A YANG Data Model for Segment Routing (SR) Policy and SR in IPv6 (SRv6) support in Path Computation Element Communications Protocol (PCEP)Huawei TechnologiesHuawei Campus, No. 156 Beiqing Rd.Beijing100095Chinac.l@huawei.comCiena Corporationssivabal@ciena.comHuawei TechnologiesHuawei Campus, No. 156 Beiqing Rd.Beijing100095Chinapengshuping@huawei.comCisco Systems, Inc.mkoldych@cisco.comMTN CameroonCameroonLuc-Fabrice.Ndifor@mtn.com
Routing
PCE Working GroupThis document augments a YANG data model for the management of
Path Computation Element Communications Protocol (PCEP) for
communications between a Path Computation Client (PCC) and a Path
Computation Element (PCE), or between two PCEs in support for Segment Routing in IPv6 (SRv6) and SR Policy. The data model
includes configuration data and state data (status information and
counters for the collection of statistics).The Path Computation Element (PCE) defined in
is an entity that is capable of computing a network path or route
based on a network graph, and applying computational constraints.
A Path Computation Client (PCC) may make requests to a PCE for paths
to be computed.PCEP is the communication protocol between a PCC and PCE and is
defined in . PCEP interactions include path
computation requests and path computation replies as well as
notifications of specific states related to the use of a PCE in the
context of Multiprotocol Label Switching (MPLS) and Generalized MPLS
(GMPLS) Traffic Engineering (TE).
specifies extensions to PCEP to enable stateful control of MPLS TE LSPs. extends
to support SR for IPv6 data plane. defines a YANG data model
for the management of PCEP speakers. This document contains a specification of the PCEP-SRv6 YANG module,
"ietf-pcep-srv6" which provides the PCEP-SRv6 data
model. This document also contains the PCEP SR Policy YANG module, "ietf-pcep-srpolicy" which provides a reference to SR Policies .The PCEP operational state is included in the same tree as the PCEP
configuration consistent with Network Management Datastore
Architecture (NMDA) .
The origin of the data is indicated as per the origin metadata
annotation.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 when, and only when, they
appear in all capitals, as shown here.
This document also uses the following terms defined in
:
PCEP entity: a local PCEP speaker.
PCEP peer: a remote PCEP speaker.
PCEP speaker: where it is not necessary to distinguish between local
and remote.
Further, this document also uses the following terms defined in
:
Stateful PCE, Passive Stateful PCE, Active Stateful PCE.
Delegation, Revocation, Redelegation.
LSP State Report, Path Computation Report message (PCRpt).LSP State Update, Path Computation Update message (PCUpd). :
PCE-initiated LSP, Path Computation LSP Initiate Message (PCInitiate). :
Path Setup Type (PST). :
Segment Routing (SR). :
Segment Routing in IPv6 (SRv6). :
SR Policy.A simplified graphical representation of the data model is used in this
document. The meaning of the symbols in these diagrams is defined in .
In this document, names of data nodes and other data
model objects are often used without a prefix, as long as it is clear
from the context in which YANG module each name is defined.
Otherwise, names are prefixed using the standard prefix associated
with the corresponding YANG module, as shown in .PrefixYANG moduleReferenceinetietf-inet-typeste-typesietf-te-typespcepietf-pcepsrv6-typesietf-srv6-typessr-policy-typesietf-sr-policy-typesFollowing additional documents are referenced in the model defined in this
document -TitleReferencePCEP Extensions for Segment Routing leveraging the IPv6 data planeCarrying Binding Label/Segment Identifier (SID) in PCE-based NetworksSegment Routing Policy ArchitecturePCEP Extensions for Signaling Multipath Information defines a mechanism to
encode multiple paths for a single set of objectives and constraints.
This is a generic PCEP mechanism, not specific to any path setup type
or dataplane but the key usecase is SR.Further discussion is needed on how to model it in PCEP YANG.The PCEP-SRv6 YANG module defined in this document has all the common
building blocks for the PCEP-SRv6 extension. The model augments PCEP capabilities at the Entity and peer level with SRv6 capability in PCEP, support for NAI, MSD and the SID structure. The model also extends the LSP in the LSP-DB to maintain SRv6 paths.
