for a stateful PCE to request and obtain control of a LSP Ability for a stateful PCE to request and obtain control of a LSP
draft-ietf-pce-lsp-control-request-00 draft-ietf-pce-lsp-control-request-01
Abstract Abstract
The stateful Path Computation Element (PCE) communication Protocol The stateful Path Computation Element (PCE) communication Protocol
(PCEP) extensions provide stateful control of Multiprotocol Label (PCEP) extensions provide stateful control of Multiprotocol Label
Switching (MPLS) Traffic Engineering Label Switched Paths (TE LSP) Switching (MPLS) Traffic Engineering Label Switched Paths (TE LSP)
via PCEP, for a model where a Path Computation Client (PCC) delegates via PCEP, for a model where a Path Computation Client (PCC) delegates
control over one or more locally configured LSPs to a stateful PCE. control over one or more locally configured LSPs to a stateful PCE.
There are use-cases in which a stateful PCE may wish to request and There are use-cases in which a stateful PCE may wish to request and
obtain control of one or more LSPs from a PCC. This document obtain control of one or more LSPs from a PCC. This document
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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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 August 13, 2018. This Internet-Draft will expire on December 20, 2018.
Copyright Notice Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. LSP Control Request Flag . . . . . . . . . . . . . . . . . . 4 3. LSP Control Request Flag . . . . . . . . . . . . . . . . . . 4
4. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . 5 5. Security Considerations . . . . . . . . . . . . . . . . . . . 5
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
6.1. SRP Object Flags . . . . . . . . . . . . . . . . . . . . 5 6.1. SRP Object Flags . . . . . . . . . . . . . . . . . . . . 6
7. Manageability Considerations . . . . . . . . . . . . . . . . 6 7. Manageability Considerations . . . . . . . . . . . . . . . . 6
7.1. Control of Function and Policy . . . . . . . . . . . . . 6 7.1. Control of Function and Policy . . . . . . . . . . . . . 6
7.2. Information and Data Models . . . . . . . . . . . . . . . 6 7.2. Information and Data Models . . . . . . . . . . . . . . . 6
7.3. Liveness Detection and Monitoring . . . . . . . . . . . . 6 7.3. Liveness Detection and Monitoring . . . . . . . . . . . . 6
7.4. Verify Correct Operations . . . . . . . . . . . . . . . . 6 7.4. Verify Correct Operations . . . . . . . . . . . . . . . . 6
7.5. Requirements On Other Protocols . . . . . . . . . . . . . 6 7.5. Requirements On Other Protocols . . . . . . . . . . . . . 6
7.6. Impact On Network Operations . . . . . . . . . . . . . . 6 7.6. Impact On Network Operations . . . . . . . . . . . . . . 7
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
9.1. Normative References . . . . . . . . . . . . . . . . . . 7 9.1. Normative References . . . . . . . . . . . . . . . . . . 7
9.2. Informative References . . . . . . . . . . . . . . . . . 7 9.2. Informative References . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction 1. Introduction
Stateful PCEP extensions [RFC8231] specifies a set of extensions to Stateful PCEP extensions [RFC8231] specifies a set of extensions to
PCEP [RFC5440] to enable stateful control of TE LSPs between and PCEP [RFC5440] to enable stateful control of TE LSPs between and
across PCEP sessions in compliance with [RFC4657]. It includes across PCEP sessions in compliance with [RFC4657]. It includes
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load. The PCEs could use proprietary algorithm to decide which LSPs load. The PCEs could use proprietary algorithm to decide which LSPs
to be assigned to the new vPCE. Thus having a mechanism for the PCE to be assigned to the new vPCE. Thus having a mechanism for the PCE
to request control of some LSPs is needed. to request control of some LSPs is needed.
In some deployments, the operator would like to use stateful PCE for In some deployments, the operator would like to use stateful PCE for
global optimization algorithms but would still like to keep the global optimization algorithms but would still like to keep the
control of the LSP at the PCC. In such cases, a stateful PCE could control of the LSP at the PCC. In such cases, a stateful PCE could
request to take control during the global optimization and return the request to take control during the global optimization and return the
delegation once done. delegation once done.
Note that [RFC8231] specify a mechanism for a PCC to delegate an
orphaned LSP to another PCE. The mechanism defined in this document
can be used in conjunction to [RFC8231]. Ultimately, it is the PCC
that decides which PCE to delegate the orphaned LSP.
This specification provides a simple extension, by using this a PCE This specification provides a simple extension, by using this a PCE
can request control of one or more LSPs from any PCC over the can request control of one or more LSPs from any PCC over the
stateful PCEP channel. The procedures for granting and relinquishing stateful PCEP session. The procedures for granting and relinquishing
control of the LSPs are specified in accordance with the control of the LSPs are specified in accordance with the
specification [RFC8231]. specification [RFC8231].
2. Terminology 2. Terminology
The following terminologies are used in this document: The following terminologies are used in this document:
PCC: Path Computation Client. PCC: Path Computation Client.
