PCE Working Group I. Minei
Internet-Draft Google, Inc.
Intended status: Standards Track E. Crabbe
Expires: January 8, 2017
S. Sivabalan
Cisco Systems, Inc.
H. Ananthakrishnan
Packet Design
X. Zhang
Huawei Technologies
Y. Tanaka
NTT Communications Corporation
July 7, 2016
PCEP Extensions for Establishing Relationships Between Sets of LSPs
draft-ietf-pce-association-group-01
Abstract
This document introduces a generic mechanism to create a grouping of
LSPs in the context of a PCE. This grouping can then be used to
define associations between sets of LSPs or between a set of LSPs and
a set of attributes (such as configuration parameters or behaviors),
and is equally applicable to the active and passive modes of a
stateful PCE as well as a stateless 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."
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This Internet-Draft will expire on January 8, 2017.
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
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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. Motivation . . . . . . . . . . . . . . . . . . . . . . . 3
3.2. Operation Overview . . . . . . . . . . . . . . . . . . . 4
4. ASSOCIATION Object . . . . . . . . . . . . . . . . . . . . . 4
4.1. Object Definition . . . . . . . . . . . . . . . . . . . . 4
4.1.1. Global Association Source TLV . . . . . . . . . . . . 6
4.1.2. Extended Association ID TLV . . . . . . . . . . . . . 6
4.2. Object Encoding in PCEP messages . . . . . . . . . . . . 7
4.3. Processing Rules . . . . . . . . . . . . . . . . . . . . 9
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
6. Security Considerations . . . . . . . . . . . . . . . . . . . 11
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 11
8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 11
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 11
9.1. Normative References . . . . . . . . . . . . . . . . . . 11
9.2. Informative References . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12
1. Introduction
[RFC5440] describes the Path Computation Element Protocol PCEP. PCEP
enables the communication between a Path Computation Client (PCC) and
a Path Control Element (PCE), or between PCE and PCE, for the purpose
of computation of Multiprotocol Label Switching (MPLS) as well as
Generalzied MPLS (GMPLS) for Traffic Engineering Label Switched Path
(TE LSP) characteristics.
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Stateful pce [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] and focuses on a
model where LSPs are configured on the PCC and control over them is
delegated to the PCE. The model of operation where LSPs are
initiated from the PCE is described in
[I-D.ietf-pce-pce-initiated-lsp].
This document introduces a generic mechanism to create a grouping of
LSPs. This grouping can then be used to define associations between
sets of LSPs or between a set of LSPs and a set of attributes (such
as configuration parameters or behaviors), and is equally applicable
to the active and passive modes of a stateful PCE and a stateless
PCE.
2. Terminology
This document uses the following terms defined in [RFC5440]: PCC,
PCE, PCEP Peer.
The following term is defined in this document:
Association Timeout Interval: when a PCEP session is terminated, a
PCC waits for this time period before deleting associations created
by the PCEP peer.
3. Architectural Overview
3.1. Motivation
Stateful PCE provides the ability to update existing LSPs and to
instantiate new ones. To enable support for PCE-controlled make-
before-break and for protection, there is a need to define
associations between LSPs. For example, the association between the
original and the re-optimized path in the make-before break scenario,
or between the working and protection path in end-to-end protection.
Another use for LSP grouping is for applying a common set of
configuration parameters or behaviors to a set of LSPs.
For a stateless PCE, it might be useful to associate a path
computation request to an association group, thus enabling it to
associate a common set of configuration parameters or behaviors with
the request.
Rather than creating separate mechanisms for each use case, this
draft defines a generic mechanism that can be reused as needed.
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3.2. Operation Overview
LSPs are associated with other LSPs with which they interact by
adding them to a common association group. Association groups as
defined in this document can be applied to LSPs originating at the
same head end or different head ends. For LSPs originating at the
same head end, the association can be initiated by either the PCC
(head end) or by a PCE. Only a stateful PCE can initiate an
association for LSPs originating at different head ends. For both
cases, the association is uniquely identified by the combination of
an association identifier and the address of the node that created
the association.
Multiple types of groups can exist, each with their own identifiers
space. The definition of the different association types and their
behaviors is outside the scope of this document. The establishment
and removal of the association relationship can be done on a per LSP
basis. An LSP may join multiple association groups, of different or
of the same type.
In the case of a stateless PCE, associations are created out of band,
and PCEP peers should be aware of the association and its
significance outside of the protocol.
Association groups can be created by both PCC and PCE. When a PCC's
PCEP session with a PCE terminates unexpectedly, the PCC cleans up
associations (as per the processing rules in this document).
4. ASSOCIATION Object
4.1. Object Definition
Creation of an association group and modifications to its membership
can be initiated by either the PCE or the PCC. Association groups
and their memberships are defined using the ASSOCIATION object for
stateful PCE.
ASSOCIATION Object-Class is to be assigned by IANA (TBD).
