Internet DRAFT - draft-crabbe-pce-stateful-pce-protection
draft-crabbe-pce-stateful-pce-protection
Network Working Group E. Crabbe
Internet-Draft Google, Inc.
Intended status: Standards Track J. Medved
Expires: April 15, 2013 Cisco Systems, Inc.
I. Minei
R. Torvi
Juniper Networks, Inc.
October 12, 2012
PCEP Extensions for MPLS-TE LSP protection with stateful PCE
draft-crabbe-pce-stateful-pce-protection-00
Abstract
Stateful PCE [I-D.ietf-pce-stateful-pce] can apply global concurrent
optimizations to optimize LSP placement. In a deployment where a PCE
is used to compute all the paths, it may be beneficial for the
protection paths to also be computed by the PCE. This document
defines extensions needed for the setup and management of MPLS-TE
protection paths by the PCE.
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 April 15, 2013.
Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the
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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
publication of this document. Please review these documents
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Architectural Overview . . . . . . . . . . . . . . . . . . . . 3
3.1. Path Protection Overview . . . . . . . . . . . . . . . . . 3
3.2. Local Protection Overview . . . . . . . . . . . . . . . . 4
4. Extensions for the LSPA object . . . . . . . . . . . . . . . . 5
4.1. The Standby flag in the LSPA object . . . . . . . . . . . 5
4.2. The Weight TLV . . . . . . . . . . . . . . . . . . . . . . 6
4.3. The Bypass TLV . . . . . . . . . . . . . . . . . . . . . . 6
4.4. The LOCALLY-PROTECTED-LSPS TLV . . . . . . . . . . . . . . 7
5. IANA considerations . . . . . . . . . . . . . . . . . . . . . 9
5.1. PCEP-Error Object . . . . . . . . . . . . . . . . . . . . 9
5.2. PCEP TLV Type Indicators . . . . . . . . . . . . . . . . . 9
6. Security Considerations . . . . . . . . . . . . . . . . . . . 9
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 9
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
8.1. Normative References . . . . . . . . . . . . . . . . . . . 10
8.2. Informative References . . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11
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1. Introduction
[RFC5440] describes the Path Computation Element Protocol PCEP. PCEP
defines the communication between a Path Computation Client (PCC) and
a Path Control Element (PCE), or between PCE and PCE, enabling
computation of Multiprotocol Label Switching (MPLS) for Traffic
Engineering Label Switched Path (TE LSP) characteristics.
Stateful pce [I-D.ietf-pce-stateful-pce] specifies a set of
extensions to PCEP to enable stateful control of paths such as MPLS
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 and focuses on a model where LSPs are
configured on the PCC and control over them is delegated to the PCE.
Stateful PCE can apply global concurrent optimizations to optimize
LSP placement. In a deployment where a PCE is used to compute all
the paths, it may be beneficial for the protection paths to also be
controlled through the PCE. This document defines extensions needed
for the setup and management of protection paths by the PCE.
Benefits of controlling the protection paths include: better control
over traffic after a failure and more deterministic path computation
(paths not affected by overload after a failure).
2. Terminology
This document uses the following terms defined in [RFC5440]: PCC,
PCE, PCEP Peer.
This document uses the following terms defined in
[I-D.ietf-pce-stateful-pce]: Stateful PCE, Delegation, Delegation
Timeout Interval, LSP State Report, LSP Update Request.
The message formats in this document are specified using Routing
Backus-Naur Format (RBNF) encoding as specified in [RFC5511].
3. Architectural Overview
3.1. Path Protection Overview
Path protection refers to switching to a new path on failure.
Several cases exist:
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(1) MPLS-TE Global Default Restoration - protection paths are
computed dynamically by the LSR after the failure. This can be
supported without any PCEP protocol changes by specifying a
secondary path with an ERO of just the end points of the LSP.
Once reestablished, the path is communicated to the PCE via the
LSP State Report message.
(2) MPLS-TE Global Path Protection - protection paths are fully
specified ahead of the failure. The base Stateful PCE
specification [I-D.ietf-pce-stateful-pce] supports sending
multiple fully-specified paths in the PCUpd requests.There are 2
further sub-cases:
(a) Protection paths are pre-signaled ahead of the failure
(standby paths).
(b) Protection paths are set up after the failure.
The protection path setup regimen (standby or not) is specified in
the path using a new per-path flag in the LSPA object, the S
(standby) flag (see section Section 4.1). Paths for which the S flag
is set MUST have a name associated with them, specified using the
SYMBOLIC-PATH-NAME TLV in the LSPA object.
Because multiple secondary standby paths are possible, there is also
a need for the PCE to be able to specify the relative priorities
between the paths (which one to take if there are 3 available). This
is done through a weight assigned to each path. See details in
Section 4.2.
Reversion from protection paths to the primary path when possible
will be controlled by the PCE, by sending a new LSP Update Request.
