PCE Working Group Y. Lee
Internet-Draft D. Dhody
Intended Status: Standards track X. Zhang
Expires: September 14, 2017 Huawei Technologies
D. Ceccarelli
Ericsson
March 13, 2017
PCEP Extensions for Establishing Relationships Between Sets of LSPs
and Virtual Networks
draft-leedhody-pce-vn-association-02
Abstract
This document describes how to extend Path Computation Element (PCE)
Communication Protocol (PCEP) association mechanism introduced by the
PCEP Association Group specification, to further associate sets of
LSPs with a higher-level structure such as a virtual network (VN)
requested by clients or applications. This extended association
mechanism can be used to facilitate virtual network control using PCE
architecture.
Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79.
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material or to cite them other than as "work in progress."
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Table of Contents
1. Introduction...................................................2
1.1. Requirements Language.....................................3
2. Terminology....................................................4
3. Operation Overview.............................................4
4. Extensions to PCEP.............................................4
5. Applicability to H-PCE architecture............................6
6. Security Considerations........................................7
7. IANA Considerations............................................7
7.1. Association Object Type Indicator.........................7
7.2. PCEP TLV Type Indicator...................................8
7.3. PCEP Error................................................8
8. References.....................................................8
8.1. Normative References......................................8
8.2. Informative References....................................9
Author's Addresses................................................9
1. Introduction
The Path Computation Element communication Protocol (PCEP) provides
mechanisms for Path Computation Elements (PCEs) to perform path
computations in response to Path Computation Clients' (PCCs)
requests.
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[RFC8051] describes general considerations for a stateful PCE
deployment and examines its applicability and benefits, as well as
its challenges and limitations through a number of use cases.
[I-D.ietf-pce-stateful-pce] describes a set of extensions to PCEP to
provide stateful control. A stateful PCE has access to not only the
information carried by the network's Interior Gateway Protocol (IGP),
but also the set of active paths and their reserved resources for its
computations. The additional state allows the PCE to compute
constrained paths while considering individual LSPs and their
interactions.
[I-D.ietf-pce-pce-initiated-lsp] describes the setup, maintenance and
teardown of PCE-initiated LSPs under the stateful PCE model.
[I-D.ietf-pce-association-group] introduces a generic mechanism to
create a grouping of LSPs. This grouping can then be used to define
association between sets of LSPs or between a set of LSPs and a set
of attributes.
[ACTN-REQ] describes various Virtual Network (VN) operations
initiated by a customer/application. In this context, there is a need
for associating a set of LSPs with a VN "construct" to facilitate VN
operations in PCE architecture. This association allows the PCEs to
identify which LSPs belong to a certain VN. The PCE could then use
this association to optimize all LSPs belonging to the VN together.
The PCE could further take VN specific actions on the LSPs such as
relaxation of constraints, policy actions, setting default behavior
etc.
[I-D.dhody-pce-applicability-actn] examines the PCE and ACTN
architecture and describes how the PCE architecture is applicable to
ACTN. [RFC6805] and [I-D.dhodylee-pce-stateful-hpce] describes a
hierarchy of stateful PCEs with Parent PCE coordinating multi-domain
path computation function between Child PCE(s) and thus making it the
base for PCE applicability for ACTN. In this text child PCE would be
same as PNC, and the parent PCE as MDSC[ACTN-FWK].
This document specifies a PCEP extension to associate a set of LSPs
based on Virtual Network (or customer).
1.1. 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].
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2. Terminology
The terminology is as per [RFC4655], [RFC5440], [RFC6805], and [I-
D.ietf-pce-stateful-pce].
3. Operation Overview
As per [I-D.ietf-pce-association-group], LSPs are associated with
other LSPs with which they interact by adding them to a common
association group.
