A YANG Data Model for Network Resource Partitions
(NRPs)Huawei Technologies101 Software Avenue, Yuhua DistrictNanjingJiangsu210012Chinalana.wubo@huawei.comHuawei TechnologiesDivyashree Techno ParkBangaloreKarnataka560066Indiadhruv.ietf@gmail.comJuniper Networksvbeeram@juniper.netCisco Systemstsaad.net@gmail.comZTE Corporationpeng.shaofu@zte.com.cn
Routing Area
This document defines a YANG data model for Network Resource
Partitions (NRPs). The model can be used, in particular, for the
realization of the IETF Network Slice Services. defines a
framework for IETF Network Slice Services, which provide connectivity
coupled with network resources commitment between a number of Service
Demarcation Points (SDPs) over a shared network infrastructure. The IETF
Network Slice service is expressed in terms of one or more connectivity
constructs, which can be of a connection type (point-to-point (P2P),
point-to-multipoint (P2MP), or any-to-any (A2A)) and any combination of
these types.This draft defines a YANG module of NRPs for mapping one or more
connection constructs of one or more IETF network slices, for ensuring
SLO and SLE and network scalability. An IETF Network Slice Controller
(NSC) can use it to manage NRP instances in order to implement Network
Slice Services.An NRP Policy is a policy
construct that enables instantiation of mechanisms in support of service
specific control and data plane behaviors on select topological elements
associated with the NRP. describes the detailed
definition of NRP policy in NRP instantiation.According to the YANG model classification of , the NRP model is a network configuration model.The following terms are defined in and are
used in this specification: configuration datastate dataThe following terms are defined in and are
used in this specification: augmentdata modeldata nodeThe terminology for describing YANG data models is found in
.The tree diagram used in this document follows the notation defined
in .There are multiple modes of NRP operations to be supported as
follows:NRP instantiation: Depending on the slice service types and also
network status, there can be two types of approaches. One method is
to create an NRP instance before the network controller processes
the IETF Network Slice service request. Another one is that the
network controller may start creating an NRP instance while
configuring the IETF Network Slice service request.NRP modification: When the capacity of an existing NPR link is
close to capacity, the bandwidth of the link could be increased. And
when the NRP link or node resources are insufficient, new NRP links
and nodes could be added.NRP Deletion: If the NSC determines that no slice service is
using an NRP, the NSC can delete the NRP instance.NRP Monitoring: The NSC can use the NRP model to track and
monitor NRP resource status and usage.An NRP policy specifies the rules for determining the topology
associated with the NRP and dictates how an NRP can be realized in
IP/MPLS networks using one of three partition modes. The NRP policy
dictates if the partitioning of the shared network resources can be
achieved in (a) just the data plane or in (b) just the control plane
or in (c) both the control and data planes.The NRP policy modes (a) and (c) require the forwarding engine on
each NRP capable node to identify the traffic belonging to a specific
NRP and to apply the corresponding Per-Hop Behavior (PHB) or
forwarding mechanism that determines the forwarding treatment of the
packets belonging to the NRP. When catering to IETF Network Slices,
this NRP identification is referred to as the NRP selector and may
comprises of traffic streams from one or more connectivity constructs
(belonging to one or more IETF network slices) mapped to a specific
NRP. The NRP policy modes (b) and (c) require the
distributed/centralized resource reservation management.'nrp-policy' is defined to enable NRP Stateful Traffic Engineering
(NRP-TE) and/or NRP IGP
forwarding in IP/MPLS networks.The tree diagram used in this document follows the notation defined
in .The high-level model structure of NRP policy defined by this
document is as shown in :The 'networks' container from the 'ietf-network' module [RFC8345]
provides a placeholder for an inventory of nodes in the network. This
container is augmented to carry a set of NRP policies.The 'nrp-policies' container carries a list of NRP policies. Each
'nrp-policy' entry is identified by a name and holds the set of
attributes needed to instantiate the NRP. Each entry also carries an
'nrp-id' leaf which uniquely identifies the NRP created by the