If the primary can be successfully signaled and the secondary does
not have the S flag set, then the secondary MUST be torn down. Thus,
there is no need to signal the desire for revertive behavior.
3.2. Local Protection Overview
Local protection refers to the ability to locally route around
failure of an LSP. Two types of local protection are possible:
(1) 1:1 protection - the protection path protects a single LSP.
(2) 1:N protection - the protection path protects multiple LSPs
traversing the protected resource.
It is assumed that the PCE knows what resources require protection
through mechanisms outside the scope of this document. In a PCE-
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controlled deployment, support of 1:1 protection has limited
applicability, and can be achieved as a degenerate case of 1:N
protection. For this reason, local protection will be disccussed
only for the 1:N case.
Local protection requires the setup of a bypass at the PLR. This
bypass can be locally initiated and delegated, or PCE-initiated. In
either case, the PLR must maintain a PCEP session to the PCE. A
bypass identifier (the name of the bypass) is required for
disambiguation as multiple bypasses are possible at the PLR. Mapping
of LSPs to bypass is done through a new TLV, the LOCALLY-PROTECTED-
LSPS TLV in the LSP Update message from PCE to PLR. See section
Section 4.4. When an LSP requiring protection is set up through the
PLR, the PLR checks if it has a mapping to a bypass and only provides
protection if such a mapping exists. The status of bypasses and what
LSPs are protected by them is communicated to the PCE via LSP Status
Report messages.
4. Extensions for the LSPA object
4.1. The Standby flag in the LSPA object
The LSPA object is defined in [RFC5440] and replicated below for easy
reference. This document defines a new flag, the S flag in the flags
field of the LSPA object.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Exclude-any |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Include-any |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Include-all |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Setup Prio | Holding Prio | Flags |S|L| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Optional TLVs //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: STATEFUL-PCE-CAPABILITY TLV format
The L flag is defined in [RFC5440].
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If set to 1, the S Flag indicates this is a standby path.
If the S flag is set, the LSPA object MUST also carry the SYMBOLIC-
PATH-NAME TLV as one of the optional TLVs. Failure to include the
mandatory SYMBOLIC-PATH-NAME TLV when the S flag is set MUST trigger
PCErr of type 6 (Mandatory Object missing) and value TBD (SYMBOLIC-
PATH-NAME TLV missing for standby LSP).
4.2. The Weight TLV
This TLV will be discussed in a future version of tihs document.
4.3. The Bypass TLV
The facility backup method creates a bypass tunnel to protect a
potential failure point. The bypass tunnel protects a set of LSPs
with similar backup constraints {RFC4090].
A PCC can delegate a bypass tunnel to PCE control or a PCE can
provision the bypass tunnel via a PCC. The procedures for bypass
instantiation rely on the extensions defined in
[I-D.crabbe-pce-pce-initiated-lsp] and will be detailed in a future
version of this document.
The Bypass TLV carries information about the bypass tunnel. It is
included in the LSPA Object in LSP State Report and LSP Update
Request messages.
The format of the Bypass TLV is shown in the following figure:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=[TBD] | Length=8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MUST be zero | Flags |I|N|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Bypass IPv4 Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Bypass TLV format
The type of the TLV is [TBD] and it has a fixed length of 8 octets.
The value contains the following fields:
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Flags
N (Node Protection - 1 bit): The N Flag indicates whether the
Bypass is used for node-protection. If the N flag is set to 1,
the Bypass is used for node-protection. If the N flag is 0,
the Bypass is used for link-protection.
I (Local Protection In Use - 1 bit): The I Flag indicates that
local repair mechanism is in use.
Bypass IPv4 address: For link protection, the Bypass IPv4 Address is
the nexthop address of the protected link in the paths of the
protected LSPs. For node protection, the Bypass IPv4 Address is
the node addresses of the protected node.
If the Bypass TLV is included, then the LSPA object MUST also carry
the SYMBOLIC-PATH-NAME TLV as one of the optional TLVs. Failure to
include the mandatory SYMBOLIC-PATH-NAME TLV MUST trigger PCErr of
type 6 (Mandatory Object missing) and value TBD (SYMBOLIC-PATH-NAME
TLV missing for bypass LSP)
4.4. The LOCALLY-PROTECTED-LSPS TLV
The LOCALLY-PROTECTED-LSPS TLV in the LSPA Object contains a list of
LSPs protected by the bypass tunnel.
The format of the Bypass TLV is shown in the following figure:
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=[TBD] | Length (variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 tunnel end point address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags |R| Tunnel ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Extended Tunnel ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 Tunnel Sender Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MUST be zero | LSP ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// .... //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 tunnel end point address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags |R| Tunnel ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Extended Tunnel ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 Tunnel Sender Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MUST be zero | LSP ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: Locally protected LSPs TLV format
The type of the TLV is [TBD] and it is of variable length.The value
contains one or more LSP descriptors including the following fields
filled per [RFC3209].