An association group based on VN is useful for various optimizations
that should be applied by considering all the LSPs in the
association. This includes, but not limited to -
o Path Computation: When computing path for a LSP, the impact of
this LSP, on the other LSPs belonging to the same VN is useful to
analyze. The aim would be optimize overall VN and all LSPs, rather
than a single LSP. Also, the optimization criteria such as
minimize the load of the most loaded link (MLL) [RFC5541] and
other could be applied for all the LSP belonging to the same VN,
identified by the VN association.
o Path Re-Optimization: The child PCE or the parent PCE would like
to use advanced path computation algorithm and optimization
technique that consider all the LSPs belonging to a VN/customer
and optimize them all together.
This association is useful in PCEP session between parent PCE
(MDSC) and child PCE (PNC).
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******
..........*MDSC*..............................
. ****** .. MPI .
. . . PCEP .
. . . PCInitiate LSPx .
. . . with VNAG = 10 .
. . . .
. . . .
. . . .
v v v .
****** ****** ****** .
*PNC1* *PNC2* *PNC4* .
****** ****** ****** .
+---------------+ +---------------+ +---------------+ .
|A |----| |----| C| .
| | | | | | .
|DOMAIN 1 |----|DOMAIN 2 |----|DOMAIN 4 | .
+------------B13+ +---------------+ +B43------------+ .
/ .
****** / .
*PNC3*<............/.....................
****** /
+---------------+/
B31 B34
| |
|DOMAIN 3 B|
+---------------+
MDSC -> Parent PCE
PNC -> Child PCE
MPI -> PCEP
In this draft, this grouping is used to define associations between a
set of LSPs and a virtual network.
One new optional Association Object-type is defined based on the
generic Association object -
o VN Association Group (VNAG)
Thus this document define one new association type called "VN
Association Type" of value TBD1. The scope and handling of VNAG
identifier is similar to the generic association identifier defined
in [I-D.ietf-pce-association-group].
Local polices on the PCE MAY define the computational and
optimization behavior for the LSPs in the VN. An LSP MUST belong to a
single VNAG. If an implementation encounters more than one VNAG, it
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MUST consider the first occurrence and ignore the others.
4. Extensions to PCEP
[I-D.ietf-pce-association-group] introduces the ASSOCIATION object,
the format of VNAG is as follows:
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=TBD1 | Association ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 Association Source |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Optional TLVs //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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=TBD1 | Association ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| IPv6 Association Source |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Optional TLVs //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: The VNAG Object formats
Please refer to [I-D.ietf-pce-association-group] for the definition
of each field in Figure 1. This document defines one mandatory TLV
"VIRTUAL-NETWORK-TLV" and one optional TLV "VENDOR-INFORMATION-TLV" -
o VIRTUAL-NETWORK-TLV: Used to communicate the VN Identifier.
o VENDOR-INFORMATION-TLV: Used to communicate arbitrary vendor
specific behavioral information, described in [RFC7470].
The format of VIRTUAL-NETWORK-TLV is as follows.
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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=TBD2 | Length (variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Virtual Network Name //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: The VIRTUAL-NETWORK-TLV formats
Type: TBD2 (to be allocated by IANA)
Length: Variable Length
Virtual Network Name(variable): symbolic name for the VN.
The VIRTUAL-NETWORK-TLV MUST be included in VNAG object.If a PCEP
speaker receives the VNAG object without the VIRTUAL-NETWORK-TLV, it
MUST send a PCErr message with Error-Type= 6 (mandatory object
missing) and Error-Value=TBD3 (VIRTUAL-NETWORK-TLV missing) and close
the session.
The format of VENDOR-INFORMATION-TLV is defined in [RFC7470].
5. Applicability to H-PCE architecture
The ability to compute shortest constrained TE LSPs in Multiprotocol
Label Switching (MPLS) and Generalized MPLS (GMPLS) networks across
multiple domains has been identified as a key motivation for PCE
development. [RFC6805] describes a Hierarchical PCE (H-PCE)
architecture which can be used for computing end-to-end paths for
inter-domain MPLS Traffic Engineering (TE) and GMPLS Label Switched
Paths (LSPs). Within the hierarchical PCE architecture, the parent
PCE is used to compute a multi-domain path based on the domain
connectivity information. A child PCE may be responsible for a
single domain or multiple domains, it is used to compute the intra-
domain path based on its domain topology information.