enforcement of this policy. TheThe description of the 'nrp-policies' data nodes are as follows,
and the other key elements of each nrp-policy entry are discussed in
the following sub-sections.'nrp-id': Is an identifier that is used to uniquely identify an
NRP instance within the NSC network scope.'mode': Refers to control plane resource partition, data plane
resource partition, or a combination of both types.The 'resource-reservation' container specifies the bandwidth
resource allocated to an NRP instance, or can be overridden by the
configuration of the link specific 'resource-reservation' nodes of
'nrp-topology'.NRP selector defines the data plane encapsulation types and
values that are used to identify NRP-specific network resources. The
data plane mechanism could be based on IP, MPLS, or SRv6
forwarding.'nrp-topology' defines a dedicated NRP topology.When an NRP support IGP forwarding, the topology of the NRP must
be congruent with an IGP instance.The topology used for IGP route
computation and forwarding can be derived using Multi-Topology
Routing (MTR) or Flex-algo. Multi-Topology Routing (MTR) is defined
in , , and or Flex-algo is defined in
.The 'selection' container consists of a list of select subset of
links of an underlay topology or a pre-built topology.The 'filter' container consists of a list of filters where each
entry references a topology filter . The topological
elements that satisfy the membership criteria can optionally
override the default resource-reservation and nrp-selector specific
leafs.The NRP model can be used to track and monitor operational status
and resource usage of NRPs.The device-specific NRP model is defined in module
'ietf-nrp-device' as shown in , which
augments NRP YANG data model in and adds
interface attributes, including resource reservation, NRP selector,
and PHB profile, that are specific to an NRP device.Figure below shows the tree diagram of the device NRP YANG model
defined in modules 'ietf-nrp-device.yang'.The 'ietf-nrp' module uses types defined in . file "ietf-nrp@2023-04-07.yang"
module ietf-nrp {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-nrp";
prefix nrp;
import ietf-network {
prefix nw;
reference
"RFC 8345: A YANG Data Model for Network Topologies";
}
import ietf-network-topology {
prefix nt;
reference
"RFC 8345: A YANG Data Model for Network Topologies";
}
import ietf-routing-types {
prefix rt-types;
reference
"RFC 8294: Common YANG Data Types for the Routing Area";
}
import ietf-te-types {
prefix te-types;
reference
"RFC 8776: Traffic Engineering Common YANG Types";
}
import ietf-te-packet-types {
prefix te-packet-types;
reference
"RFC 8776: Traffic Engineering Common YANG Types";
}
import ietf-srv6-types {
prefix srv6-types;
}
import ietf-inet-types {
prefix inet;
reference
"RFC 6991: Common YANG Data Types";
}
import ietf-access-control-list {
prefix acl;
reference
"RFC 8519: YANG Data Model for Network Access Control Lists
(ACLs)";
}
import ietf-topology-filter {
prefix topo-filt;
reference
"draft-bestbar-teas-yang-topology-filter: YANG Data Model
for Topology Filter";
}
organization
"IETF TEAS Working Group";
contact
"
WG Web:
WG List:
Editor: Bo Wu
Editor: Dhruv Dhody
Editor: Vishnu Pavan Beeram
Editor: Tarek Saad
Editor: Shaofu Peng
";
description
"This YANG module defines a network data module for
NRP(Network Resource Partition).
Copyright (c) 2023 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
(https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself
for full legal notices.";
revision 2023-04-07 {
description
"This is the initial version of NRP YANG model.";
reference
"RFC XXX: A YANG Data Model for Network Resource Partition";
}
/*
* I D E N T I T I E S
*/
identity nrp-partition-mode {
description
"Base identity for nrp partition type.";
}
identity nrp-control-plane-partition {
base nrp-partition-mode;
description
"Identity for control plane partition.";
}
identity nrp-data-plane-partition {
base nrp-partition-mode;
description
"Identity for data plane partition.";
}
identity nrp-hybrid-plane-partition {
base nrp-partition-mode;
description
"Identity for both planes partition.";
}
identity nrp-link-partition-type {
description
"Base identity for interface partition type.";
}
identity virtual-sub-interface-partition {
base nrp-link-partition-type;
description
"Identity for virtual interface or sub-interface, e.g. FlexE.";
}
identity queue-partition {
base nrp-link-partition-type;
description
"Identity for queue partition type.";
}
/*
* Identity:
* MPLS Selector Label Position.
