This is a live document that I use to present the state of NETCONF and YANG in various contexts. I use it to inform and get conversation going, not to provide complete and final documentation of NETCONF and YANG. I update this document almost monthly, mostly with regards to industry support and working group timelines, check back!

1. A 30-minute Introduction to NETCONF and YANG
Carl Moberg <calle@tail-f.com>
twitter: @cmoberg
Last updated 2011-11-18

2. Document Introduction
• This is a live documentation that I use to present the state
of NETCONF and YANG in various contexts
• I use it to inform and get conversation going, not to provide
complete and final documentation of NETCONF and YANG
• I update this document roughly quarterly, mostly with
regards to industry support and working group
timelines, check back or get in touch!
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3. Some Background
• NETCONF is an IETF configuration management protocol
and YANG is its data modeling language
• In response to SNMP/SMI shortcomings for managing
configuration e.g.:
– Lack of support for simple things like backup-and-restore of element
configuration
– No concept of transactions (single- or multibox)
– Many inherent limitations in SMI (e.g. label length)
• Lots of background text in RFC 3535 Overview of the 2002
IAB Network Management Workshop
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4. NETCONF and YANG Brief Timeline
NETCONF YANG
• 2001 • 2007
IETF Meeting with poll of YANG design team proposal
SNMP SET usage
• Apr 2008
• June 2002
NETMOD WG established
IAB Network Mgmt Workshop
• Oct 2010
• May 2003
YANG RFC 6020 published
NETCONF WG established
• Dec 2006
NETCONF core RFCs
published
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5. So What is NETCONF?
• NETCONF is an IETF network management protocol
designed to support management of
configuration, including:
– Distinction between configuration and state data
– Multiple configuration data stores (candidate, running, startup)
– Configuration change validations
– Configuration change transactions
– Selective data retrieval with filtering
– Streaming and playback of event notifications
– Extensible remote procedure call mechanism
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6. Ok, So What is YANG
• YANG is a data modeling language designed to write data
models for the NETCONF protocol. It provides the following
features:
– Human readable, and easy to learn representation
– Hierarchical configuration data models
– Reusable types and groupings (structured types)
– Extensibility through augmentation mechanisms
– Supports definition of operations (RPCs)
– Formal constraints for configuration validation
– Data modularity through modules and sub-modules
– Well defined versioning rules
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7. NETCONF Layering Model
Layer NETCONF
Content Configuration Data
Operations <get> <get-config> <notification>
<rpc>
RPC
<rpc-reply>
Transport
SSH, SSL, BEEP, etc
Protocol
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8. Basic NETCONF Operations
• Get configuration <get-config>
– Retrieve all or part of a specified configuration from a named data store
• Get all information <get>
– Retrieve running configuration and device state information
• Edit configuration <edit-config>
– Loads all or part of a specified configuration to the specified target
configuration
• Copy configuration <copy-config>
– Create or replace an entire configuration datastore with the contents of
another complete configuration datastore.
• Delete configuration <delete-config>
– Delete a configuration datastore (not applicable to running)
• Lock and unlock <lock>, <unlock>
– Short-lived lock and unlock of the configuration system of a device
• Close and kill session <close-session>, <kill-session>
– Graceful (close) or forced (kill) termination of a NETCONF session
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9. YANG Feature Highlights
• YANG definitions directly map to NETCONF (XML) content
• YANG uses a compact C and Java-like syntax with
readability is highest priority
• Data type system leverages work done for next-generation
SNMP type system accommodating XML and XSD
requirements
• YANG can be formally translated to DSDL
(RelaxNG, Schematron and DSRL) as described in RFC
6110
• There is also an informal translation to W3C XML Schema
in the pyang tool