[I-D.dhodylee-pce-stateful-hpce] introduces general considerations
for stateful PCE(s) in hierarchical PCE architecture. In particular,
the behavior changes and additions to the existing stateful PCE
mechanisms in the context of a H-PCE architecture.
In Stateful H-PCE architecture, the Parent PCE receives a virtual
network creation request by its client over its Northbound API. This
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VN is uniquely identified by an Association ID in VNAG as well as the
VIRTUAL-NETWORK name. This VN may comprise multiple LSPs in the
network in a single domain or across multiple domains.
As the Parent PCE computes the optimum E2E paths for each tunnel in
VN, it MUST associate each LSP with the VN to which it belongs.
Parent PCE sends a PCInitiate Message with this association
information in the VNAG Object (See Section 4 for details). This in
effect binds an LSP that is to be instantiated at the child PCE with
the VN.
Whenever changes occur with the instantiated LSP in a domain network,
the domain child PCE reports the changes using a PCRpt Message in
which the VNAG Object indicates the relationship between the LSP and
the VN.
Whenever an update occurs with VNs in the Parent PCE (via the
client's request), the parent PCE sends an PCUpd Message to inform
each affected child PCE of this change.
The Child PCE could then use this association to optimize all LSPs
belonging to the same VN association together. The Child PCE could
further take VN specific actions on the LSPs such as relaxation of
constraints, policy actions, setting default behavior etc. The parent
PCE could also maintain all E2E LSP or per-domain path segments under
a single VN association.
6. Security Considerations
This document defines one new type for association, which do not add
any new security concerns beyond those discussed in [RFC5440], [I-
D.ietf-pce-stateful-pce] and [I-D.ietf-pce-association-group] in
itself.
Some deployments may find VN associations and their implications as
extra sensitive and thus should employ suitable PCEP security
mechanisms like TCP-AO or [I-D.ietf-pce-pceps].
7. IANA Considerations
7.1. Association Object Type Indicator
This document defines the following new association type originally
defined in [I-D.ietf-pce-association-group].
Value Name Reference
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TBD1 VN Association Type [This I.D.]
7.2. PCEP TLV Type Indicator
This document defines the following new PCEP TLV; IANA is requested
to make the following allocations from this registry at
<http://www.iana.org/assignments/pcep/>; see PCEP TLV Type
Indicators.
Value Name Reference
TBD2 VIRTUAL-NETWORK-TLV [This I.D.]
7.3. PCEP Error
IANA is requested to make the following allocations from this
registry at <http://www.iana.org/assignments/pcep/>; see PCEP-ERROR
Object Error Types and Values.
This document defines new Error-Type and Error-Value for the
following new error conditions:
Error-Type Meaning
6 Mandatory Object missing
Error-value=TBD3: VIRTUAL-NETWORK TLV missing
8. Manageability Considerations
8.1. Control of Function and Policy
An operator MUST BE allowed to mark LSPs that belong to the same VN.
This could also be done automatically based on the VN configuration.
8.2. Information and Data Models
The PCEP YANG module [I-D.ietf-pce-pcep-yang] should support the
association between LSPs including VN association.
8.3. Liveness Detection and Monitoring
Mechanisms defined in this document do not imply any new liveness
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detection and monitoring requirements in addition to those already
listed in [RFC5440].
8.4. Verify Correct Operations
Mechanisms defined in this document do not imply any new operation
verification requirements in addition to those already listed in
[RFC5440].
8.5. Requirements On Other Protocols
Mechanisms defined in this document do not imply any new requirements
on other protocols.
8.6. Impact On Network Operations
Mechanisms defined in this document do not have any impact on network
operations in addition to those already listed in [RFC5440].
9. References
9.1. 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.
[RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
Element (PCE) Communication Protocol (PCEP)", RFC 5440,
March 2009.