*/
identity selector-mpls-label-position {
description
"Base identity for the position of the MPLS selector label.";
}
identity selector-mpls-label-position-top {
base selector-mpls-label-position;
description
"MPLS selector label is at the top of the label stack.";
}
identity selector-mpls-label-position-bottom {
base selector-mpls-label-position;
description
"MPLS selector label is either at the bottom or at a specific
offset from the bottom of the label stack.";
}
identity selector-mpls-label-position-indicator {
base selector-mpls-label-position;
description
"MPLS selector is preceded by a special purpose
indicator label in the label stack.";
}
/*
* T Y P E D E F S
*/
typedef nrp-acl-ref {
type leafref {
path "/acl:acls/acl:acl/acl:name";
}
description
"This type is used to reference an ACL.";
}
typedef nrp-topo-filter-ref {
type leafref {
path "/nw:networks/topo-filt:topology-filters/"
+ "topo-filt:topology-filter/topo-filt:name";
}
description
"This type is used to reference a Topology Filter.";
}
/*
* Grouping - NRP Resource Reservation
*/
grouping nrp-resource-reservation {
description
"Grouping for NRP resource reservation.";
container resource-reservation {
description
"Container for NRP resource reservation.";
choice max-bw-type {
description
"Choice of maximum bandwidth specification.";
case bw-value {
leaf maximum-bandwidth {
type uint64;
description
"The maximum bandwidth allocated to an NRP
- specified as absolute value.";
}
}
case bw-percentage {
leaf maximum-bandwidth-percent {
type rt-types:percentage;
description
"The maximum bandwidth allocated to an NRP
- specified as percentage of link
capacity.";
}
}
}
}
}
/*
* G R O U P I N G S
*/
/*
* Grouping - MPLS selector label location specific fields
*/
grouping nrp-selector-mpls-label-location {
description
"Grouping for MPLS FAS label location specific fields.";
leaf label-position {
type identityref {
base selector-mpls-label-position;
}
description
"MPLS selector label position.";
}
leaf label-position-offset {
when "derived-from-or-self(../label-position,"
+ "'nrp:selector-mpls-label-position-bottom')" {
description
"MPLS label position offset is relevant only when the
label-position is set to 'bottom'.";
}
type uint8;
description
"MPLS label position offset.";
}
}
/*
* Grouping - NRP Selector Configuration
*/
grouping nrp-selector-config {
description
"Grouping for NRP selector configuration.";
container selector {
description
"Container for NRP selector.";
container ipv4 {
description
"Container for IPv4 NRP selector.";
leaf-list destination-prefix {
type inet:ipv4-prefix;
description
"Any prefix from the specified set of IPv4
destination prefixes can be the selector.";
}
}
container ipv6 {
description
"Container for IPv6 NRP selector.";
choice selector-type {
description
"Choices for IPv6 selector type.";
case dedicated {
leaf ipv6-hbh-eh {
type uint32;
description
"The selector value carried in Hop-by-Hop
Option of IPv6 extension header.";
}
}
case srv6-sid-derived {
leaf-list srv6-sid {
type inet:ipv6-prefix;
description
"Any SID from the specified set of SRv6
SID can be the selector.";
}
}
case ipv6-destination-derived {
leaf-list destination-prefix {
type inet:ipv6-prefix;
description
"Any prefix from the specified set of IPv6
destination prefixes can be the selector.";
}
}
}
}
container mpls {
description
"Container for MPLS NRP selector.";
choice selector-type {
description
"Choices for MPLS label specification.";
case dedicated {
leaf label {
type rt-types:mpls-label;
description
"MPLS selector Label is explicitly
specified.";
}
uses nrp-selector-mpls-label-location;
}
case derived {
leaf forwarding-label {
type empty;
description
"MPLS selector Label is derived from
forwarding label.";
}
}
}
}
leaf-list acl-ref {
type nrp-acl-ref;
description
"Selection is done based on the specified list of ACLs.";
}
}
}
/*
* Grouping - NRP QoS PHB profile
*/
grouping nrp-qos-phb-profile {
description
"Grouping for NRP QoS PHB profile.";
leaf phb-profile {
type string;
description
"PHB profile identifier.";
}
}
/*
* Grouping - NRP IGP congruent
*/
grouping nrp-igp-congruent {
description
"Grouping for NRP IGP congruent attributes.";
container igp-congruent {
presence "indicates NRP IGP congruent";
description
"The presence of the container node indicates NRP IGP
congruent.";
leaf multi-topology-id {
type uint32;
description
"Indicates the MT-id of the NRP IGP instance.";
}
leaf algo-id {
type uint32;
description
"Indicates the algo-id of the NRP IGP instance.";
}
leaf sharing {
type boolean;
default "true";
description
