A YANG Data Model for
Routing ManagementCZ.NIClhotka@nic.czCisco Systemsacee@cisco.com
Operations and Management
NETMOD Working GroupThis document contains a specification of three YANG modules
and one submodule. Together they form the core routing data
model which serves as a framework for configuring and managing a
routing subsystem. It is expected that these modules will be
augmented by additional YANG modules defining data models for
control plane protocols, route filters and other functions. The core
routing data model provides common building blocks for such
extensions -- routes, routing information bases (RIB), and
control plane protocols.This document contains a specification of the following YANG
modules:
Module "ietf-routing" provides generic components of a
routing data model.Module "ietf-ipv4-unicast-routing" augments the
"ietf-routing" module with additional data specific to IPv4
unicast.Module "ietf-ipv6-unicast-routing" augments the
"ietf-routing" module with additional data specific to IPv6
unicast. Its submodule "ietf-ipv6-router-advertisements" also
augments the "ietf-interfaces" and
"ietf-ip" modules with IPv6 router
configuration variables required by .These modules together define the so-called core routing data
model, which is intended as a basis for future data model
development covering more sophisticated routing systems. While
these three modules can be directly used for simple IP devices
with static routing (see ), their
main purpose is to provide essential building blocks for more
complicated data models involving multiple control plane protocols,
multicast routing, additional address families, and advanced
functions such as route filtering or policy routing. To this
end, it is expected that the core routing data model will be
augmented by numerous modules developed by other IETF working
groups.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 .The following terms are defined in :
client,message,protocol operation,server.The following terms are defined in :
action,augment,configuration data,container,container with presence,data model,data node,feature,leaf,list,mandatory node,module,schema tree,state data,RPC operation. YANG data model
comprising "ietf-routing", "ietf-ipv4-unicast-routing" and
"ietf-ipv6-unicast-routing" modules.a route to a directly connected
network.An object
containing a list of routes together with other
information. See for details.An entry of a list in
state data ("config false") that is created by the system
independently of what has been explicitly configured. See
for details.An entry of a list in
state data ("config false") that is created and deleted as a
direct consequence of certain configuration changes. See
for details.A simplified graphical representation of the complete data
tree is presented in , and similar
diagrams of its various subtrees appear in the main text.Brackets "[" and "]" enclose list keys.Curly braces "{" and "}" contain names of optional features that
make the corresponding node conditional.Abbreviations before data node names: "rw" means configuration
(read-write), "ro" state data (read-only), "-x" RPC operations or
actions, and "-n" notifications.Symbols after data node names: "?" means an optional node, "!" a
container with presence, and "*" denotes a "list" or "leaf-list".Parentheses enclose choice and case nodes, and case nodes are
also marked with a colon (":").Ellipsis ("...") stands for contents of subtrees that are not
shown.In this document, names of data nodes, actions 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 moduleReferenceifietf-interfacesipietf-iprtietf-routingv4urietf-ipv4-unicast-routingv6urietf-ipv6-unicast-routingyangietf-yang-typesinetietf-inet-typesThe initial design of the core routing data model was driven by
the following objectives:
The data model should be suitable for the common address
families, in particular IPv4 and IPv6, and for unicast and
multicast routing, as well as Multiprotocol Label Switching
(MPLS).A simple IP routing system, such as one that uses only
static routing, should be configurable in a simple way,
ideally without any need to develop additional YANG
modules.On the other hand, the core routing framework must allow
for complicated implementations involving multiple routing
information bases (RIB) and multiple control plane protocols, as
well as controlled redistributions of routing information.Device vendors will want to map the data models built on this
generic framework to their proprietary data models and
configuration interfaces. Therefore, the framework should be
flexible enough to facilitate such a mapping and accommodate
data models with different logic.The core routing data model consists of three YANG modules
and one submodule. The first module, "ietf-routing", defines the
generic components of a routing system. The other two modules,
"ietf-ipv4-unicast-routing" and "ietf-ipv6-unicast-routing",
