devnet-1152opendaylight yang model overview and tools

OpenDaylight YANG model Overview

Giles Heron – Principal Engineer

© 2015 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation ID

Why NETCONF/YANG - Informational RFC 3535• SNMP had failed

• For configuration, that is• Extensive use in fault handling and

monitoring

• CLI scripting• “Market share” 70%+

Abstract

This document provides an overview of a workshop held by the Internet Architecture Board (IAB) on Network Management. The workshop was hosted by CNRI in Reston, VA, USA from June 4 thru June 6, 2002. The goal of the workshop was to continue the important dialog started between network operators and protocol developers, and to guide the IETFs focus on future work regarding network management.

configuration


NETCONF and YANG in Context

NETCONFManager

NETCONF

YangModels

YANG ModelsYANG Models

YANG Models

YANG Models

ManagementApplications


What is a Data-Model? What is a Network Management Protocol?

• Data-Model• A data-model explicitly and precisely determines the

structure, syntax and semantics of the data…• …that is externally visible• Consistent and complete

• Protocol• Remote primitives to view and manipulate the data• Encoding of the data as defined by the data-model

Data-Model

Protocol


Confusion and Comparison

• Data-Models and information Models• Information models are for humans

• Not everything• Not always detailed and precise• Starting-point for data-model

• Protocol• Confusion between domain-specific network management

protocols and general RPC mechanisms• NETCONF vs. CORBA, SOAP, REST, …

Data-Model MIB Modules YANG Modules

ProtocolThe SNMP ProtocolNETCONF


What is YANG?• YANG – Yet Another Next-Generation...

• ... Communication Protocol?• ... Messaging Bus?• ... Management Information Definition Language!

• Purpose• Define management information for Netconf...• ... Original focus on configuration information, but not restricted to it• ... Can be separated from Netconf

(not a goal of the specification, but an important aspect)


YANG and XML• YANG assumes an XML encoding of instantiated information

• Defines XML rendering rules• Relies on XML encoding for certain advanced features (e.g. expression of constraints

using Xpath)• Facilitates describing XML document hierarchies• Nicely aligned with NETCONF

• YANG itself is not XML• Emphasis on readability

• Familiar structure to C/C++ or Java programmers• XML notation exists: YIN (Yang-Independent Notation)

• Semantic equivalence • Syntactic conversions YANG <-> YIN

• Alternative encodings defined (e.g. JSON for RESTconf)


YANG compared to SNMPDefinition language:

YANG

Information model:YANG modules

Instantiated data:XML

Transport:Netconf

Definition language:SMIv2

Information model:MIB modules

Instantiated data:ASN.1 BER

Transport: SNMP

“Content”

“Payload”

“Framework”

Compare SNMP

Import conversion rules exist(MIBs YANG)

“instant content”

Ability to express hierarchy(compare MIBs: flat + tables)Richer conditions, constraints

Facilities for easier reuseRPC/Action support

Human readabilityDynamic extensibility

B2B, Web toolkits

Bulk vs only incremental ops(manipulation of config files,

e.g. edit-config)Transaction support

Configuration vs monitoringor possibly other(no inherent dependency but will require different bindings)


YANG in the context of Netconf

Transport

RemoteOperations

MgmtServices

Mgmt info(payload)

Mgmt info(definition)

XML-encoded content

YANG modules

Netconf operations<edit-config>, <get-config>, <get>

Netconf RPC<rpc>, <rpc-reply>

TLS, SSH

Manager (client)

XML content

per YANG

ConceptualData Store

Agent(server)


YANG

• Data modeling language• Configuration data• State data

• Tree structure

• Data and Types

acme-box module

properties container

interfaces container

name: string, config

name: string, config

interface: list, key = name

oper-state: enum, config


RESTCONF• ReSTful protocol to access YANG defined data

• Remote State Transfer, i.e. server maintains no session state

• HTTL URLs reflect data hierarchy in a YANG-modelled datastore

RESTCONF Netconf

GET <get-config>, <get>

POST <edit-config> (“create”)

PUT <edit-config> (“replace”)

PATCH <edit-config> (“merge”)

DELETE <edit-config> (“delete”)

OPTIONS (discover supported operations)

HEAD (get without body)


Resource URI Map/restconf /config /<top-level-data-nodes> (configuration data) /operational /<top-level-data-nodes> (operational data) /modules /module /name /revision /namespace /feature /deviation /operations /<custom protocol operations> /streams /stream /name /description /replay-support /replay-log-creation-time /events /version (field)

Event streams, subscribe using “get”,

can specify filters

Meta-information:Capabilities etc

Meta-information:Supported RPCs

YANG-defined

data


ODL

Transport

RemoteOperations

MgmtServices

Mgmt info(encoding)

Mgmt info(definition)

XML-encoded content

YANG modules

NETCONF operations

XMLRPC

TLS,SSH

JSONJAVA DTO

I2RS

?

HTTP

RESTCONF

TCP

YANG - NETCONF, RESTCONF, I2RS & IDL


Controller

YANG IDL – OpenDaylight MD-SAL

MD-SAL

DOM BrokerBA-BI Connector

Mapping Service

Codec Registry

Schema Service

Codec Generator

Binding-Aware Broker Data Store

Binding-Aware to Binding-Independent Data Translation

Binding-Aware PluginBinding-Independent

Plugin/Client (NETCONF/RESTCONF)

Forwarding Rules Manager, Stats Manager, BGP-LS/PCEP

RESTCONF Clients

Internal Clients

YANG Models


Mounting Remote DatastoresOpenDaylight Controller Config

MD-SAL

NETCONF

NETCONF

• Mounted under e.g. http://localhost:8181/restconf/config/opendaylight-inventory:nodes/node/controller-config

• Data can be accessed using …/yang-ext:mount/…

• …/yang-ext:mount/config:modules is used to configure the various plug-ins

Config Store

RESTCONF


Mounting Remote DatastoresOpenDaylight NETCONF Node “Discovery”

MD-SAL

NETCONF

RESTCONF

Node Inventory

• Nodes added by POSTing to config:modules

• ODL connects to each node

• ODL learns capabilities (YANG modules) and stores to model cache• Cache at ~/cache/schema. Filenames of form [email protected].

Model Cache

XR1 XR2 OpenWRT


Mounting Remote DatastoresOpenDaylight NETCONF Node Configuration

MD-SAL

NETCONF

RESTCONF

Node Inventory

• Nodes configured by POSTing or PUTting to e.g.:• http://localhost:8181/restconf/config/o

pendaylight-inventory:nodes/node/XR2/yang-ext:mount/Cisco-IOS-XR-ifmgr-cfg:interface-configurations/interface-configuration/act/Loopback0/

• Can retrieve config (or operational stats) using GET

Model Cache

XR1 XR2 OpenWRT

http://localhost:8181/restconf/config/opendaylight-inventory:nodes/node/XR2/yang-ext:mount/




devnet-1152opendaylight yang model overview and tools

Technology

xml yang

yang information model

datamodel datamodel

datamodel protocol confusion

data encoding

snmp protocol netconf

comparison datamodels

smiv2 information model