Internet DRAFT - draft-cbrt-pce-stateful-local-protection
draft-cbrt-pce-stateful-local-protection
PCE Working Group C. Barth
Internet-Draft R. Torvi
Intended status: Standards Track Juniper Networks
Expires: December 30, 2018 June 28, 2018
PCEP Extensions for RSVP-TE Local-Protection with PCE-Stateful
draft-cbrt-pce-stateful-local-protection-01
Abstract
Stateful PCE [RFC8231] 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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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on December 30, 2018.
Copyright Notice
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
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 Preference TLV . . . . . . . . . . . . . . . . . . . 4
4.2. The Bypass TLV . . . . . . . . . . . . . . . . . . . . . 5
4.3. The LOCALLY-PROTECTED-LSPS TLV . . . . . . . . . . . . . 6
5. IANA considerations . . . . . . . . . . . . . . . . . . . . . 8
5.1. PCEP-Error Object . . . . . . . . . . . . . . . . . . . . 8
5.2. PCEP TLV Type Indicators . . . . . . . . . . . . . . . . 8
6. Security Considerations . . . . . . . . . . . . . . . . . . . 8
7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 8
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
8.1. Normative References . . . . . . . . . . . . . . . . . . 9
8.2. Informative References . . . . . . . . . . . . . . . . . 9
Appendix A. Additional Stuff . . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
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 [RFC8231] 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 synchronization 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 [RFC8231] 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 Preference TLV
When provisioning a PCC, the PCE can influence primary to bypass LSP
association of the PCC using the preference TLV. Bypass LSPs with a
higher preference are used first during primary LSP association.
Bypass LSPs with identical preferences are used for primary
association according to local PCC selection.
The format of the IPv4 Preference 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 | Preference |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Figure 1: IPv4 Preference TLV format
The type of the TLV is [TBD] and it has a fixed length of 8 octets.
The value contains the following fields:
Preference (8 bits): The value indicates the bypass LSP preference
during the primary LSP selection process of the PCC. A lower
preference value is preferred to a higher value with a default value
of 255. A value of 0 would indicate that the bypass is not to be
selected for any primary LSP associations.
If the Preference 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).
4.2. 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 [RFC8281] and will be
detailed in a future version of this document.
A subscription multiplier can be used to influence the local PCC
admission control during primary LSP association. This allows for
under subscription or oversubscription policy to be applied to the
bandwidth attribute of the bypass LSP.
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 IPv4 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 2
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=[TBD] | Length=8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MUST be zero | Flags |I|N|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Bypass IPv4 Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Subscription Multiplier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: 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: The Bypass IPv4 Address is the next-hop address
of the protected link in the paths of the protected LSPs.
Subscription Multiplier (32 bits): An optional multiplier represented
as a floating point number. The value may be used to influence CAC
during primary LSP association. For example, a bypass may reserved
50M but the PCC may want to admit up to (multiplier * reserved
bandwidth) to the bypass LSP.
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.
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The format of the Locally protected LSPs 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 (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: 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
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IPv4 Tunnel Sender address: As defined in [RFC3209], Section 4.6.2.1
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 [RFC8281].
7. Contributors
The following people have substantially contributed to the editing of
this document:
Harish Sitaraman, Juniper Networks, hsitaraman@juniper.net
Vishnu Pavan Beeram, Juniper Networks, vbeeram@juniper.net
Chandrasekar Ramachandran, Juniper Networks, csekar@juniper.net
Ambrose Kwong, Juniper Networks, akwong@juniper.net
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Phil Bedard, bedard.phil@gmail.com
8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[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.
[RFC8231] Crabbe, E., Medved, J., Minie, I., and R. Verga, "PCEP
Extensions for Stateful PCE", 2015.
[RFC8281] Crabbe, E., Sivabalan, S., and R. Verga, "PCEP Extensions
for PCE-initiated LSP Setup in a Stateful PCE Model",
2014.
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,
DOI 10.17487/RFC2629, June 1999,
<https://www.rfc-editor.org/info/rfc2629>.
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[RFC3552] Rescorla, E. and B. Korver, "Guidelines for Writing RFC
Text on Security Considerations", BCP 72, RFC 3552,
DOI 10.17487/RFC3552, July 2003,
<https://www.rfc-editor.org/info/rfc3552>.
[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.
[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
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