augment the "ietf-routing" module with additional data nodes
that are needed for IPv4 and IPv6 unicast routing,
respectively. Module "ietf-ipv6-unicast-routing" has a
submodule, "ietf-ipv6-router-advertisements", that augments the
"ietf-interfaces" and "ietf-ip" modules with configuration variables for IPv6
router advertisements as required by . Figures and show abridged views of the configuration and
state data hierarchies. See for
the complete data trees.As can be seen from Figures and , the core routing data model introduces
several generic components of a routing framework: routes, RIBs
containing lists of routes, and control plane protocols. describes these components in
more detail.The core routing data model defines several lists in the
schema tree, such as "rib", that have to be populated with at
least one entry in any properly functioning device, and
additional entries may be configured by a client.In such a list, the server creates the required item as a
so-called system-controlled entry in state data, i.e., inside
the "routing-state" container.An example can be seen in : the
"/routing-state/ribs/rib" list has two
system-controlled entries named "ipv4-master" and
"ipv6-master".Additional entries may be created in the configuration by
a client, e.g., via the NETCONF protocol. These are so-called
user-controlled entries. If the server accepts a configured
user-controlled entry, then this entry also appears in the
state data version of the list.Corresponding entries in both versions of the list (in
state data and configuration) have the same value of the list
key.A client may also provide supplemental configuration of
system-controlled entries. To do so, the client creates a new
entry in the configuration with the desired contents. In order
to bind this entry to the corresponding entry in the state
data list, the key of the configuration entry has to be set to
the same value as the key of the state entry.Deleting a user-controlled entry from the configuration list
results in the removal of the corresponding entry in the
state data list. In contrast, if a system-controlled
entry is deleted from the configuration list, only the extra
configuration specified in that entry is removed but the
corresponding state data entry remains in the list.This section describes the essential components of the core
routing data model.Routes are basic elements of information in a routing
system. The core routing data model defines only the following
minimal set of route attributes:
"destination-prefix": address prefix specifying the set
of destination addresses for which the route may be
used. This attribute is mandatory."route-preference": an integer value (also known as
administrative distance) that is used for selecting a
preferred route among routes with the same destination
prefix. A lower value means a more preferred route."next-hop": determines the outgoing interface and/or
next-hop address(es), other operation to be performed with a
packet.Routes are primarily state data that appear as entries of
RIBs () but they may also be found in
configuration data, for example as manually configured static
routes. In the latter case, configurable route attributes are
generally a subset of attributes defined for RIB routes.Every implementation of the core routing data model manages
one or more routing information bases (RIB). A RIB is a list
of routes complemented with administrative data. Each RIB
contains only routes of one address family. An address family
is represented by an identity derived from the
"rt:address-family" base identity.In the core routing data model, RIBs are state data
represented as entries of the list
"/routing-state/ribs/rib". The contents of
RIBs are controlled and manipulated by control plane protocol
operations which may result in route additions, removals and
modifications. This also includes manipulations via the
"static" and/or "direct" pseudo-protocols, see .For every supported address family, exactly one RIB MUST be
marked as the so-called default RIB. Its role is explained in
.Simple router implementations that do not advertise the
feature "multiple-ribs" will typically create one
system-controlled RIB per supported address family, and mark
it as the default RIB.More complex router implementations advertising the
"multiple-ribs" feature support multiple RIBs per address
family that can be used for policy routing and other
purposes.The following action (see Section 7.15 of ) is defined for the
"rib" list:
active-route -- return the active RIB route for the
destination address that is specified as the action's input
parameter.The core routing data model provides an open-ended
framework for defining multiple control plane protocol
instances, e.g., for Layer 3 routing protocols. Each control
plane protocol instance MUST be assigned a type, which is an
identity derived from the "rt:control-plane-protocol" base