[I-D.ietf-pce-stateful-pce] E. Crabbe, I. Minei, J. Medved, and R.
Varga, "PCEP Extensions for Stateful PCE", draft-ietf-pce-
stateful-pce, work in progress.
[I-D.ietf-pce-pce-initiated-lsp] E. Crabbe, et. al., "PCEP Extensions
for PCE-initiated LSP Setup in a Stateful PCE Model",
draft-ietf-pce-pce-initiated-lsp, work in progress.
[I-D.ietf-pce-association-group] I, Minei, Ed., "PCEP Extensions for
Establishing Relationships Between Sets of LSPs", draft-
ietf-pce-association-group, work in progress.
9.2. Informative References
[RFC4655] Farrel, A., Vasseur, J.-P., and J. Ash, "A Path Computation
Element (PCE)-Based Architecture", RFC 4655, August 2006.
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[RFC6805] A. Farrel and D. King, "The Application of the Path
Computation Element Architecture to the Determination of a
Sequence of Domains in MPLS and GMPLS", RFC 6805, November
2012.
[I-D.dhody-pce-applicability-actn] Dhody D., Lee Y., and D.
Ceccarelli, "Applicability of Path Computation Element
(PCE) for Abstraction and Control of TE Networks (ACTN)",
draft-dhody-pce-applicability-actn, work-in-progress.
[I-D.dhodylee-pce-stateful-hpce] Dhody, D. and Lee, Y., "Hierarchical
Stateful Path Computation Element (PCE)",
draft-dhodylee-pce-stateful-hpce, work in progress.
[ACTN-REQ] Y. Lee, D. Dhody, S. Belotti, K. Pithewan, and D.
Ceccarelli, "Requirements for Abstraction and Control of TE
Networks", draft-ietf-teas-actn-requirements, work in
progress.
[ACTN-FWK] Ceccarelli D. and Y. Lee, "Framework for Abstraction and
Control of Transport Networks", draft-ietf-teas-
actn-framework-04 (work in progress), February 2017.
[RFC5541] Le Roux, JL., Vasseur, JP., and Y. Lee, "Encoding of
Objective Functions in the Path Computation Element
Communication Protocol (PCEP)", RFC 5541,
DOI 10.17487/RFC5541, June 2009,
<http://www.rfc-editor.org/info/rfc5541>.
[RFC7470] Zhang, F. and A. Farrel, "Conveying Vendor-Specific
Constraints in the Path Computation Element Communication
Protocol", RFC 7470, DOI 10.17487/RFC7470, March 2015,
<http://www.rfc-editor.org/info/rfc7470>.
[RFC8051] Zhang, X., Ed. and I. Minei, Ed., "Applicability of a
Stateful Path Computation Element (PCE)", RFC 8051,
DOI 10.17487/RFC8051, January 2017,
<http://www.rfc-editor.org/info/rfc8051>.
[I-D.ietf-pce-pceps]
Lopez, D., Dios, O., Wu, W., and D. Dhody, "Secure
Transport for PCEP", draft-ietf-pce-pceps-11 (work in
progress), January 2017.
[I-D.ietf-pce-pcep-yang]
Dhody, D., Hardwick, J., Beeram, V., and j.
jefftant@gmail.com, "A YANG Data Model for Path
Computation Element Communications Protocol (PCEP)",
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draft-ietf-pce-pcep-yang-02 (work in progress), March
2017.
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Author's Addresses
Young Lee (Editor)
Huawei Technologies
5340 Legacy Drive, Building 3
Plano, TX 75023,
USA
Email: leeyoung@huawei.com
Dhruv Dhody (Editor)
Huawei Technologies
Divyashree Technopark, Whitefield
Bangalore, Karnataka 560066
India
Email: dhruv.ietf@gmail.com
Xian Zhang
Huawei Technologies
China
Email: zhang.xian@huawei.com
Daniele Ceccarelli
Ericsson
Torshamnsgatan,48
Stockholm,
Sweden
Email: daniele.ceccarelli@ericsson.com
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