"'true' if the the NRP IGP instance can be shared with
other NRPs;
'false' if the the NRP IGP instance is dedicated
to this NRP.";
}
}
}
/*
* Grouping - NRP Topology Filter
*/
grouping nrp-topology-filter {
description
"Grouping for NRP filter topology.";
container filters {
description
"Container for filters.";
list filter {
key "filter-ref";
description
"List of filters.";
leaf filter-ref {
type nrp-topo-filter-ref;
description
"Reference to a specific topology filter from the
list of global topology filters.";
}
uses nrp-resource-reservation;
uses nrp-selector-config;
uses nrp-qos-phb-profile;
}
}
}
/*
* Grouping - NRP Select Topology
*/
grouping nrp-select-topology {
description
"NRP topology specified by selection.";
container select {
description
"The container of NRP select topology.";
list topology-group {
key "group-id";
description
"List of groups for NRP topology elements (node or links)
that share common attributes.";
leaf group-id {
type string;
description
"The NRP topology group identifier.";
}
container base-topology-ref {
description
"Container for the base topology reference.";
uses nw:network-ref;
}
list links {
key "link-ref";
description
"A list of links with common attributes";
leaf link-ref {
type leafref {
path
"/nw:networks/nw:network[nw:network-id=current()"
+ "/../../base-topology-ref/network-ref]"
+ "/nt:link/nt:link-id";
}
description
"A reference to a link in the base topology.";
}
}
uses nrp-resource-reservation;
leaf link-partition-type {
type identityref {
base nrp-link-partition-type;
}
description
"Indicates the resource reservation type of an NRP link.";
}
uses nrp-qos-phb-profile;
}
}
}
/*
* Grouping - NRP Topology
*/
grouping nrp-topology {
description
"Grouping for NRP topology.";
container topology {
description
"Container for NRP topology.";
uses nrp-igp-congruent;
choice topology-type {
description
"Choice of NRP topology type.";
case selection {
uses nrp-select-topology;
}
case filter {
uses nrp-topology-filter;
}
}
}
}
/*
* Grouping - NRP Policy
*/
grouping nrp-pol {
description
"Grouping for NRP policies.";
container nrp-policies {
description
"Container for nrp policies.";
list nrp-policy {
key "name";
unique "nrp-id";
description
"List of NRP policies.";
leaf name {
type string;
description
"A string that uniquely identifies the NRP policy.";
}
leaf nrp-id {
type uint32;
description
"A 32-bit ID that uniquely identifies the NRP
created by the enforcement of this NRP policy.";
}
leaf mode {
type identityref {
base nrp-partition-mode;
}
default "nrp-hybrid-plane-partition";
description
"Indicates the resource partition mode of the NRP, such as
control plane partition, data plane partition,
or hybrid partition.";
}
uses nrp-resource-reservation;
uses nrp-selector-config;
uses nrp-qos-phb-profile;
uses nrp-topology;
}
}
}
/*
* Grouping - NRP Selector State
*/
grouping nrp-selector-state {
description
"The grouping of NRP selector.";
container selector {
config false;
description
"The container of NRP selector.";
leaf srv6 {
type srv6-types:srv6-sid;
description
"Indicates the SRv6 SID value as the NRP selector.";
}
leaf sr-mpls {
type rt-types:mpls-label;
description
"Indicates the SR MPLS ID value as the NRP selector.";
}
}
}
/*
* Grouping - NRP node attributes
*/
grouping nrp-node-attributes {
description
"NRP node scope attributes.";
container nrp {
config false;
description
"Containing NRP attributes.";
uses nrp-selector-state;
}
}
/*
* Grouping - NRP Link Attributes
*/
grouping nrp-link-attributes {
description
"NRP link scope attributes.";
leaf link-partition-type {
type identityref {
base nrp-link-partition-type;
}
config false;
description
"Indicates the resource partition type of an NRP link.";
}
leaf bandwidth-value {
type uint64;
units "bps";
config false;
description
"Bandwidth allocation for the NRP as absolute value.";
}
uses nrp-selector-state;
}
/*
* Grouping - NRP Bandwidth Metrics
*/
grouping nrp-bandwidth-metrics {
description
"Grouping for NRP bandwidth metrics.";
leaf one-way-available-bandwidth {
type rt-types:bandwidth-ieee-float32;
units "bytes per second";
default "0x0p0";
description
"Available bandwidth that is defined to be NRP link
bandwidth minus bandwidth utilization. For a
bundled link, available bandwidth is defined to be the
sum of the component link available bandwidths.";
}
leaf one-way-utilized-bandwidth {
type rt-types:bandwidth-ieee-float32;
units "bytes per second";
default "0x0p0";
description
"Bandwidth utilization that represents the actual
utilization of the link (i.e. as measured in the router).