PCE: Path Computation Element PCE: Path Computation Element
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PCRpt: Path Computation State Report message. PCRpt: Path Computation State Report message.
PCUpd: Path Computation Update Request message. PCUpd: Path Computation Update Request message.
PLSP-ID: A PCEP-specific identifier for the LSP. PLSP-ID: A PCEP-specific identifier for the LSP.
3. LSP Control Request Flag 3. LSP Control Request Flag
The Stateful PCE Request Parameters (SRP) object is defined in The Stateful PCE Request Parameters (SRP) object is defined in
[RFC8231], it includes a Flags field. [RFC8231], it includes a Flags field. [RFC8281] defines a R (LSP-
[I-D.ietf-pce-pce-initiated-lsp] defines a R (LSP-REMOVE) flag. REMOVE) flag.
A new flag, the "LSP Control Request Flag" (C), is introduced in the A new flag, the "LSP Control Request Flag" (C), is introduced in the
SRP object. On a PCUpd message, a PCE sets the C Flag to 1 to SRP object. On a PCUpd message, a PCE sets the C Flag to 1 to
indicate that, it wishes to gain control of LSP(s). The LSP is indicate that, it wishes to gain control of LSP(s). The LSP is
identified by the LSP object. A PLSP-ID of value other than 0 and identified by the LSP object. A PLSP-ID of value other than 0 and
0xFFFFF is used to identify the LSP for which the PCE requests 0xFFFFF is used to identify the LSP for which the PCE requests
control. The PLSP-ID value of 0 indicates that the PCE is requesting control. The PLSP-ID value of 0 indicates that the PCE is requesting
control of all LSPs originating from the PCC that it wishes to control of all LSPs originating from the PCC that it wishes to
delegate. The flag has no meaning in the PCRpt and PCInitiate delegate. The flag has no meaning in the PCRpt and PCInitiate
message and SHOULD be set to 0 on transmission and MUST be ignored on message and MUST be set to 0 on transmission and MUST be ignored on
receipt. receipt.
4. Operation 4. Operation
During normal operation, a PCC that wishes to delegate the control of During normal operation, a PCC that wishes to delegate the control of
an LSP sets the D Flag (delegate) to 1 in all PCRpt messages an LSP sets the D Flag (delegate) to 1 in all PCRpt messages
pertaining to the LSP. The PCE confirms the delegation by setting D pertaining to the LSP. The PCE confirms the delegation by setting D
Flag to 1 in all PCUpd messages pertaining to the LSP. The PCC Flag to 1 in all PCUpd messages pertaining to the LSP. The PCC
revokes the control of the LSP from the PCE by setting D Flag to 0 in revokes the control of the LSP from the PCE by setting D Flag to 0 in
PCRpt messages pertaining to the LSP. If the PCE wishes to PCRpt messages pertaining to the LSP. If the PCE wishes to
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requests control is identified by the PLSP-ID. The PLSP-ID of 0 requests control is identified by the PLSP-ID. The PLSP-ID of 0
indicates that the PCE wants control over all LSPs originating from indicates that the PCE wants control over all LSPs originating from
the PCC. If the LSP(s) is/are already delegated to the PCE making the PCC. If the LSP(s) is/are already delegated to the PCE making
the request, the PCC ignores the C Flag. A PCC can decide to the request, the PCC ignores the C Flag. A PCC can decide to
delegate the control of the LSP at its own discretion. If the PCC delegate the control of the LSP at its own discretion. If the PCC
grants or denies the control, it sends PCRpt message with D Flag set grants or denies the control, it sends PCRpt message with D Flag set
to 1 and 0 respectively in accordance with according with stateful to 1 and 0 respectively in accordance with according with stateful
PCEP [RFC8231] . If the PCC does not grant the control, it MAY choose PCEP [RFC8231] . If the PCC does not grant the control, it MAY choose
to not respond, and the PCE may choose to retry requesting the to not respond, and the PCE may choose to retry requesting the
control preferably using exponentially increasing timer. A PCE control preferably using exponentially increasing timer. A PCE
ignores the C Flag on the PCRpt message. ignores the C Flag on the PCRpt message. Note that, the PCUpd
message with C flag set is received for a currently non-delegated LSP
(for which the PCE is requesting delegation), this MUST NOT trigger
the error handling as specified in [RFC8231] (a PCErr with Error-
type=19 (Invalid Operation) and error-value 1 (Attempted LSP Update
Request for a non-delegated LSP)).
In case multiple PCEs request control over an LSP, and if the PCC is In case multiple PCEs request control over an LSP, and if the PCC is
willing to grant the control, the LSP MUST be delegated to only one willing to grant the control, the LSP MUST be delegated to only one
PCE chosen by the PCC based on its local policy. PCE chosen by the PCC based on its local policy.
It should be noted that a legacy implementation of PCC, that does not It should be noted that a legacy implementation of PCC, that does not
understand the C flag in PCUpd message, would simply ignore the flag understand the C flag in PCUpd message, would simply ignore the flag
and the request to grant control over the LSP. (and the request to grant control over the LSP). At the same time it
would trigger the error condition as specified in [RFC8231] (a PCErr
with Error-type=19 (Invalid Operation) and error-value 1 (Attempted
LSP Update Request for a non-delegated LSP)).
