PCEP Extension for TE Constraints
draft-peng-pce-te-constraints-00
The information below is for an old version of the document.
| Document | Type |
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|---|---|---|---|
| Authors | Shaofu Peng , Quan Xiong | ||
| Last updated | 2019-07-30 | ||
| Replaced by | draft-xpbs-pce-topology-filter, draft-xiong-pce-nrp-id, draft-xpbs-pce-topology-filter | ||
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draft-peng-pce-te-constraints-00
PCE S. Peng
Internet-Draft Q. Xiong
Intended status: Standards Track ZTE Corporation
Expires: January 30, 2020 July 29, 2019
PCEP Extension for TE Constraints
draft-peng-pce-te-constraints-00
Abstract
This document proposes a set of constraints for PCEP to configure PCE
to use specific virtual network topology or application attributes
during path computation. A simple COLOR parameter is also introduced
to simplify network operations.
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 January 30, 2020.
Copyright Notice
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document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions used in this document . . . . . . . . . . . . . . 3
2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2.2. Requirements Language . . . . . . . . . . . . . . . . . . 3
3. PCEP Extensions for Constraints . . . . . . . . . . . . . . . 3
3.1. Source Protocol Object . . . . . . . . . . . . . . . . . 3
3.2. Multi-topology Object . . . . . . . . . . . . . . . . . . 4
3.3. The AII Object . . . . . . . . . . . . . . . . . . . . . 5
3.4. Application Specific Object . . . . . . . . . . . . . . . 6
3.5. The Color Object . . . . . . . . . . . . . . . . . . . . 7
4. Security Considerations . . . . . . . . . . . . . . . . . . . 8
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
7. Normative References . . . . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction
[RFC5440] describes the Path Computation Element Protocol (PCEP)
which is used between a Path Computation Element (PCE) and a Path
Computation Client (PCC) (or other PCE) to enable computation of
Multi-protocol Label Switching (MPLS) for Traffic Engineering Label
Switched Path (TE LSP). PCEP Extensions for the Stateful PCE Model
[RFC8231] describes a set of extensions to PCEP to enable active
control of MPLS-TE and Generalized MPLS (GMPLS) tunnels. [RFC8281]
describes the setup and teardown of PCE-initiated LSPs under the
active stateful PCE model, without the need for local configuration
on the PCC, thus allowing for dynamic centralized control of a
network.
Till now there are known path computation constraint parameters such
as metric, bandwidth, delay, affinity, etc. However all these
parameters can't meet increasing service requirements. A PCE always
perform path computation based on the network topology information
collected through BGP-LS [RFC7752]. BGP-LS can get multiple link-
state database from multiple IGP instance, or multiple virtual
topology from a single IGP instance. It is necessary to limit PCE to
a small topology scope during path computation for some special
purpose. BGP-LS can also get application specific TE attributes for
a link, it is also necessary to limit PCE to use TE attributes of
specific application during path computation.
This document will extend PCEP to support some new constraint
parameters during path computation, e.g, IGP instance, virtual
network, specific application, as well as a simple COLOR parameter.
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2. Conventions used in this document
2.1. Terminology
The terminology is defined as [RFC5440] and [RFC7752].
2.2. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
3. PCEP Extensions for Constraints
3.1. Source Protocol Object
The Source Protocol object is optional and can be used for several
purposes.
In a PCReq message, a PCC MAY insert one Source Protocol object to
indicate the source protocol that MUST be considered by the PCE, The
later will perform path computation based on the sub-topology
identified by the specific source protocol. The absence of the
Source Protocol object MUST be interpreted by the PCE as a path
computation request for which no constraints need be applied to any
of the source protocols.
In a PCRep/PCInit/PCUpd message, the Source Protocol object MAY be
inserted so as to provide the source protocol information for the
computed path.
Only one Source Protocol Object could be inserted in the above
messages, otherwise the first one MUST be considered and others MUST
be ignored.
Source Protocol Object-Class is TBA.
Source Protocol Object-Type is 1.
The format of the Source Protocol object is shown as 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Protocol-ID | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Identifier |
| (64 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Source Protocol Object
The Source Protocol object body has a fixed length of 12 bytes.
Protocol-ID (8 bits): defined in [RFC7752] section 3.2.
Reserved (24 bits): This field MUST be set to zero on transmission
and MUST be ignored on receipt.
Identifier (64 bits): defined in [RFC7752] section 3.2.
3.2. Multi-topology Object
The Multi-topology object is optional and can be used for several
purposes.
In a PCReq message, a PCC MAY insert one Multi-topology object to
indicate the sub-topology of an IGP instance that MUST be considered
by the PCE, The later will perform path computation based on the sub-
topology identified by the specific Multi-Topology ID within a source
protocol. The absence of the Multi-topology object MUST be
interpreted by the PCE as a path computation request for which no
constraints need be applied to any of the multi-topologies.