identity. The core routing data model defines two identities
for the direct and static pseudo-protocols ().Multiple control plane protocol instances of the same type MAY be
configured.The core routing data model defines two special routing
protocol types -- "direct" and "static". Both are in fact
pseudo-protocols, which means that they are confined to the
local device and do not exchange any routing information
with adjacent routers.Every implementation of the core routing data model MUST
provide exactly one instance of the "direct" pseudo-protocol
type. It is the source of direct routes for all configured
address families. Direct routes are normally supplied by the
operating system kernel, based on the configuration of
network interface addresses, see .A pseudo-protocol of the type "static" allows for specifying
routes manually. It MAY be configured in zero or multiple
instances, although a typical configuration will have exactly
one instance.It is expected that future YANG modules will create data
models for additional control plane protocol types. Such a new
module has to define the protocol-specific configuration and
state data, and it has to integrate it into the core routing
framework in the following way:
A new identity MUST be defined for the control plane protocol
and its base identity MUST be set to "rt:control-plane-protocol",
or to an identity derived from "rt:control-plane-protocol".Additional route attributes MAY be defined, preferably in
one place by means of defining a YANG grouping. The new
attributes have to be inserted by augmenting the definitions
of the nodes
and
and possibly other places in the configuration, state
data, notifications, and input/output parameters of
actions or RPC operations.Configuration parameters and/or state data for the new
protocol can be defined by augmenting the
"control-plane-protocol" data node under both "/routing"
and "/routing-state".By using a "when" statement, the augmented configuration
parameters and state data specific to the new protocol
SHOULD be made conditional and valid only if the value of
"rt:type" or "rt:source-protocol" is equal to (or derived
from) the new protocol's identity.It is also RECOMMENDED that protocol-specific data nodes
be encapsulated in an appropriately named container with
presence. Such a container may contain mandatory data nodes
that are otherwise forbidden at the top level of an
augment.The above steps are implemented by the example YANG module
for the RIP routing protocol in .YANG module "ietf-ipv6-router-advertisements" (), which is a submodule of the
"ietf-ipv6-unicast-routing" module, augments the configuration
and state data of IPv6 interfaces with definitions of the
following variables as required by ,
sec. 6.2.1:
send-advertisements,max-rtr-adv-interval,min-rtr-adv-interval,managed-flag,other-config-flag,link-mtu,reachable-time,retrans-timer,cur-hop-limit,default-lifetime,prefix-list: a list of prefixes to be advertised.The
following parameters are associated with each prefix in the
list:
valid-lifetime,on-link-flag,preferred-lifetime,autonomous-flag.NOTES:The "IsRouter" flag, which is also required by , is implemented in the "ietf-ip" module
(leaf "ip:forwarding").The original specification
allows the implementations to decide whether the
"valid-lifetime" and "preferred-lifetime" parameters remain
the same in consecutive advertisements, or decrement in real
time. However, the latter behavior seems problematic because
the values might be reset again to the (higher) configured
values after a configuration is reloaded. Moreover, no
implementation is known to use the decrementing
behavior. The "ietf-ipv6-router-advertisements" submodule
therefore stipulates the former behavior with constant
values.The semantics of the core routing data model also depends on
several configuration parameters that are defined in other YANG
modules.The following boolean switch is defined in the
"ietf-interfaces" YANG module :
If this switch is set to "false" for a network layer
interface, then all routing and forwarding functions MUST
be disabled on that interface.
The following boolean switches are defined in the "ietf-ip"
YANG module :
If this switch is set to "false" for a network layer
interface, then all IPv4 routing and forwarding functions
MUST be disabled on that interface.
If this switch is set to "false" for a network layer
interface, then the forwarding of IPv4 datagrams through
this interface MUST be disabled. However, the interface MAY
participate in other IPv4 routing functions, such as routing
protocols.
If this switch is set to "false" for a network layer
interface, then all IPv6 routing and forwarding functions
MUST be disabled on that interface.
If this switch is set to "false" for a network layer
interface, then the forwarding of IPv6 datagrams through
this interface MUST be disabled. However, the interface MAY
participate in other IPv6 routing functions, such as routing
protocols.