For a bundled link, bandwidth utilization is defined to
be the sum of the component link bandwidth
utilizations.";
}
}
// nrp-link-statistics
grouping nrp-statistics-per-link {
description
"Statistics attributes per NRP link.";
container statistics {
config false;
description
"Statistics for NRP link.";
leaf admin-status {
type te-types:te-admin-status;
description
"The administrative state of the link.";
}
leaf oper-status {
type te-types:te-oper-status;
description
"The current operational state of the link.";
}
uses nrp-bandwidth-metrics;
uses te-packet-types:one-way-performance-metrics-packet;
}
}
grouping nrp-topology-type {
description
"Identifies the topology type to be NRP";
container nrp {
presence "indicates NRP topology";
description
"The presence of the container node indicates NRP
topology";
}
}
/*
* Augment - Network Resource Partition Policies.
*/
augment "/nw:networks" {
description
"Augment networks with network resource partition
policies.";
uses nrp-pol;
}
/*
* Augment - NRP type.
*/
augment "/nw:networks/nw:network/nw:network-types" {
description
"Introduces new network type for NRP topology";
uses nrp-topology-type;
}
/*
* Augment - NRP node operational status.
*/
augment "/nw:networks/nw:network/nw:node" {
when '../nw:network-types/nrp:nrp' {
description
"Augment only for NRP topology.";
}
description
"Augment node configuration and state.";
uses nrp-node-attributes;
}
/*
* Augment - NRP link operational status.
*/
augment "/nw:networks/nw:network/nt:link" {
when '../nw:network-types/nrp:nrp' {
description
"Augment only for NRP topology.";
}
description
"Augment link configuration and state.";
container nrp {
config false;
description
"Containing NRP attributes.";
uses nrp-link-attributes;
uses nrp-statistics-per-link;
}
}
/*
* Augment - Native topology with node operational status.
*/
augment "/nw:networks/nw:network/nw:node" {
description
"Augment node with NRP aware attributes.";
list nrps {
key "nrp-id";
config false;
description
"List of NRPs.";
leaf nrp-id {
type uint32;
description
"NRP identifier";
}
uses nrp-node-attributes;
}
}
/*
* Augment - Native topology with link operational status.