The PCEP-SRPolicy YANG module defined in this document has all the common
building blocks for the PCEP-SR Policy extension. The model augments the LSP in the LSPDB to have information refering to the SR Policy and the candidate path.
The sr-policy container is applicable for both SR-MPLS and SRv6.RFC Ed.: In this section, replace all occurrences of 'XXXX' with the
actual RFC number and all occurrences of the revision date below with
the date of RFC publication (and remove this note).
file "ietf-pcep-srv6@2022-07-11.yang"
module ietf-pcep-srv6 {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-pcep-srv6";
prefix pcep-srv6;
import ietf-srv6-types {
prefix srv6-types;
reference
"I-D.ietf-spring-srv6-yang: YANG Data Model for SRv6
Base and Static";
}
import ietf-te-types {
prefix te-types;
reference
"RFC 8776: Common YANG Data Types for Traffic Engineering";
}
import ietf-pcep {
prefix pcep;
reference
"I-D.ietf-pce-pcep-yang: A YANG Data Model for Path
Computation Element Communications Protocol (PCEP)";
}
organization
"IETF PCE (Path Computation Element) Working Group";
contact
"WG Web:
WG List:
Editor: Cheng Li
Shuping Peng
";
description
"The YANG module augments the Path Computation Element
Communications Protocol (PCEP) YANG operational model
with Segment Routing in IPv6 (SRv6).
Copyright (c) 2022 IETF Trust and the persons identified as
authors of the code. All rights reserved.
Redistribution and use in source and binary forms, with or
without modification, is permitted pursuant to, and subject
to the license terms contained in, the Revised BSD License
set forth in Section 4.c of the IETF Trust's Legal Provisions
Relating to IETF Documents
(https://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC XXXX; see the
RFC itself for full legal notices.";
revision 2022-07-11 {
description
"Initial revision.";
reference
"RFC XXXX: A YANG Data Model for Segment Routing (SR) Policy
and SRv6 support in Path Computation Element Communications
Protocol (PCEP)";
}
/* Features */
feature srv6 {
description
"Support Segment Routing in IPv6 (SRv6) for PCE.";
reference
"I-D.ietf-pce-segment-routing-ipv6: PCEP Extensions
for Segment Routing leveraging the IPv6 data plane";
}
feature bsid {
description
"Support Binding SID for PCE.";
reference
"I-D.ietf-pce-binding-label-sid: Carrying Binding
Label/Segment Identifier (SID) in PCE-based Networks.";
}
feature sid-str {
description
"Support for SID Structure";
reference
"I-D.ietf-pce-segment-routing-ipv6: PCEP Extensions
for Segment Routing leveraging the IPv6 data plane";
}
/* Identity */
identity path-setup-srv6 {
if-feature "srv6";
base te-types:path-signaling-type;
description
"SRv6 path setup type";
}
/* Groupings */
grouping srv6-msd {
description
"SRv6 MSD";
leaf msd-type {
type uint8;
description
"SRv6 Maximum Segment Depth (MSD) Type";
}
leaf msd-value {
type uint8;
description
"SRv6 MSD value for the type";
}
reference
"I-D.ietf-pce-segment-routing-ipv6: PCEP Extensions
for Segment Routing leveraging the IPv6 data plane";
}
grouping srv6 {
description
"SRv6";
container srv6 {
if-feature "srv6";
description
"If SRv6 is supported";
leaf enabled {
type boolean;
description