In addition, the "ietf-ip" module allows for configuring IPv4
and IPv6 addresses and network prefixes or masks on network
layer interfaces. Configuration of these parameters on an
enabled interface MUST result in an immediate creation of the
corresponding direct route. The destination prefix of this route
is set according to the configured IP address and network
prefix/mask, and the interface is set as the outgoing interface
for that route.RFC Editor: 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).RFC Editor: 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).RFC Editor: 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).RFC Editor: 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).RFC Ed.: In this section, replace all occurrences of 'XXXX' with
the actual RFC number (and remove this note).This document registers the following namespace URIs in the
IETF XML registry :This document registers the following YANG modules in the YANG
Module Names registry :This document registers the following YANG submodule in the YANG
Module Names registry :Configuration and state data conforming to the core routing
data model (defined in this document) are designed to be
accessed via a management protocol with secure transport layer,
such as NETCONF . The NETCONF access
control model provides the means to
restrict access for particular NETCONF users to a pre-configured
subset of all available NETCONF protocol operations and
content.A number of configuration data nodes defined in the YANG
modules belonging to the core routing data model are
writable/creatable/deletable (i.e., "config true" in YANG terms,
which is the default). These data nodes may be considered
sensitive or vulnerable in some network environments. Write
operations to these data nodes, such as "edit-config" in
NETCONF, can have negative effects on the network if the
protocol operations are not properly protected.The vulnerable "config true" parameters and subtrees are the
following:
This
list specifies the control plane protocols configured on a
device.This list
specifies the RIBs configured for the device.
Unauthorised access to any of these lists can adversely affect the
routing subsystem of both the local device and the network. This
may lead to network malfunctions, delivery of packets to
inappropriate destinations and other problems.The authors wish to thank Nitin Bahadur, Martin Bjorklund,
Dean Bogdanovic, Jeff Haas, Joel Halpern, Wes Hardaker,
Sriganesh Kini, David Lamparter, Andrew McGregor, Jan Medved,
Xiang Li, Stephane Litkowski, Thomas Morin, Tom Petch,
Yingzhen Qu, Bruno Rijsman, Juergen Schoenwaelder, Phil Shafer,
Dave Thaler, Yi Yang, Derek Man-Kit Yeung and Jeffrey Zhang for
their helpful comments and suggestions.Key words for use in RFCs to Indicate Requirement LevelsIn many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements.The IETF XML RegistryThis document describes an IANA maintained registry for IETF standards which use Extensible Markup Language (XML) related items such as Namespaces, Document Type Declarations (DTDs), Schemas, and Resource Description Framework (RDF) Schemas.Neighbor Discovery for IP version 6 (IPv6)This document specifies the Neighbor Discovery protocol for IP Version 6. IPv6 nodes on the same link use Neighbor Discovery to discover each other's presence, to determine each other's link-layer addresses, to find routers, and to maintain reachability information about the paths to active neighbors. [STANDARDS-TRACK]YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)YANG is a data modeling language used to model configuration and state data manipulated by the Network Configuration Protocol (NETCONF), NETCONF remote procedure calls, and NETCONF notifications. [STANDARDS-TRACK]Common YANG Data TypesThis document introduces a collection of common data types to be used with the YANG data modeling language. This document obsoletes RFC 6021.Network Configuration Protocol (NETCONF)The Network Configuration Protocol (NETCONF) defined in this document provides mechanisms to install, manipulate, and delete the configuration of network devices. It uses an Extensible Markup Language (XML)-based data encoding for the configuration data as well as the protocol messages. The NETCONF protocol operations are realized as remote procedure calls (RPCs). This document obsoletes RFC 4741. [STANDARDS-TRACK]A YANG Data Model for Interface ManagementThis document defines a YANG data model for the management of network interfaces. It is expected that interface-type-specific data models augment the generic interfaces data model defined in this document. The data model includes configuration data and state data (status information and counters for the collection of statistics).A YANG Data Model for IP ManagementThis document defines a YANG data model for