*/
augment "/nw:networks/nw:network/nt:link" {
description
"Augment link with NRP attributes.";
list nrps {
key "nrp-id";
config false;
description
"List of NRPs.";
leaf nrp-id {
type uint32;
description
"NRP identifier";
}
uses nrp-link-attributes;
}
}
}
]]>The device NRP YANG module ('ietf-nrp-device') models augments the
NRP YANG module ('ietf-nrp') and adds the attributes of NRP interfaces
that are local to an NRP device.The device NRP YANG module imports the following module(s):
ietf-interfaces defined in , ietf-network
defined in , and NRP grouping defined in this
document. file "ietf-nrp-device@2023-07-24.yang"
module ietf-nrp-device {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-nrp-device";
prefix nrp-dev;
/* Import IETF Network module */
import ietf-network {
prefix nw;
reference
"RFC 8345: A YANG Data Model for Network
Topologies, Section 6.1";
}
/* Import IETF interface module */
import ietf-interfaces {
prefix if;
reference
"RFC8343: A YANG Data Model for Interface Management";
}
/* Import NRP module */
import ietf-nrp {
prefix nrp;
reference
"RFCXXXX: A YANG Data Model for Network Resource Partition";
}
organization
"IETF Traffic Engineering Architecture and Signaling (TEAS)
Working Group";
contact
"WG Web:
WG List:
Editor: Bo Wu
Editor: Dhruv Dhody
Editor: Vishnu Pavan Beeram
Editor: Tarek Saad
Editor: Shaofu Peng
";
description
"This module defines a data model for NRP device configurations,
state. The model fully conforms to the
Network Management Datastore Architecture (NMDA).
Copyright (c) 2023 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
(https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself
for full legal notices.";
// RFC Ed.: replace XXXX with actual RFC number and remove this
// note.
// RFC Ed.: update the date below with the date of RFC publication
// and remove this note.
revision 2023-07-24 {
description
"Initial revision for the NRP device YANG module.";
reference
"RFCXXXX: A YANG Data Model for Network Resource Partition
Device";
}
/* NRP device configuraiton */
augment "/nw:networks/nrp:nrp-policies/nrp:nrp-policy" {
description
"NRP policy list.";
/* NRP Interface Configuration Data */
container interfaces {
description
"Configuration data model for NRP interfaces.";
list interface {
key "interface";
description
"NRP interfaces.";
leaf interface {
type if:interface-ref;
description
"NRP interface name.";
}
uses nrp:nrp-resource-reservation;
uses nrp:nrp-selector-config;
uses nrp:nrp-qos-phb-profile;
}
}
}
}
]]>The YANG model defined in this document is designed to be accessed
via network management protocols such as NETCONF or RESTCONF . The lowest
NETCONF layer is the secure transport layer, and the
mandatory-to-implement secure transport is Secure Shell (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 preconfigured subset of all available NETCONF or RESTCONF protocol
operations and content.There are a number of data nodes defined in this YANG model that 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.nrp-link: A malicious client could attempt to remove a link from a
topology, add a new link. In each case, the structure of the topology
would be sabotaged, and this scenario could, for example, result in an
NRP topology that is less than optimal.The entries in the nodes above include the whole network
configurations corresponding with the NRP, and indirectly create or
modify the PE or P device configurations. Unexpected changes to these
entries could lead to service disruption and/or network misbehavior.This document registers a URI in the IETF XML registry . Following the format in ,
the following registration is requested to be made:This document requests to register a YANG module in the YANG Module
Names registry .The authors would like to thank Krzysztof Szarkowicz, Jie Dong, Qin
Wu, Yao Zhao, Zhenbing Li, Ying Cheng, Liyan Gong, and many others for
their helpful comments and suggestions.The following individuals, authors of and , contributed to this consolidated
document: This section contains an example of an instance data tree in JSON
encoding . The example below instantiates an NRP
for the topology that is depicted in the following diagram. There are
three nodes, D1, D2, and D3. D1 has three termination points, 1-0-1,
1-2-1, and 1-3-1. D2 has three termination points as well, 2-1-1, 2-0-1,
and 2-3-1. D3 has two termination points, 3-1-1 and 3-2-1. In addition
there are six links, two between each pair of nodes with one going in
each direction.| | 2-1-1 | |
| | 1-2-1 | |<----------------| | 2-0-1 | |
\-/ 1-3-1 \-/ \-/ 2-3-1 \-/
| /----\ | | /----\ |
+---| |---+ +---| |---+
\----/ \----/
| | | |
| | | |
| | | |
| | +------------+ | |
| | | D3 | | |
| | /-\ /-\ | |
| +----->| | 3-1-1 | |-------+ |
+---------| | 3-2-1 | |<---------+
\-/ \-/
| |
+------------+
]]>An corresponding IGP congruent NRP instance data tree is depicted
below:In addition, an exampe of an NRP that supports the control plane
partition mode is shown in the following figure.
]]>