PCEP Extensions for Topology Filter
draft-xpbs-pce-topology-filter-00
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| Document | Type |
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|---|---|---|---|
| Authors | Quan Xiong , Shaofu Peng , Vishnu Pavan Beeram , Tarek Saad , Mike Koldychev | ||
| Last updated | 2021-10-08 | ||
| Replaced by | draft-ietf-pce-topology-filter | ||
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draft-xpbs-pce-topology-filter-00
PCE Q. Xiong
Internet-Draft S. Peng
Intended status: Standards Track ZTE Corporation
Expires: 11 April 2022 V. Beeram
T. Saad
Juniper Networks
M. Koldychev
Cisco Systems
8 October 2021
PCEP Extensions for Topology Filter
draft-xpbs-pce-topology-filter-00
Abstract
This document proposes a set of extensions for PCEP to support the
topology filter during path computation.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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Task Force (IETF). Note that other groups may also distribute
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and may be updated, replaced, or obsoleted by other documents at any
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on 11 April 2022.
Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved.
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This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
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provided without warranty as described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Topology Filter . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Topology Reference . . . . . . . . . . . . . . . . . . . 4
2.2. Filters . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. PCEP Extensions . . . . . . . . . . . . . . . . . . . . . . . 4
3.1. TOPOLOGY Object . . . . . . . . . . . . . . . . . . . . . 4
3.1.1. Source Protocol TLV . . . . . . . . . . . . . . . . . 5
3.1.2. Multi-topology TLV . . . . . . . . . . . . . . . . . 6
3.1.3. Area TLV . . . . . . . . . . . . . . . . . . . . . . 6
3.1.4. Algorithm TLV . . . . . . . . . . . . . . . . . . . . 7
3.2. IRO Object . . . . . . . . . . . . . . . . . . . . . . . 7
3.2.1. Link ID . . . . . . . . . . . . . . . . . . . . . . . 7
3.2.2. Admin Group . . . . . . . . . . . . . . . . . . . . . 8
3.2.3. Source Protocol . . . . . . . . . . . . . . . . . . . 8
3.3. XRO Object . . . . . . . . . . . . . . . . . . . . . . . 9
3.3.1. Link ID . . . . . . . . . . . . . . . . . . . . . . . 9
3.3.2. Admin Group . . . . . . . . . . . . . . . . . . . . . 9
3.3.3. Source Protocol . . . . . . . . . . . . . . . . . . . 10
3.4. Procedures . . . . . . . . . . . . . . . . . . . . . . . 11
4. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 11
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
5.1. TOPOLOGY Object . . . . . . . . . . . . . . . . . . . . . 11
5.2. IRO Object . . . . . . . . . . . . . . . . . . . . . . . 11
5.3. XRO Object . . . . . . . . . . . . . . . . . . . . . . . 12
6. Security Considerations . . . . . . . . . . . . . . . . . . . 12
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
7.1. Normative References . . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13
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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. As depicted
in [RFC4655], a PCE MUST be able to compute the path of a TE LSP by
operating on the TED and considering bandwidth and other constraints
applicable to the TE LSP service request.
A PCE always perform path computation based on the network topology
information collected through BGP-LS [RFC7752]. BGP-LS can get
multiple link-state data from multiple IGP instance, or multiple
virtual topologies from a single IGP instance. It is necessary to
restrict the PCE to a sub-topology during path computation. The PCE
MUST take the topology constraint into consideration during path
computation.
The sub-topology may be considered as a TE topology or a specific IGP
domain. As defined in draft-bestbar-teas-yang-topology-filter, a
topology filter is a data construct that can be applied on either a
native topology or a user specified topology. The topology filter
can be viewed as a set of filtering rules to construct the sub-
topology. The topology filter specifies the topology reference or a
set of include-any, include-all and exclude filtering rules.
This document proposes a set of extensions for PCEP to support the
topology filter during path computation.