management of IP implementations. The data model includes configuration data and state data.The YANG 1.1 Data Modeling LanguageYANG is a data modeling language used to model configuration data, state data, remote procedure calls, and notifications for network management protocols. This document describes the syntax and semantics of version 1.1 of the YANG language. YANG version 1.1 is a maintenance release of the YANG language, addressing ambiguities and defects in the original specification. There are a small number of backward incompatibilities from YANG version 1. This document also specifies the YANG mappings to the Network Configuration Protocol (NETCONF).Guidelines for Authors and Reviewers of YANG Data Model DocumentsThis memo provides guidelines for authors and reviewers of Standards Track specifications containing YANG data model modules. Applicable portions may be used as a basis for reviews of other YANG data model documents. Recommendations and procedures are defined, which are intended to increase interoperability and usability of Network Configuration Protocol (NETCONF) implementations that utilize YANG data model modules. This document is not an Internet Standards Track specification; it is published for informational purposes.Network Configuration Protocol (NETCONF) Access Control ModelThe standardization of network configuration interfaces for use with the Network Configuration Protocol (NETCONF) requires a structured and secure operating environment that promotes human usability and multi-vendor interoperability. There is a need for standard mechanisms to restrict NETCONF protocol access for particular users to a pre-configured subset of all available NETCONF protocol operations and content. This document defines such an access control model. [STANDARDS-TRACK]YANG Module LibraryThis document describes a YANG library that provides information about all the YANG modules used by a network management server (e.g., a Network Configuration Protocol (NETCONF) server). Simple caching mechanisms are provided to allow clients to minimize retrieval of this information.JSON Encoding of Data Modeled with YANGThis document defines encoding rules for representing configuration data, state data, parameters of RPC operations or actions, and notifications defined using YANG as JavaScript Object Notation (JSON) text.This appendix presents the complete configuration and
state data trees of the core routing data model.
See for an explanation of the
symbols used. Data type of every leaf node is shown near the right
end of the corresponding line.Some parts and options of the core routing model, such as
user-defined RIBs, are intended only for advanced routers. This
appendix gives basic non-normative guidelines for implementing a
bare minimum of available functions. Such an implementation may
be used for hosts or very simple routers.A minimum implementation does not support the feature
"multiple-ribs". This means that a single system-controlled RIB
is available for each supported address family - IPv4, IPv6 or
both. These RIBs are also the default RIBs. No user-controlled
RIBs are allowed.In addition to the mandatory instance of the "direct"
pseudo-protocol, a minimum implementation should support
configuring instance(s) of the "static" pseudo-protocol.Platforms with severely constrained resources may use
deviations for restricting the data model, e.g., limiting the
number of "static" control plane protocol instances.This appendix demonstrates how the core routing data model
can be extended to support a new control plane protocol. The YANG
module "example-rip" shown below is intended as an illustration
rather than a real definition of a data model for the RIP
routing protocol. For the sake of brevity, this module does not
obey all the guidelines specified in . See also .This section contains an example instance data tree in the
JSON encoding ,
containing both configuration and state data. The data conforms
to a data model that is defined by the following YANG library
specification :
A simple network set-up as shown in is assumed: router "A" uses static default
routes with the "ISP" router as the next-hop. IPv6 router
advertisements are configured only on the "eth1" interface and
disabled on the upstream "eth0" interface.The instance data tree could then be as follows:RFC Editor: Remove this section upon publication as an RFC.Removed "route-tag" feature.Removed next-hop classifiers.Fixed invalid when expressions in augments.In simple-next-hop, an address, outgoing interface or
both can be specified.RPC "fib-route" changed into RIB action
"active-route".The requirement that direct routes be always placed in
default RIBs.Added "next-hop-list" as a new case of the
"next-hop-options" choice.Renamed "routing protocol" to "control plane
