PCE Working Group C. Barth
Internet-Draft R. Torvi
Intended status: Standards Track Juniper Networks
Expires: January 7, 2016 P. Bedard
Cox Communications
July 6, 2015
PCEP Extensions for RSVP-TE Local-Protection with PCE-Stateful
draft-cbrt-pce-stateful-local-protection-00
Abstract
Stateful PCE [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 local
protection paths to also be computed by the PCE. This document
defines extensions needed for the setup and management of RSVP-TE
protection paths by the PCE.
Status of This Memo
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This Internet-Draft will expire on January 7, 2016.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Architectural Overview . . . . . . . . . . . . . . . . . . . 3
3.1. Local Protection Overview . . . . . . . . . . . . . . . . 3
4. Extensions for the LSPA object . . . . . . . . . . . . . . . 4
4.1. The Weight TLV . . . . . . . . . . . . . . . . . . . . . 4
4.2. The Bypass TLV . . . . . . . . . . . . . . . . . . . . . 4
4.3. The LOCALLY-PROTECTED-LSPS TLV . . . . . . . . . . . . . 5
5. IANA considerations . . . . . . . . . . . . . . . . . . . . . 7
5.1. PCEP-Error Object . . . . . . . . . . . . . . . . . . . . 7
5.2. PCEP TLV Type Indicators . . . . . . . . . . . . . . . . 7
6. Security Considerations . . . . . . . . . . . . . . . . . . . 7
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
8.1. Normative References . . . . . . . . . . . . . . . . . . 7
8.2. Informative References . . . . . . . . . . . . . . . . . 8
Appendix A. Additional Stuff . . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
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 Multi-protocol Label Switching (MPLS) for Traffic
Engineering Label Switched Path (TE LSP) characteristics.
Stateful PCE [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
and allow delegation of control of LSPs to PCEs.
In a network where all LSPs have control delegated to a PCE, the PCE
can apply global concurrent optimization to optimize LSP placement.
The PCE can also control the timing and sequence of path computation
and applying path changes. 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.
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Benefits of stateful syncrhonization and control of the protection
paths include:
o Better control over traffic after a failure and more deterministic
path computation of protection paths. The PCE can optimize the
protection path based on data not available to the PCC, for instance
the PCE can make sure the protection path will not violate the delay
specified by [I-D.ietf-pce-pcep-service-aware].
o Satisfy more complex constraints and diversity requirements, such
as maintaining diverse paths for LSPs as well as their local
protection paths.
o Given the PCE's global view of network resources, act as a form of
LSP admission control into a protection path to ensure links are not
overloaded during failure events.
o On a PLR with multiple available protection routes, allows the PCE
to map LSPs to all available protection routes versus a single best
protection route.
o Most of the benefits stated in the stateful PCE applicability draft
[I-D.ietf-pce-stateful-pce-app-04] apply equally to protection paths.
2. Terminology
This document uses the following terms defined in [RFC5440] PCC PCE,
PCEP Peer.
This document uses the following terms defined in Stateful PCE
[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. 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) N:1 protection - the protection path protects multiple LSPs
traversing the protected resource.
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It is assumed that the PCE knows what resources require protection
through mechanisms outside the scope of this document. In a PCE
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 discussed only
for the N:1 case.
Local protection requires the setup of a bypass at the PLR. This
bypass can be PCC-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. There
two types Bypass LSPs mappings:
(1) Independent Bypass LSP Mapping: In this case Bypass LSP mapping
is handled by a local policy on PCC and the PCC reports all mappings
to the PCE. In other words, bypass LSP(s) are mapped to any
protected LSP(s) that satisfy PCC local policy.
(2) Dependent Bypass LSP mapping: 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 4.3. 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 Weight TLV
This TLV will be discussed in a future version of this document.
4.2. 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 PCE-Initated LSP
[ietf-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.
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The format of the IPv4 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 2
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=[TBD] | Length=8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MUST be zero | Flags |I|N|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Bypass IPv4 Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: IPv4 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:
Flags (16 bit)
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)
4.3. The LOCALLY-PROTECTED-LSPS TLV
The IPV4-LOCALLY-PROTECTED-LSPS TLV in the LSPA Object contains a
list of LSPs protected by the bypass tunnel.
The format of the Locally protected LSPs 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 2
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 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 2: IPv4 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: As defined in [RFC3209],
Section 4.6.1.1
Flags (16 bit)
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: As defined in [RFC3209], Section 4.6.1.1
Extended Tunnel ID: As defined in [RFC3209], Section 4.6.2.1
IPv4 Tunnel Sender address: As defined in [RFC3209], Section 4.6.2.1
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LSP ID: As defined in RFC 3209
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 |
+---------+------------------------+---------------+
Table 1: New PCEP TLVs
6. Security Considerations
The same security considerations apply at the PLR as those describe
for the head end in PCE Initiated LSPs [ietf-pce-pce-initiated-lsp].
7. Acknowledgements
We would like to thank Ambrose Kwong for his contributions to this
document.
8. References
8.1. Normative References
[ietf-pce-pce-initiated-lsp]
Crabbe, E., Sivabalan, S., and R. Verga, "PCEP Extensions
for PCE-initiated LSP Setup in a Stateful PCE Model",
2014.
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[ietf-pce-stateful-pce]
Crabbe, E., Medved, J., Minie, I., and R. Verga, "PCEP
Extensions for Stateful PCE", 2015.
[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", September 1997.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", December 2001.
[RFC4090] Pan, P., Swallow, G., and A. Atlas, "Fast Reroute
Extensions to RSVP-TE for LSP Tunnels", May 2005.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", May 2008.
[RFC5440] Vasseur, JP. and JL. Le Roux, "Path Computation Element
(PCE) Communication Protocol (PCEP)", March 2009.
8.2. Informative References
[I-D.narten-iana-considerations-rfc2434bis]
Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", draft-narten-iana-
considerations-rfc2434bis-09 (work in progress), March
2008.
[RFC2629] Rose, M., "Writing I-Ds and RFCs using XML", RFC 2629,
June 1999.
[RFC3552] Rescorla, E. and B. Korver, "Guidelines for Writing RFC
Text on Security Considerations", BCP 72, RFC 3552, July
2003.
[RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation
Element (PCE)-Based Architecture", August 2006.
[RFC4657] Ash, J. and J. Le Roux, "Path Computation Element (PCE)
Communication Protocol Generic Requirements", September
2006.
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[RFC5394] Bryskin, I., Papadimitriou, D., Berger, L., and J. Ash,
"Policy-Enabled Path Computation Framework", 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", July 2009.
Appendix A. Additional Stuff
This becomes an Appendix.
Authors' Addresses
Colby Barth
Juniper Networks
Sunnyvale, CA
USA
Email: cbarth@juniper.net
Raveendra Torvi
Juniper Networks
Sunnyvale, CA
USA
Email: rtorvi@juniper.net
Phil Bedard
Cox Communications
Atlanta, GA
USA
Email: Phil.Bedard@cox.com
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