"Enabled or Disabled; set to true when
Enabled";
}
leaf nai {
type boolean;
default "false";
description
"True indicates capability to resolve Node or
Adjacency Identifier (NAI) to SRv6 Segment
Identifier (SID)";
}
leaf msd-limit {
type boolean;
default "false";
description
"True indicates no limit on MSD, the
list srv6-msd is ignored";
}
list srv6-msd {
key "msd-type";
description
"list of SRv6 MSD";
uses srv6-msd;
}
}
}
grouping segment-list {
description
"Segment list grouping";
container segment-list {
description
"Segments for given segment list";
list segment {
key "index";
description
"Configure Segment/hop at the index";
uses segment-properties;
}
}
}
grouping segment-properties {
description
"Segment properties grouping";
leaf index {
type uint32;
description
"Segment index";
}
leaf sid-value {
type srv6-types:srv6-sid;
description
"SRv6 SID value";
}
uses sid-str;
leaf endpoint-behavior {
type identityref {
base srv6-types:srv6-endpoint-type;
}
description
"The behavior associated with the SRv6 SIDs.";
}
/*Query: Add NAI?*/
}
grouping sid-str {
description
"The default SID Structure";
container sid-str {
if-feature "sid-str";
description
"The default SID Structure";
leaf lb {
type uint8;
description
"SRv6 SID Locator Block length in bits";
}
leaf ln {
type uint8;
description
"SRv6 SID Locator Node length in bits";
}
leaf fn {
type uint8;
description
"SRv6 SID Function length in bits";
}
leaf an {
type uint8;
description
"SRv6 SID Arguments length in bits";
}
}
}
/*
* Augment modules to add SRv6
*/
augment "/pcep:pcep/pcep:entity/pcep:capabilities" {
description
"Augmenting SRv6";
uses srv6;
uses sid-str;
}
augment "/pcep:pcep/pcep:entity/pcep:peers/pcep:peer"
+ "/pcep:capabilities" {
description
"Augmenting SRv6";
uses srv6;
}
augment "/pcep:pcep/pcep:entity/pcep:lsp-db/pcep:lsp" {
description
"Augmenting SRv6";
container srv6 {
when
"derived-from-or-self
(/pcep:pcep/pcep:entity/pcep:lsp-db/pcep:lsp/pcep:pst,
'path-setup-srv6')" {
description
"For SRv6 path";
}
if-feature "srv6";
uses segment-list;
description
"SRv6";
}
}
}
]]>RFC Ed.: In this section, replace all occurrences of 'XXXX' with the
actual RFC number and all occurrences of the revision date below with
the date of RFC publication (and remove this note).
file "ietf-pcep-srpolicy@2022-07-11.yang"
module ietf-pcep-srpolicy {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-pcep-srpolicy";
prefix pcep-srp;
import ietf-inet-types {
prefix inet;
reference
"RFC 6991: Common YANG Data Types";
}
import ietf-pcep {
prefix pcep;
reference
"I-D.ietf-pce-pcep-yang: A YANG Data Model for Path
Computation Element Communications Protocol (PCEP)";
}
import ietf-sr-policy-types {
prefix sr-policy-types;
reference
"I-D.ietf-spring-sr-policy-yang: YANG Data Model for
Segment Routing Policy";
}
organization
"IETF PCE (Path Computation Element) Working Group";
contact
"WG Web:
WG List:
Editor: Cheng Li
Shuping Peng
";
description
"The YANG module augments the Path Computation Element
Communications Protocol (PCEP) YANG model with Segment
Routing (SR) Policy.
Copyright (c) 2022 IETF Trust and the persons identified as
authors of the code. All rights reserved.