protocol" in both the YANG modules and I-D text.Routing instances were removed.IPv6 RA parameters were moved to the
"ietf-ipv6-router-advertisements".Assignment of L3 interfaces to routing instances is now
part of interface configuration.Next-hop options in configuration were aligned with
state data.It is recommended to enclose protocol-specific
configuration in a presence container.The leaf "route-preference" was removed from the
"routing-protocol" container in both "routing" and
"routing-state".The "vrf-routing-instance" identity was added in
support of a common routing-instance type in addition to
the "default-routing-instance".Removed "enabled" switch from "routing-protocol".The container "ribs" was moved under "routing-instance"
(in both "routing" and "routing-state").Typedefs "rib-ref" and "rib-state-ref" were removed.Removed "recipient-ribs" (both state and configuration).Removed "connected-ribs" from "routing-protocol" (both
state and configuration).Configuration and state data for IPv6 RA were moved
under "if:interface" and "if:interface-state".Assignment of interfaces to routing instances now use
leaf-list rather than list (both config and state). The
opposite reference from "if:interface" to
"rt:routing-instance" was changed to a single leaf (an
interface cannot belong to multiple routing instances).Specification of a default RIB is now a simple flag
under "rib" (both config and state).Default RIBs are marked by a flag in state data.Added Acee as a co-author.Removed all traces of route filters.Removed numeric IDs of list entries in state data.Removed all next-hop cases except "simple-next-hop" and
"special-next-hop".Removed feature "multipath-routes".Augmented "ietf-interfaces" module with a leaf-list of
leafrefs pointing form state data of an interface entry to
the routing instance(s) to which the interface is
assigned.Added 'type' as the second key component of
'routing-protocol', both in configuration and state
data.The restriction of no more than one connected RIB per
address family was removed.Removed the 'id' key of routes in RIBs. This list has
no keys anymore.Remove the 'id' key from static routes and make
'destination-prefix' the only key.Added 'route-preference' as a new attribute of routes
in RIB.Added 'active' as a new attribute of routes in
RIBs.Renamed RPC operation 'active-route' to 'fib-route'.Added 'route-preference' as a new parameter of routing
protocol instances, both in configuration and state data.Renamed identity 'rt:standard-routing-instance' to
'rt:default-routing-instance'.Added next-hop lists to state data.Added two cases for specifying next-hops indirectly -
via a new RIB or a recursive list of next-hops.Reorganized next-hop in static routes.Removed all 'if-feature' statements from state data.Removed all defaults from state data.Removed default from 'cur-hop-limit' in config.Removed dependency of 'connected-ribs' on the
'multiple-ribs' feature.Removed default value of 'cur-hop-limit' in state data.Moved parts of descriptions and all references on IPv6 RA
parameters from state data to configuration.Added reference to RFC 6536 in the Security section.Wrote appendix about minimum implementation.Remove "when" statement for IPv6 router interface
state data - it was dependent on a config value that
may not be present.Extra container for the next-hop list.Names rather than numeric ids are used for referring to
list entries in state data.Numeric ids are always declared as mandatory and
unique. Their description states that they are ephemeral.Descriptions of "name" keys in state data lists
are required to be persistent.Removed "if-feature multiple-ribs;" from connected-ribs."rib-name" instead of "name" is used as the name of
leafref nodes."next-hop" instead of "nexthop" or "gateway" used
throughout, both in node names and text.Removed feature "advanced-router" and introduced two
features instead: "multiple-ribs" and "multipath-routes".Unified the keys of config and state versions of
"routing-instance" and "rib" lists.Numerical identifiers of state list entries are not keys
anymore, but they are constrained using the "unique" statement.Updated acknowledgements.Migrated address families from IANA enumerations to
identities.Terminology and node names aligned with
the I2RS RIB model: router -> routing instance, routing
table -> RIB.Introduced uint64 keys for state lists: routing-instance,
rib, route, nexthop.Described the relationship between system-controlled and
user-controlled list entries.Feature "user-defined-routing-tables" changed into "advanced-router".Made nexthop into a choice in order to allow for
nexthop-list (I2RS requirement).Added nexthop-list with entries having priorities
(backup) and weights (load balancing).Updated bibliography references.Added subtree for state data ("/routing-state").Terms "system-controlled entry" and "user-controlled