1.1. Terminology
The terminology is defined as [RFC5440], [RFC7752] and [RFC8795].
1.2. 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 RFC 2119 [RFC2119].
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2. Topology Filter
As defined in draft-bestbar-teas-yang-topology-filter, a topology
filter is a data construct that can be applied on either a native
topology or a user specified topology. The topology filter can be
viewed as a set of filtering rules to construct the sub-topology.
The topology filter specifies the topology reference or a set of
include-any, include-all and exclude filtering rules.
2.1. Topology Reference
The topology reference indicates the topology on which the existing
referenced filtering rules need to be applied. The referenced
topology could be a predefined TE topology or a specific IGP domain.
As defined in RFC7752, the IGP domain has a unique IGP representation
by using the combination of Area-ID, Router-ID, Protocol-ID, Multi-
Topology ID, and Instance-ID. This document defines TOPOLOGY object
and new TLVs for the topology filiter such as Source Protocol TLV,
Multi-Topology ID, Area-ID and Algorithm TLV.
2.2. Filters
The topology filters carries a list of filters. Each filter
specifies a set of include-any, include-all and exclude filtering
rules that can be applied on the native topology. The filtering
rules specify the a set of constraints on the topology, that are to
be used to compute path at PCE. This document proposes a set of
extensions for IRO and XRO objext and defines new subobjects such as
Link ID, Link affinity and Source Protocol.
3. PCEP Extensions
3.1. TOPOLOGY Object
This document defines a new TOPOLOGY object to carry the topology
filter.
The TOPOLOGY object is optional and specifies the sub-topology to be
taken into account by the PCE during path computation. The TOPOLOGY
object can be carried within a PCReq message, or a PCRep message in
case of unsuccessful path computation.
TOPOLOGY Object-Class is TBD1.
TOPOLOGY Object-Type is TBD2.
The format of the TOPOLOGY object body is:
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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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Optional TLVs //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: TOPOLOGY Body Object Format
Reserved (24 bits): This field MUST be set to zero on transmission
and MUST be ignored on receipt.
Flags (8 bits): No flags are currently defined. Unassigned flags
MUST be set to zero on transmission and MUST be ignored on receipt.
The format of optional TLVs is defined in RFC5440 and may be used to
carry topology filter information as defined in section.
3.1.1. Source Protocol TLV
The Source Protocol TLV is optional and is defined to carry the
protocol ID and Instance ID.
The format of the Source Protocol TLV is:
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=TBD3 | Length=12 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Protocol-ID | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Instance-ID |
| (64 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Source Protocol TLV
The code point for the TLV type is TBD3. The TLV length is 12
octets.
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Protocol-ID (8 bits): defined in [RFC7752] section 3.2. IS-IS
[RFC8202] and OSPF [RFC6549] MAY run multiple routing protocol
instances identified by the Protocol-ID over the same link.
Reserved (24 bits): This field MUST be set to zero on transmission
and MUST be ignored on receipt.
Instance-ID (64 bits): defined in [RFC7752] section 3.2.
3.1.2. Multi-topology TLV
The Multi-topology TLV is optional and is defined to carry the multi-
topology ID.
The format of the Multi-topology TLV is :
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=TBD4 | Length=4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|R R R R| Multi-Topology ID | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: Multi-topology TLV
The code point for the sub-TLV type is TBD4. The sub-TLV length is 4
octets.
Multi-Topology ID (12 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]. As defined in section 3.2.1.5 of
[RFC7752], 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.
3.1.3. Area TLV
The Area TLV is optional and is defined to carry the Area ID.
The format of the Area TLV is :
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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=TBD5 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Area ID (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: Area TLV
The code point for the TLV type is TBD3. The TLV length is variable.
Area-ID: Area identifier as defined in RFC7752.
3.1.4. Algorithm TLV
The Algorithm TLV is optional and is defined to carry the Algorithm
ID.