[I-D.ietf-pce-pce-initiated-lsp] describes the setup, maintenance and [RFC8281] describes the setup, maintenance and teardown of PCE-
teardown of PCE-initiated LSPs under the stateful PCE model. It also initiated LSPs under the stateful PCE model. It also specify how a
specify how a PCE MAY obtain control over an orphaned LSP that was PCE MAY obtain control over an orphaned LSP that was PCE-initiated.
PCE-initiated. A PCE implementation can apply the mechanism A PCE implementation can apply the mechanism described in this
described in this document in conjunction with those in document in conjunction with those in [RFC8281].
[I-D.ietf-pce-pce-initiated-lsp].
5. Security Considerations 5. Security Considerations
The security considerations listed in [RFC8231] apply to this The security considerations listed in [RFC8231] apply to this
document as well. However, this document also introduces a new document as well. However, this document also introduces a new
attack vectors. An attacker may flood the PCC with request to attack vectors. An attacker may flood the PCC with request to
delegate all its LSPs at a rate which exceeds the PCC's ability to delegate all its LSPs at a rate which exceeds the PCC's ability to
process them, either by spoofing messages or by compromising the PCE process them, either by spoofing messages or by compromising the PCE
itself. The PCC can simply ignore these messages with no extra itself. The PCC can simply ignore these messages with no extra
actions. Securing the PCEP session using mechanism like Transport actions. Securing the PCEP session using mechanism like Transport
Layer Security (TLS) [RFC8253] is RECOMMENDED. Layer Security (TLS) [RFC8253] is RECOMMENDED.
6. IANA Considerations 6. IANA Considerations
This document requests IANA actions to allocate code points for the This document requests IANA actions to allocate code points for the
protocol elements defined in this document. protocol elements defined in this document.
6.1. SRP Object Flags 6.1. SRP Object Flags
The SRP object is defined in [RFC8231] and the registry to manage the The SRP object is defined in [RFC8231] and the registry to manage the
Flag field of the SRP object is requested in Flag field of the SRP object is requested in [RFC8281]. IANA is
[I-D.ietf-pce-pce-initiated-lsp]. IANA is requested to make the requested to make the following allocation in the aforementioned
following allocation in the aforementioned registry. registry.
Bit Description Reference Bit Description Reference
TBD LSP Control Request Flag (c-bit) This document TBD LSP Control Request Flag (c-bit) This document
7. Manageability Considerations 7. Manageability Considerations
All manageability requirements and considerations listed in [RFC5440] All manageability requirements and considerations listed in [RFC5440]
and [RFC8231] apply to PCEP protocol extensions defined in this and [RFC8231] apply to PCEP protocol extensions defined in this
document. In addition, requirements and considerations listed in document. In addition, requirements and considerations listed in
this section apply. this section apply.
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[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8231] Crabbe, E., Minei, I., Medved, J., and R. Varga, "Path [RFC8231] Crabbe, E., Minei, I., Medved, J., and R. Varga, "Path
Computation Element Communication Protocol (PCEP) Computation Element Communication Protocol (PCEP)
Extensions for Stateful PCE", RFC 8231, Extensions for Stateful PCE", RFC 8231,
DOI 10.17487/RFC8231, September 2017, DOI 10.17487/RFC8231, September 2017,
<https://www.rfc-editor.org/info/rfc8231>. <https://www.rfc-editor.org/info/rfc8231>.
9.2. Informative References [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>.
[I-D.ietf-pce-pce-initiated-lsp] 9.2. Informative References
Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "PCEP
Extensions for PCE-initiated LSP Setup in a Stateful PCE
Model", draft-ietf-pce-pce-initiated-lsp-11 (work in
progress), October 2017.
[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-06 (work in progress), January 2018. yang-07 (work in progress), March 2018.
[RFC4657] Ash, J., Ed. and J. Le Roux, Ed., "Path Computation [RFC4657] Ash, J., Ed. and J. Le Roux, Ed., "Path Computation
Element (PCE) Communication Protocol Generic Element (PCE) Communication Protocol Generic
Requirements", RFC 4657, DOI 10.17487/RFC4657, September Requirements", RFC 4657, DOI 10.17487/RFC4657, September
2006, <https://www.rfc-editor.org/info/rfc4657>. 2006, <https://www.rfc-editor.org/info/rfc4657>.
[RFC8051] Zhang, X., Ed. and I. Minei, Ed., "Applicability of a [RFC8051] Zhang, X., Ed. and I. Minei, Ed., "Applicability of a
Stateful Path Computation Element (PCE)", RFC 8051, Stateful Path Computation Element (PCE)", RFC 8051,
DOI 10.17487/RFC8051, January 2017, DOI 10.17487/RFC8051, January 2017,
<https://www.rfc-editor.org/info/rfc8051>. <https://www.rfc-editor.org/info/rfc8051>.
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