In a PCRep/PCInit/PCUpd message, the Multi-topology object MAY be
inserted so as to provide the Multi-topology information for the
computed path.
Only one Multi-topology Object could be inserted in the above
messages, otherwise the first one MUST be considered and others MUST
be ignored. It MUST be inserted with a Source Protocol Object, if
not it MUST be ignored.
Multi-topology Object-Class is TBA.
Multi-topology Object-Type is 1.
The format of the Multi-topology object is shown as Figure 2:
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|R R R R| Multi-Topology ID | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Multi-topology Object
The Multi-topology object body has a fixed length of 4 bytes.
Multi-Topology ID (16 bits): Semantics of the IS-IS MT-ID are defined
in Section 7.2 of [RFC5120]. Semantics of the OSPF MT-ID are defined
in Section 3.7 of [RFC4915]. If the value is derived from OSPF, then
the upper 9 bits MUST be set to 0. Bits R are reserved and SHOULD be
set to 0 when originated and ignored on receipt.
Reserved (16 bits): This field MUST be set to zero on transmission
and MUST be ignored on receipt.
3.3. The AII Object
The AII object is optional and can be used for several purposes.
In a PCReq message, a PCC MAY insert one AII object to indicate the
global virtual network that MUST be considered by the PCE, The later
will perform path computation based on the intra or inter-domain sub-
topology identified by the specific AII, which is independent of
routing protocols such as IGP/BGP. The absence of the AII object
MUST be interpreted by the PCE as a path computation request for
which no constraints need be applied to any of the virtual network,
i.e, a default AII (0) will be applied.
In a PCRep/PCInit/PCUpd message, the AII object MAY be inserted so as
to provide the network slicing information for the computed path.
Only one AII Object could be inserted in the above messages,
otherwise the first one MUST be considered and others MUST be
ignored.
AII Object-Class is TBA.
AII Object-Type is 1.
The format of the AII object is shown as Figure 3:
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AII |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: AII Object
The AII object body has a fixed length of 4 bytes.
AII (32 bits): Administrative Instance Identifier defined in
[I-D.peng-lsr-network-slicing].
3.4. Application Specific Object
The Application Specific object is optional and can be used for
several purposes.
In a PCReq message, a PCC MAY insert one Application Specific object
to indicate the appliaction that MUST be considered by the PCE, The
later will perform path computation using the specific application
attributes. The absence of the Application Specific object MUST be
interpreted by the PCE as a path computation request for which no
constraints need be applied to any of the Application Specific
attributes.
In a PCRep/PCInit/PCUpd message, the Application Specific object MAY
be inserted so as to provide the Application Specific information for
the computed path.
Only one Application Specific Object could be inserted in the above
messages, otherwise the first one MUST be considered and others MUST
be ignored.
Application Specific Object-Class is TBA.
Application Specific Object-Type is 1.
The format of the Application Specific object is shown as Figure 4:
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Standard Application ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| User Defined Application ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: Application Specific Object
The Application Specific object body has a fixed length of 8 bytes.
Standard Application ID : Represents a bit-position value for a
single STANDARD application that is defined in the IANA "IGP
Parameters" registries under the "Link Attribute Applications"
registry [I-D.ietf-isis-te-app].
User Defined Application ID : Represents a single user defined
application that is implementation specific.
3.5. The Color Object
The Color object is optional and can be used for several purposes.
In a PCReq message, a PCC MAY insert one Color object to indicate the
traffic engineering purpose that is recognized by the both PCE and
PCC with no conflict meaning. The later will perform path
computation based on the color template defined in local and extract
the detailed constraints from the color template. Note the same
color template is also defined in PCC side. At this time, any other
traditional constraints (i.e, metric, bandwidth, dealy, etc) that is
directly contained in the message MUST be ignored. The absence of
the Color object MUST be interpreted by the PCE as a path computation
request for which traditional constraints that are contained in
message need be applied.
In a PCRep/PCInit/PCUpd message, the Color object MAY be inserted so
as to provide the TE purpose information for the computed path, the
PCC recognize the color value that match a local color-template.
Only one Color Object could be inserted in the above messages,
otherwise the first one MUST be considered and others MUST be
ignored.
Color Object-Class is TBA.
Color Object-Type is 1.
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The format of the Color object is shown as Figure 5:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Color |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: Color Object
The Color object body has a fixed length of 4 bytes.
Color (32 bits): Represent a TE purpose, 0 is invalid value. It is
consistent with the meaning of Color Extended Community that is
defined in [I-D.ietf-idr-tunnel-encaps], and color of SR policy that
is also defined in [I-D.ietf-spring-segment-routing-policy].