The Algorithm TLV MAY be inserted so as to provide the Flex-algo
plane information for the computed path. The format of the TLV is
defined in draft-tokar-pce-sid-algo-04 section 3.4.
3.2. IRO Object
As per [RFC5440], IRO can be used to specify that the computed path
needs to traverse a set of specified network elements or abstract
nodes. This document proposed a set of extensions for topology
filter.
3.2.1. Link ID
The Link ID is used to include the link that is used during the path
calculation.
The Link ID subobject is defined:
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=TBD6 | Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link ID (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: Link ID subobject in IRO
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The code point for the TLV type is TBD6. The TLV length is 12
octets.
Link ID (32bits ): defined in IS-IS RFC5307 and OSPF RFC3630.
3.2.2. Admin Group
The Admin Group is used to include the links that is used during the
path calculation.
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=TBD7 | Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Extended Admin Group |
+- -+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: Admin Group subobject in IRO
The code point for the TLV type is TBD7. The TLV length is variable.
Extended Administrative Group: Extended Administrative Group as
defined in [RFC7308].
3.2.3. Source Protocol
The format of the Source Protocol subobject is:
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=TBD8 | Length | Reserved | Protocol-ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Instance-ID |
| (64 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 7: Source Protocol subobject in IRO
The code point for the TLV type is TBD8. The TLV length is 12
octets.
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Protocol-ID (8 bits): defined in [RFC7752] section 3.2. IS-IS
[RFC8202] and OSPF [RFC6549] MAY run multiple routing protocol
instances identified by the Protocol-ID over the same link.
Reserved (24 bits): This field MUST be set to zero on transmission
and MUST be ignored on receipt.
Instance-ID (64 bits): defined in [RFC7752] section 3.2.
3.3. XRO Object
As per [RFC5521], XRO is an optional object used to specify exclusion
of certain abstract nodes or resources from the whole path. This
document proposed a set of extensions for topology filter.
3.3.1. Link ID
The Link ID is used to exclude the link that is used during the path
calculation.
The Link ID subobject is defined:
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=TBD9 | Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link ID (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 8: Link ID subobject in XRO
The code point for the TLV type is TBD9. The TLV length is 12
octets.
Link ID (32bits ): defined in IS-IS RFC5307 and OSPF RFC3630.
3.3.2. Admin Group
The Admin Group is used to exclude the links that is used during the
path calculation.
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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=TBD10 | Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Extended Admin Group |
+- -+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 9: Admin Group subobject in XRO
The code point for the TLV type is TBD10. The TLV length is
variable.
Extended Administrative Group: Extended Administrative Group as
defined in [RFC7308].
3.3.3. Source Protocol
The format of the Source Protocol subobject is:
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=TBD11 | Length | Reserved | Protocol-ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Instance-ID |
| (64 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 10: Source Protocol subobject in XRO
The code point for the TLV type is TBD11. The TLV length is 12
octets.
Protocol-ID (8 bits): defined in [RFC7752] section 3.2. IS-IS
[RFC8202] and OSPF [RFC6549] MAY run multiple routing protocol
instances identified by the Protocol-ID over the same link.
Reserved (24 bits): This field MUST be set to zero on transmission
and MUST be ignored on receipt.
Instance-ID (64 bits): defined in [RFC7752] section 3.2.
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3.4. Procedures
A PCC MAY insert a TOPOLOGY object to indicate the sub-topology of an
IGP domain that MUST be considered by the PCE. The PCE will perform
path computation based on the sub-topology identified by the topology
filter rules that can be applied on either the native topology or a
user specified topology. The absence of the TLVs related topology
reference indicates that the filtering rules are to be applied on the
native topology.