IPv4 Tunnel end point address: [RFC3209]
Flags
R(Remove - 1 bit): The R Flag indicates that the LSP has been
removed from the list of LSPs protected by the bypass tunnel.
Tunnel ID: [RFC3209]
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Extended Tunnel ID: [RFC3209]
IPv4 Tunnel Sender address: [RFC3209]
LSP ID: [RFC3209]
5. IANA considerations
5.1. PCEP-Error Object
This document defines new Error-Type and Error-Value for the
following new error conditions:
Error-Type Meaning
6 Mandatory Object missing
Error-value=TBD: SYMBOLIC-PATH-NAME TLV missing for a
path where the S-bit is set in the LSPA
object.
Error-value=TBD: SYMBOLIC-PATH-NAME TLV missing for a
bypass path.
5.2. PCEP TLV Type Indicators
This document defines the following new PCEP TLVs:
Value Meaning Reference
??? Bypass This document
??? weight This document
??? LOCALLY-PROTECTED-LSPS This document
6. Security Considerations
The same security considerations apply at the PLR as those describe
for the head end in [I-D.crabbe-pce-pce-initiated-lsp].
7. Acknowledgements
We would like to thank Ambrose Kwong for his contributions to this
document.
8. References
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8.1. Normative References
[I-D.crabbe-pce-pce-initiated-lsp]
Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "PCEP
Extensions for PCE-initiated LSP Setup in a Stateful PCE
Model", draft-crabbe-pce-pce-initiated-lsp-00 (work in
progress), October 2012.
[I-D.ietf-pce-stateful-pce]
Crabbe, E., Medved, J., Varga, R., and I. Minei, "PCEP
Extensions for Stateful PCE",
draft-ietf-pce-stateful-pce-01 (work in progress),
July 2012.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2205] Braden, B., Zhang, L., Berson, S., Herzog, S., and S.
Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1
Functional Specification", RFC 2205, September 1997.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, December 2001.
[RFC4090] Pan, P., Swallow, G., and A. Atlas, "Fast Reroute
Extensions to RSVP-TE for LSP Tunnels", RFC 4090,
May 2005.
[RFC5088] Le Roux, JL., Vasseur, JP., Ikejiri, Y., and R. Zhang,
"OSPF Protocol Extensions for Path Computation Element
(PCE) Discovery", RFC 5088, January 2008.
[RFC5089] Le Roux, JL., Vasseur, JP., Ikejiri, Y., and R. Zhang,
"IS-IS Protocol Extensions for Path Computation Element
(PCE) Discovery", RFC 5089, January 2008.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008.
[RFC5440] Vasseur, JP. and JL. Le Roux, "Path Computation Element
(PCE) Communication Protocol (PCEP)", RFC 5440,
March 2009.
[RFC5511] Farrel, A., "Routing Backus-Naur Form (RBNF): A Syntax
Used to Form Encoding Rules in Various Routing Protocol
Specifications", RFC 5511, April 2009.
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8.2. Informative References
[RFC2702] Awduche, D., Malcolm, J., Agogbua, J., O'Dell, M., and J.
McManus, "Requirements for Traffic Engineering Over MPLS",
RFC 2702, September 1999.
[RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol
Label Switching Architecture", RFC 3031, January 2001.
[RFC3346] Boyle, J., Gill, V., Hannan, A., Cooper, D., Awduche, D.,
Christian, B., and W. Lai, "Applicability Statement for
Traffic Engineering with MPLS", RFC 3346, August 2002.
[RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering
(TE) Extensions to OSPF Version 2", RFC 3630,
September 2003.
[RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation
Element (PCE)-Based Architecture", RFC 4655, August 2006.
[RFC4657] Ash, J. and J. Le Roux, "Path Computation Element (PCE)
Communication Protocol Generic Requirements", RFC 4657,
September 2006.
[RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic
Engineering", RFC 5305, October 2008.
[RFC5394] Bryskin, I., Papadimitriou, D., Berger, L., and J. Ash,
"Policy-Enabled Path Computation Framework", RFC 5394,
December 2008.
[RFC5557] Lee, Y., Le Roux, JL., King, D., and E. Oki, "Path
Computation Element Communication Protocol (PCEP)
Requirements and Protocol Extensions in Support of Global
Concurrent Optimization", RFC 5557, July 2009.
Authors' Addresses
Edward Crabbe
Google, Inc.
1600 Amphitheatre Parkway
Mountain View, CA 94043
US
Email: edc@google.com
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Jan Medved
Cisco Systems, Inc.
170 West Tasman Dr.
San Jose, CA 95134
US
Email: jmedved@cisco.com
Ina Minei
Juniper Networks, Inc.
1194 N. Mathilda Ave.
Sunnyvale, CA 94089
US
Email: ina@juniper.net
Raveendra Torvi
Juniper Networks, Inc.
1194 N. Mathilda Ave.
Sunnyvale, CA 94089
US
Email: rtorvi@juniper.net
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