ASSOCIATION Object-Type is 1 for IPv4 and its format is shown in
Figure 1:
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | Flags |R|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Association type | Association ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 Association Source |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Optional TLVs //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: The IPv4 ASSOCIATION Object format
ASSOCIATION Object-Type is 2 for IPv6 and its format is shown in
Figure 2:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | Flags |R|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Association type | Association ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| IPv6 Association Source |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Optional TLVs //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: The IPv6 ASSOCIATION Object format
Reserved: 16 bits - MUST be set to 0 and ignored upon receipt.
Flags: 16 bits - The following flags are currently defined:
R (Removal - 1 bit): when set, the requesting PCE peer requires the
removal of an LSP from the association group.
Association type: 16 bits - the association type (for example
protection). The association type will be defined in separate
documents.
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Association ID: 16 bits - the identifier of the association group.
When combined with Type and Association Source, this value uniquely
identifies an association group. The value 0xffff and 0x0 are
reserved. The value 0xffff is used to indicate all association
groups.
Association Source: 4 or 16 bytes - An IPv4 or IPv6 address, which is
associated to the node that originated the association.
Optional TLVs: The optional TLVs follow the PCEP TLV format of
[RFC5440]. This document defines two optional TLVs.
4.1.1. Global Association Source TLV
The Global Association Source TLV is an optional TLV for use in the
Association 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Global Association Source |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: The Global Association Source TLV format
Type: To be allocated by IANA
Length: Fixed value of 4 bytes
Global Association Source: as defined in [RFC6780]
4.1.2. Extended Association ID TLV
The Extended Association ID TLV is an optional TLV for use in the
Association Object.
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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 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Extended Association ID //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: The Extended Association ID TLV format
Type: To be allocated by IANA
Length: variable
Extended Association ID: as defined in [RFC6780]
4.2. Object Encoding in PCEP messages
The ASSOCIATION Object is OPTIONAL and MAY be carried in the Path
Computation Update (PCUpd), Path Computation Report (PCRpt) and Path
Computation Initiate (PCinit) messages.
When carried in PCRpt message, it is used to report the association
group membership information pertaining to a LSP to a stateful PCE.
It can also be used to remove an LSP from one or more association
groups by setting the R flag to 1. Unless, a PCE wants to delete an
association from an LSP, it does not need to carry the ASSOCIATION
object while updating other LSP attributes using the PCUpd message.
The PCRpt message is defined in [I-D.ietf-pce-stateful-pce] and
updated as below:
<PCRpt Message> ::= <Common Header>
<state-report-list>
Where:
<state-report-list> ::= <state-report>[<state-report-list>]
<state-report> ::= [<SRP>]
<LSP>
[<association-list>]
<path>
Where:
<association-list> ::= <ASSOCIATION> [<association-list>]
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When an LSP is delegated to a stateful PCE, the stateful PCE can
initiate a new association group for this LSP, or associate it with
one or more existing association groups. This is done by including
the ASSOCIATION Object in a PCUpd message or in a PCInit message. A
stateful PCE can also remove a delegated LSP from one or more
association groups by setting the R flag to 1.
The PCUpd message is defined in [I-D.ietf-pce-stateful-pce] and
updated as below:
<PCUpd Message> ::= <Common Header>
<update-request-list>
Where:
<update-request-list> ::= <update-request>[<update-request-list>]
<update-request> ::= <SRP>
<LSP>
[<association-list>]
<path>
Where: <association-list> ::= <ASSOCIATION> [<association-list>]
The PCInitiate message is defined in [I-D.ietf-pce-pce-initiated-lsp]
and updated as below:
<PCInitiate Message> ::= <Common Header>
<PCE-initiated-lsp-list>
Where:
<PCE-initiated-lsp-list> ::=
<PCE-initiated-lsp-request>[<PCE-initiated-lsp-list>]
<PCE-initiated-lsp-request>::=
(<PCE-initiated-lsp-instantiation>|<PCE-initiated-lsp-deletion>)
<PCE-initiated-lsp-instantiation> ::= <SRP>
<LSP>
<END-POINTS>
<ERO>
[<association-list>]
[<attribute-list>]
Where:
<association-list> ::= <ASSOCIATION> [<association-list>]
In case of passive stateful or stateless PCE, the ASSOCIATION Object
is OPTIONAL and MAY be carried in the Path Computation Request
(PCReq) message.
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When carried in a PCReq message, the ASSOCIATION Object is used to
associate the path computation request to an association group, the
association might be further informed via PCRpt message in case of
passive stateful PCE later or it might be created out of band in case
of stateless PCE.
