Ability for a stateful PCE to request and obtain control of LSP
draft-raghu-pce-lsp-control-request-00
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft whose latest revision state is "Replaced".
|
|
|---|---|---|---|
| Authors | Aswatnarayan Raghuram , Al Goddard , Chaitanya Yadlapalli , Jay Karthik , Siva Sivabalan , Jon Parker | ||
| Last updated | 2016-05-11 | ||
| Replaced by | draft-ietf-pce-lsp-control-request, draft-ietf-pce-lsp-control-request, draft-ietf-pce-lsp-control-request, draft-ietf-pce-lsp-control-request, RFC 8741 | ||
| RFC stream | (None) | ||
| Formats | |||
| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
| RFC Editor Note | (None) | ||
| IESG | IESG state | I-D Exists | |
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | (None) |
draft-raghu-pce-lsp-control-request-00
PCE Working Group A. Raghuram
Internet-Draft A. Goddard
Intended status: Standards Track C. Yadlapalli
Expires: November 12, 2016 AT&T
J. Karthik
S. Sivabalan
J. Parker
Cisco Systems, Inc.
May 11, 2016
Ability for a stateful PCE to request and obtain control of LSP
draft-raghu-pce-lsp-control-request-00.txt
Abstract
The stateful PCEP extensions provide stateful control of
Multiprotocol Label Switching (MPLS) Traffic Engineering Label
Switched Paths (TE LSP) via PCEP, for a model where a PCC delegates
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
obtain control of one or more LSPs from a PCC. This document
describes a simple extension to stateful PCEP to achieve such
objective.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
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
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on November 12, 2016.
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Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. LSP Control Request Flag . . . . . . . . . . . . . . . . . . 3
4. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . 5
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5
8. Normative References . . . . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction
Stateful PCEP extensions [I-D.ietf-pce-stateful-pce] specifies a set
of extensions to PCEP to enable stateful control of TE LSPs between
and across PCEP sessions in compliance with [RFC4657]. It includes
mechanisms to effect LSP state synchronization between PCCs and PCEs,
delegation of control of LSPs to PCEs, and PCE control of timing and
sequence of path computations within and across PCEP sessions. The
stateful PCEP defines the following two useful network operations:
o Delegation: an operation in which a PCC temporarily grants the
rights to modify one or more LSPs to a PCE, and such LSPs are
referred to as delegated LSPs.
o Revocation: an operation in which a PCC revokes the previously
granted rights to modify one or more LSPs from a PCE.
Some network operators prefer head-end (PCC) based reactivity to
network events (e.g., link failure). For example, typically
operators would like to reduce the time that backup LSP are being
used for fast-reroute protection as the links that a backup LSP
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traverses may be congested when fast-reroute is active. PCC based
LSP failure detection and re-routing mechanisms enable operators to
minimize the duration of such congestion and meet operational
requirements/constraints. As such, during normal operations, it may
be preferable for PCC to have full control of its LSPs. However,
operators shall prefer to use PCE for planned events such as
centralized optimization and placement of LSPs. In this case, it is
preferable for a PCE to obtain the control of one or more LSPs from a
PCC, rather than waiting for the PCC to delegate the control. Once
the PCE completes its operation, it reliqushes the control of the
LSPs. Such capability enables operatirs to combine the benefits of
both centralized and distributed control of TE LSPs to get the best
of both worlds.
This specification provides a simple extension using which a PCE can
request control of one or more LSPs from any PCC over stateful PCEP
channel. The procedures for granting and relinquishing control of
the LSPs are specified in accordance with the specification
[I-D.ietf-pce-stateful-pce].
2. Terminology
The following terminologies are used in this document:
PCC: Path Computation Client.
PCE: Path Computation Element
PCEP: Path Computation Element Protocol.
PCRpt: PCEP report message.
PCUpd: PCEP update message.
PLSP-ID: A PCEP-specific identifier for the LSP.
3. LSP Control Request Flag
The LSP object is defined in [I-D.ietf-pce-stateful-pce] and
included here for ease of reference.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PLSP-ID |Flags|G|C| O|A|R|S|D|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLVs |
~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: The LSP Object
A new flag, the "LSP Control Request Flag" (G), is introduced. On a
PCUpd message, a PCE sets the G Flag to 1 to indicate that it wishes
to gain control of LSP(s). A PLSP-ID of value other than 0 and
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 of all LSPs originating from the PCC.
4. Operation
During normal operation, a PCC that wishes to delegate the control of
an LSP sets the D Flag to 1 in all PCRpt messages 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 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 relinquish the control
of the LSP, it sets D Flag to 0 in all PCUpd messages pertaining to
the LSP.
If a PCE wishes to gain control over an LSP, it sends a PCUpd message
with G Flag set to 1. The LSP for which the PCE requests control is
identified by the PLSP-ID. The PLSP-ID of 0 indicates that the PCE
wants control over all LSPs originating from the PCC. If the LSP(s)
is/are already delegated to the PCE, the PCC ignores the G Flag. A
PCC can decide to 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 to 1 and 0 respectively in accordance with
according with stateful PCEP [I-D.ietf-pce-stateful-pce] . If the PCC
does not grant the control, the PCE may choose to retry requesting
the control preferably using exponentially increasing timer. A PCE
ignores the G Flag on PCRpt message
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
PCE chosen by the PCC based on its local policy.
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5. Security Considerations
No additional security measure is required.
6. IANA Considerations
None.
7. Acknowledgements
TBD.
8. Normative References
[I-D.ietf-pce-stateful-pce]
Crabbe, E., Minei, I., Medved, J., and R. Varga, "PCEP
Extensions for Stateful PCE", draft-ietf-pce-stateful-
pce-14 (work in progress), March 2016.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC4657] Ash, J., Ed. and J. Le Roux, Ed., "Path Computation
Element (PCE) Communication Protocol Generic
Requirements", RFC 4657, DOI 10.17487/RFC4657, September
2006, <http://www.rfc-editor.org/info/rfc4657>.
[RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
Element (PCE) Communication Protocol (PCEP)", RFC 5440,
DOI 10.17487/RFC5440, March 2009,
<http://www.rfc-editor.org/info/rfc5440>.
Authors' Addresses
Aswatnarayan Raghuram
AT&T
200 S Laurel Aevenue
Middletown, NJ 07748
USA
Email: ar2521@att.com
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Al Goddard
AT&T
200 S Laurel Aevenue
Middletown, NJ 07748
USA
Email: ag6941@att.com
Chaitanya Yadlapalli
AT&T
200 S Laurel Aevenue
Middletown, NJ 07748
USA
Email: cy098d@att.com
Jay Karthik
Cisco Systems, Inc.
125 High Street
Boston, Massachusetts 02110
USA
Email: jakarthi@cisco.com
Siva Sivabalan
Cisco Systems, Inc.
2000 Innovation Drive
Kanata, Ontario K2K 3E8
Canada
Email: msiva@cisco.com
Jon Parker
Cisco Systems, Inc.
2000 Innovation Drive
Kanata, Ontario K2K 3E8
Canada
Email: jdparker@cisco.com
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