entry" defined and used.New feature "user-defined-routing-tables". Nodes that are
useful only with user-defined routing tables are now conditional.Added grouping "router-id".In routing tables, "source-protocol" attribute of routes
now reports only protocol type, and its datatype is
"identityref".Renamed "main-routing-table" to "default-routing-table".Fixed "must" expression for "connected-routing-table".Simplified "must" expression for "main-routing-table".Moved per-interface configuration of a new routing
protocol under 'routing-protocol'. This also affects the
'example-rip' module.Changed reference from RFC6021 to RFC6021bis.The contents of <get-reply> in was updated: "eth[01]" is used as
the value of "location", and "forwarding" is on for both
interfaces and both IPv4 and IPv6.The "must" expression for "main-routing-table" was
modified to avoid redundant error messages reporting address
family mismatch when "name" points to a non-existent routing
table.The default behavior for IPv6 RA prefix advertisements
was clarified.Changed type of "rt:router-id" to "ip:dotted-quad".Type of "rt:router-id" changed to "yang:dotted-quad".Fixed missing prefixes in XPath expressions.Document title changed: "Configuration" was replaced by
"Management".New typedefs "routing-table-ref" and "route-filter-ref".Double slashes "//" were removed from XPath expressions
and replaced with the single "/".Removed uniqueness requirement for "router-id".Complete data tree is now in .Changed type of "source-protocol" from "leafref" to "string".Clarified the relationship between routing protocol
instances and connected routing tables.Added a must constraint saying that a routing table
connected to the direct pseudo-protocol must not be a main
routing table.Routing tables are now global, i.e., "routing-tables" is
a child of "routing" rather than "router"."must" statement for "static-routes" changed to "when".Added "main-routing-tables" containing references to main
routing tables for each address family.Removed the defaults for "address-family" and "safi" and
made them mandatory.Removed the default for route-filter/type and made this
leaf mandatory.If there is no active route for a given destination, the
"active-route" RPC returns no output.Added "enabled" switch under "routing-protocol".Added "router-type" identity and "type" leaf under
"router".Route attribute "age" changed to "last-updated", its type
is "yang:date-and-time".The "direct" pseudo-protocol is always connected to main
routing tables.Entries in the list of connected routing tables renamed
from "routing-table" to "connected-routing-table".Added "must" constraint saying that a routing table must
not be its own recipient.Changed "error-tag" for both RPC operations from "missing
element" to "data-missing".Removed the decrementing behavior for advertised IPv6
prefix parameters "valid-lifetime" and
"preferred-lifetime".Changed the key of the static route lists from "seqno" to
"id" because the routes needn't be sorted.Added 'must' constraint saying that "preferred-lifetime"
must not be greater than "valid-lifetime".Module "iana-afn-safi" moved to I-D "iana-if-type".Removed forwarding table.RPC "get-route" changed to "active-route". Its output is
a list of routes (for multi-path routing).New RPC "route-count".For both RPCs, specification of negative responses was
added.Relaxed separation of router instances.Assignment of interfaces to router instances needn't be
disjoint.Route filters are now global.Added "allow-all-route-filter" for symmetry.Added about
interactions with "ietf-interfaces" and "ietf-ip".Added "router-id" leaf.Specified the names for IPv4/IPv6 unicast main routing
tables.Route parameter "last-modified" changed to "age".Added container "recipient-routing-tables".Added module "ietf-ipv6-unicast-routing".The example in now uses
IP addresses from blocks reserved for documentation.Direct routes appear by default in the forwarding
table.Network layer interfaces must be assigned to a router
instance. Additional interface configuration may be present.The "when" statement is only used with "augment", "must" is
used elsewhere.Additional "must" statements were added.The "route-content" grouping for IPv4 and IPv6 unicast now
includes the material from the "ietf-routing" version via
"uses rt:route-content".Explanation of symbols in the tree representation of data
model hierarchy.AFN/SAFI-independent stuff was moved to the "ietf-routing"
module.Typedefs for AFN and SAFI were placed in a separate
"iana-afn-safi" module.Names of some data nodes were changed, in particular
"routing-process" is now "router".The restriction of a single AFN/SAFI per router was
lifted.RPC operation "delete-route" was removed.Illegal XPath references from "get-route" to the datastore
were fixed.Section "Security Considerations" was written.