The PCReq message is defined in [RFC5440] and updated in [I-D.ietf-
pce-stateful-pce], it is further updated below for association:
<PCReq Message>::= <Common Header>
[<svec-list>]
<request-list>
Where:
<svec-list>::= <SVEC>[<svec-list>]
<request-list>::= <request>[<request-list>]
<request>::= <RP>
<END-POINTS>
[<LSP>]
[<LSPA>]
[<BANDWIDTH>]
[<metric-list>]
[<association-list>]
[<RRO>[<BANDWIDTH>]]
[<IRO>]
[<LOAD-BALANCING>]
Where:
<association-list> ::= <ASSOCIATION> [<association-list>]
Note that LSP object MAY be present for the passive stateful PCE.
4.3. Processing Rules
Both a PCC and a PCE can create one or more association groups for an
LSP. But a PCE peer cannot add new members for association group
created by another peer. If a PCE peer does not recognize the
ASSOCIATION object, it MUST return a PCErr message with Error-Type
"Unknown Object" as described in [RFC5440]. If a PCE peer is
unwilling or unable to process the ASSOCIATION object, it MUST return
a PCErr message with the Error-Type "Not supported object" and follow
the relevant procedures described in [RFC5440].
The association timeout interval is as a PCC-local value that can be
operator-configured or computed by the PCC based on local policy and
is used in the context of cleaning up associations on session
failure. The association timeout must be set to a value no larger
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than the state timeout interval (defined in
[I-D.ietf-pce-stateful-pce]) and larger than the delegation timeout
interval (defined in [I-D.ietf-pce-stateful-pce].
When a PCC's PCEP session wih the PCE terminates unexpectedly, the
PCC MUST wait for the association timeout interval before cleaning up
the association. If this PCEP session can be re-established before
the association timeout interval time expires, no action is taken to
clean the association created by this PCE. During the time window of
the redelegation timeout interval and the association timeout
interval, the PCE, after re-establishing the session, can also ask
for redelegation following the procedure defined in
[I-D.ietf-pce-stateful-pce] and [I-D.ietf-pce-pce-initiated-lsp].
When the association timeout interval timers expires, the PCC clears
all the associations which are not delegated to any PCEs.
Upon LSP delegation revocation, the PCC MAY clear the association
created by the related PCE, but in order to avoid traffic loss, it
can perform this in a make-before-break fashion, which is the same as
what is defined in Stateful pce [I-D.ietf-pce-stateful-pce] for
handling LSP state cleanup.
Error handling for situations for multiple PCE scenarios will be
included in future versions of this draft.
5. IANA Considerations
The "PCEP Parameters" registry contains a subregistry "PCEP Objects".
This document request IANA to allocate the values from this registry.
Object-Class Value Name Reference
TBD Association This document
Object-Type
1: IPv4
2: IPv6
This document defines the following new PCEP TLVs:
Value Meaning Reference
TBD Global Association Source This document
TBD Extended Association Id This document
This document requests IANA to create a subregistry of the "PCEP
Parameters" for the bits carried in the Flags field of the
ASSOCIATION object. The subregistry is called "ASSOCIATION Flags
Field".
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The field contains 12 bits numbered from bit 0 as the most
significant bit.
Bit; Name: Description Reference
15 R: Removal This document
6. Security Considerations
The security considerations described in [I-D.ietf-pce-stateful-pce]
apply to the extensions described in this document. Additional
considerations related to a malicious PCE are introduced, as the PCE
may now create additional state on the PCC through the creation of
association groups.
7. Acknowledgements
We would like to thank Yuji Kamite and Joshua George for their
contributions to this document. Also Thank Venugopal Reddy and Cyril
Margaria for their useful comments.
8. Contributors
Dhruv Dhody
Huawei Technologies
Divyashree Techno Park, Whitefield
Bangalore, Karnataka 560037
India
Email: dhruv.ietf@gmail.com
9. References
9.1. Normative References
[I-D.ietf-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-ietf-pce-pce-initiated-lsp-05 (work in
progress), October 2015.
[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.
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[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>.
[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>.
[RFC6780] Berger, L., Le Faucheur, F., and A. Narayanan, "RSVP
ASSOCIATION Object Extensions", RFC 6780,
DOI 10.17487/RFC6780, October 2012,
<http://www.rfc-editor.org/info/rfc6780>.
9.2. Informative References
[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>.
Authors' Addresses
Ina Minei
Google, Inc.
1600 Amphitheatre Parkway
Mountain View, CA 94043
US
Email: inaminei@google.com
Edward Crabbe
Email: edward.crabbe@gmail.com
Siva Sivabalan
Cisco Systems, Inc.
170 West Tasman Dr.
San Jose, CA 95134
US
Email: msiva@cisco.com
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Hariharan Ananthakrishnan
Packet Design
Email: hari@packetdesign.com
Xian Zhang
Huawei Technologies
F3-5-B R&D Center, Huawei Base Bantian, Longgang District
Shenzhen, Guangdong 518129
P.R.China
Email: zhang.xian@huawei.com
Yosuke Tanaka
NTT Communications Corporation
Granpark Tower 3-4-1 Shibaura, Minato-ku
Tokyo 108-8118
Japan
Email: yosuke.tanaka@ntt.com
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