4. Acknowledgements
TBA
5. IANA Considerations
5.1. TOPOLOGY Object
IANA is requested to make allocations for Topology Object from the
registry, as follows:
+======+=====================+==========================+
| Type | TLV | Reference |
+======+=====================+==========================+
| TBD1 | Source Protocol TLV | [this document] |
+------+---------------------+--------------------------+
| TBD2 | Multi-topology TLV | [this document] |
+------+---------------------+--------------------------+
| TBD3 | Area TLV | [this document] |
+------+---------------------+--------------------------+
| TBD4 | Algorithm TLV | draft-tokar-pce-sid-algo |
+------+---------------------+--------------------------+
Table 1: TLVs for Topology Object
5.2. IRO Object
IANA is requested to make allocations for IRO Object from the
registry, as follows:
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+======+=================+=================+
| Type | Subobject | Reference |
+======+=================+=================+
| TBD5 | Link ID | [this document] |
+------+-----------------+-----------------+
| TBD6 | Admin Group | [this document] |
+------+-----------------+-----------------+
| TBD7 | Source Protocol | [this document] |
+------+-----------------+-----------------+
Table 2: Subobjects for IRO Object
5.3. XRO Object
IANA is requested to make allocations for XRO Object from the
registry, as follows:
+=======+=================+=================+
| Type | Subobject | Reference |
+=======+=================+=================+
| TBD8 | Link ID | [this document] |
+-------+-----------------+-----------------+
| TBD9 | Admin Group | [this document] |
+-------+-----------------+-----------------+
| TBD10 | Source Protocol | [this document] |
+-------+-----------------+-----------------+
Table 3: Subobjects for XRO Object
6. Security Considerations
TBA
7. References
7.1. Normative References
[draft-ietf-lsr-flex-algo]
"IGP Flexible Algorithm", July 2021, <https://www.rfc-
editor.org/info/draft-ietf-lsr-flex-algo>.
[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>.
[RFC4655] "A Path Computation Element (PCE)-Based Architecture",
August 2006, <https://www.rfc-editor.org/info/RFC4655>.
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[RFC4915] "Multi-Topology (MT) Routing in OSPF", June 2007,
<https://www.rfc-editor.org/info/RFC4915>.
[RFC5120] "M-ISIS: Multi Topology (MT) Routing in Intermediate
System to Intermediate Systems (IS-ISs)", February 2008,
<https://www.rfc-editor.org/info/RFC5120>.
[RFC5440] "Path Computation Element (PCE) Communication Protocol
(PCEP)", March 2009,
<https://www.rfc-editor.org/info/RFC5440>.
[RFC6549] "OSPFv2 Multi-Instance Extensions", March 2012,
<https://www.rfc-editor.org/info/RFC6549>.
[RFC7752] "North-Bound Distribution of Link-State and Traffic
Engineering (TE) Information Using BGP", March 2016,
<https://www.rfc-editor.org/info/RFC7752>.
[RFC8174] "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key
Words", May 2017,
<https://www.rfc-editor.org/info/RFC8174>.
[RFC8202] "IS-IS Multi-Instance", June 2017,
<https://www.rfc-editor.org/info/RFC8202>.
[RFC8231] "Path Computation Element Communication Protocol (PCEP)
Extensions for Stateful PCE", September 2017,
<https://www.rfc-editor.org/info/RFC8231>.
[RFC8795] "YANG Data Model for Traffic Engineering (TE) Topologies",
August 2020, <https://www.rfc-editor.org/info/RFC8795>.
Authors' Addresses
Quan Xiong
ZTE Corporation
China
Email: xiong.quan@zte.com.cn
Shaofu Peng
ZTE Corporation
No.50 Software Avenue
Nanjing
Jiangsu, 210012
China
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Email: peng.shaofu@zte.com.cn
Vishnu Pavan Beeram
Juniper Networks
Email: vbeeram@juniper.net
Tarek Saad
Juniper Networks
Email: tsaad@juniper.net
Mike Koldychev
Cisco Systems
Canada
Email: mkoldych@cisco.com
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