Note that Color Object defined in this document is used to represent
a TE purpose, it can be suitable for any TE instance such as RSVP-TE,
SR-TE, SR-policy. [I-D.barth-pce-segment-routing-policy-cp] has
already been using SR policy KEY (that also includes a color
information) as an association group KEY to associate many candidate
paths, however it is only for association purpose but not constraint
purpose for path computation.
A color tempate can be defined to use any constraints such as
traditional metric, bandwidth, dealy, affinity parameters, but also
any sub-topology parameters above defined in this document. Both PCE
and PCC MUST have the same understanding for a same color value.
4. Security Considerations
TBA
5. Acknowledgements
TBA
6. IANA Considerations
IANA is requested to make allocations from the registry, as follows:
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+--------+------------------------------+------------------+
| Value | Object | Reference |
+--------+------------------------------+------------------+
| TBA1 | Source Protocol Object | [this document] |
| TBA2 | Multi-topology Object | [this document] |
| TBA3 | AII Object | [this document] |
| TBA4 | Application Specific Object | [this document] |
| TBA5 | Color Object | [this document] |
+--------+------------------------------+------------------+
Table 1
7. Normative References
[I-D.barth-pce-segment-routing-policy-cp]
Koldychev, M., Sivabalan, S., Barth, C., and C. Li, "PCEP
extension to support Segment Routing Policy Candidate
Paths", draft-barth-pce-segment-routing-policy-cp-03 (work
in progress), July 2019.
[I-D.ietf-idr-tunnel-encaps]
Patel, K., Velde, G., Ramachandra, S., and E. Rosen, "The
BGP Tunnel Encapsulation Attribute", draft-ietf-idr-
tunnel-encaps-13 (work in progress), July 2019.
[I-D.ietf-isis-te-app]
Ginsberg, L., Psenak, P., Previdi, S., Henderickx, W., and
J. Drake, "IS-IS TE Attributes per application", draft-
ietf-isis-te-app-06 (work in progress), April 2019.
[I-D.ietf-spring-segment-routing-policy]
Filsfils, C., Sivabalan, S., daniel.voyer@bell.ca, d.,
bogdanov@google.com, b., and P. Mattes, "Segment Routing
Policy Architecture", draft-ietf-spring-segment-routing-
policy-03 (work in progress), May 2019.
[I-D.peng-lsr-network-slicing]
Peng, S., Chen, R., and G. Mirsky, "Packet Network Slicing
using Segment Routing", draft-peng-lsr-network-slicing-00
(work in progress), February 2019.
[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>.
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[RFC4915] Psenak, P., Mirtorabi, S., Roy, A., Nguyen, L., and P.
Pillay-Esnault, "Multi-Topology (MT) Routing in OSPF",
RFC 4915, DOI 10.17487/RFC4915, June 2007,
<https://www.rfc-editor.org/info/rfc4915>.
[RFC5120] Przygienda, T., Shen, N., and N. Sheth, "M-ISIS: Multi
Topology (MT) Routing in Intermediate System to
Intermediate Systems (IS-ISs)", RFC 5120,
DOI 10.17487/RFC5120, February 2008,
<https://www.rfc-editor.org/info/rfc5120>.
[RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
Element (PCE) Communication Protocol (PCEP)", RFC 5440,
DOI 10.17487/RFC5440, March 2009,
<https://www.rfc-editor.org/info/rfc5440>.
[RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and
S. Ray, "North-Bound Distribution of Link-State and
Traffic Engineering (TE) Information Using BGP", RFC 7752,
DOI 10.17487/RFC7752, March 2016,
<https://www.rfc-editor.org/info/rfc7752>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8231] Crabbe, E., Minei, I., Medved, J., and R. Varga, "Path
Computation Element Communication Protocol (PCEP)
Extensions for Stateful PCE", RFC 8231,
DOI 10.17487/RFC8231, September 2017,
<https://www.rfc-editor.org/info/rfc8231>.
[RFC8281] Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "Path
Computation Element Communication Protocol (PCEP)
Extensions for PCE-Initiated LSP Setup in a Stateful PCE
Model", RFC 8281, DOI 10.17487/RFC8281, December 2017,
<https://www.rfc-editor.org/info/rfc8281>.
Authors' Addresses
Shaofu Peng
ZTE Corporation
No.50 Software Avenue
Nanjing, Jiangsu 210012
China
Email: peng.shaofu@zte.com.cn
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Quan Xiong
ZTE Corporation
No.6 Huashi Park Rd
Wuhan, Hubei 430223
China
Email: xiong.quan@zte.com.cn
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