Redistribution and use in source and binary forms, with or
without modification, is permitted pursuant to, and subject
to the license terms contained in, the Revised BSD License
set forth in Section 4.c of the IETF Trust's Legal Provisions
Relating to IETF Documents
(https://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC XXXX; see the
RFC itself for full legal notices.";
revision 2022-07-11 {
description
"Initial revision.";
reference
"RFC XXXX: A YANG Data Model for Segment Routing (SR) Policy
and SRv6 support in Path Computation Element Communications
Protocol (PCEP)";
}
/* Features */
feature multipath {
description
"Support for multipath ERO.";
reference
"I-D.ietf-pce-multipath: PCEP Extensions for Signaling
Multipath Information";
}
/* Groupings */
grouping sr-policy {
description
"Segment Routing Policy grouping";
leaf headend {
type inet:ip-address-no-zone;
description
"SR Policy headend";
reference
"I-D.ietf-spring-segment-routing-policy: Segment
Routing Policy Architecture";
}
leaf color {
type uint32 {
range "1..max";
}
description
"SR Policy Color";
reference
"I-D.ietf-spring-segment-routing-policy: Segment
Routing Policy Architecture";
}
leaf endpoint {
type inet:ip-address-no-zone;
description
"SR Policy Endpoint";
reference
"I-D.ietf-spring-segment-routing-policy: Segment
Routing Policy Architecture";
}
}
grouping sr-policy-cp {
description
"Segment Routing Policy Candidate Path grouping";
leaf protocol-origin {
type sr-policy-types:protocol-origin-type;
description
"SR Policy Candidate Path Protocol";
reference
"I-D.ietf-spring-segment-routing-policy: Segment
Routing Policy Architecture";
}
leaf originator {
type string;
description
"SR Policy Candidate Path Originator";
reference
"I-D.ietf-spring-segment-routing-policy: Segment
Routing Policy Architecture";
}
leaf discriminator {
type uint32 {
range "1..max";
}
description
"SR Policy Candidate Path Discriminator";
reference
"I-D.ietf-spring-segment-routing-policy: Segment
Routing Policy Architecture";
}
}
augment "/pcep:pcep/pcep:entity/pcep:lsp-db/pcep:lsp" {
description
"Augmenting SR Policy";
container sr-policy {
when
"derived-from-or-self
(/pcep:pcep/pcep:entity/pcep:lsp-db/pcep:lsp/pcep:pst,
'path-setup-sr') or
derived-from-or-self
(/pcep:pcep/pcep:entity/pcep:lsp-db/pcep:lsp/pcep:pst,
'path-setup-srv6')" {
description
"Applicable for SR or SRv6";
}
uses sr-policy;
uses sr-policy-cp;
description
"SR Policy Candidate Path";
}
}
}
]]>The YANG module defined in this document is designed to be accessed via
network management protocol such as NETCONF
or RESTCONF . The lowest NETCONF layer is the secure
transport layer and the mandatory-to-implement secure transport is
SSH . The lowest RESTCONF layer is HTTPS, and the
mandatory-to-implement secure transport is TLS The NETCONF access control model provides
the means to restrict access for particular NETCONF or RESTCONF users to a
pre-configured subset of all available NETCONF or RESTCONF protocol
operations and content.There are a number of data nodes defined in the YANG module which are
writable/creatable/deletable (i.e., config true, which is the
default). These data nodes may be considered sensitive or vulnerable
in some network environments. Write operations (e.g., <edit-config>)
to these data nodes without proper protection can have a negative
effect on network operations. These are the subtrees and data nodes and
their sensitivity/vulnerability:
/pcep:pcep/pcep:entity/pcep:capabilities/pcep-srv6:srv6 - configure local SRv6 capability and parameters./pcep:pcep/pcep:entity/pcep:peers/pcep:peer/pcep:capabilities/pcep-srv6:srv6 - configure peer's SRv6 capability and parameters.Unauthorized access to above list can adversely affect the
PCEP session between the local entity and the peers. This may
lead to inability to compute new paths, stateful operations on
the delegated as well as PCE-initiated LSPs.Some of the readable data nodes in this YANG module may be considered
sensitive or vulnerable in some network environments. It is thus important
to control read access (e.g., via get, get-config, or notification) to
these data nodes. These are the subtrees and data nodes and their
sensitivity/vulnerability:
/pcep:pcep/pcep:entity/pcep:lsp-db/pcep:lsp/pcep-srv6:srv6 - The SRv6 SID in the network. Unauthorized access to
this could provide entire path and network usage information./pcep:pcep/pcep:entity/pcep:lsp-db/pcep:lsp/pcep-srpolicy:sr-policy - The reference to SR Policy. Unauthorized access to
this could provide SR Policy usage information.This document registers a URI in the "IETF XML Registry"
.
Following the format in RFC 3688, the following registration has been
made.
urn:ietf:params:xml:ns:yang:ietf-pcep-srv6The PCE WG of the IETF.N/A; the requested URI is an XML namespace.urn:ietf:params:xml:ns:yang:ietf-pcep-srpolicyThe PCE WG of the IETF.N/A; the requested URI is an XML namespace.This document registers a YANG module in the "YANG Module Names"
registry .
The authors would like to thank Dhruv Dhody for the initial YANG model.