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10. YANG Feature Highlights (cont’d)
• Organization
– Leaf, leaf-list, container, lists, grouping, choice
• Data model structure
– Module, submodule, augment, if-feature, when
• Constraints
– Must, unique, min-elements, max-elements, mandatory
• Data types
– Many built-in types, sub-typing, restrictions
• Reusable groupings
– Grouping, uses
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11. YANG Example
module acme-system {
namespace "http://acme.example.com/system";
prefix "acme”;
organization "ACME Inc.”;
contact "joe@acme.example.com";
description
"The module for entities implementing the ACME
system.”;
revision 2007-11-05 {
description "Initial revision.”;
}
container system {
leaf host-name {
type string;
description "Hostname for this system”;
}
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12. YANG Example (cont’d)
list interface {
key "name";
description "List of interfaces in the system”;
leaf name {
type string;
}
leaf type {
type string;
}
leaf mtu {
type int32;
}
}
}
}
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13. Known NETCONF Vendor Implementations
– Alaxala – Juniper Networks
• Ethernet switches • JUNOS 7.5 and later
– BATM/Telco Systems – Nexor
• T-Metro 7224 • Messaging Gateways
– BigBand – RuggedCom
• MSP2800 • RX5000 and MX5000
– Brocade – Sonus
• NetIron XMR, CES, and CER • NBS5200 Session Border Controller
• MLX Series – Taseon
• VDX (Announced, not released) • TN 320
– Cisco – Verivue
• IOS 12.4(9)T and later • MDX 9020
• IOS XE 2.1 and later
– Edgeware
• WTV-2X
– Ericsson
• SEA 20 Entries in italics is new in this version of the
– H3C presentation
• S9500E Series Routing Switches
Please Note that this list is work in
– Huawei
• AR3200/2200 Enterprise Routers
progress and feedback on accuracy and
completeness is strongly encouraged
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14. Available NETCONF Implementations
Commercial Products Open Source Projects
– Applied Informatics
• POCO NETCONF (server) – Ncclient (client)
– Centered Logic – NetconfX (client)
• NetconfX (client)
– Netconf4Android
– Oracle/GoAhead
• NETCONF MindAgent (server) (client)
– SNMP Research – netconf4j (client)
• EPIC NETCONF (server)
– netopeer (client/server)
– Tail-f Systems
• ConfD (server) – YencaP (client/server)
• NCS (client)
– Yuma (client/server)
– Velankani
• NOCVue ConfigMan
Please Note that this list is work in
– WebNMS
progress and feedback on accuracy and
• WebNMS Framework (client) completeness is strongly encouraged
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15. Available YANG Implementations
• Commercial Products • Open Source Projects
– MG Soft Corporation – jYang
– Oracle/GoAhead – libsmi
– SNMP Research – Pyang
– Tail-f Systems – yang-mode for Emacs
– Yuma
Please Note that this list is work in
progress and feedback on accuracy and
completeness is strongly encouraged
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16. Standards Organizations Activities
• IETF
– YANG models for Service
– NETCONF working group OAM PM and FM
focusing on: – To be published
• Access Control
• System Notifications
– NETMOD (YANG) working
group currently focusing on: – YANG module for CCAP: next
• Interfaces, routing and system generation cable head-end systems
data modules – Part of the Converged Cable
• SMIv2-to-YANG translation Access Platform Support
– Always updated: System Interface Specification
• http://tools.ietf.org/wg/netconf/
• http://tools.ietf.org/wg/netconf/
Please Note that this list is work in
progress and feedback on accuracy and
completeness is strongly encouraged
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17. Further Reading
• IETF NETMOD and NETCONF WG pages:
– http://trac.tools.ietf.org/wg/netconf/trac/wiki
– http://trac.tools.ietf.org/wg/netmod/trac/wiki
• NETCONF Central
– http://www.netconfcentral.org/
• YANG Central
– http://www.yang-central.org/twiki/bin/view/Main/WebHome
• Instant YANG – an Introduction
– http://www.tail-f.com/instant-yang-primer
• The NETCONF and YANG Users LinkedIn Group
– http://www.linkedin.com/groups/NETCONF-YANG-Users-3301774
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18. 18

19. Backup Slides
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20. Why not use XSD?
• XSD defines the syntax of XML instance documents,
• YANG defines the semantics of a configuration data model
and the syntax of XML
• For more in-depth reading:
– Why we need a NETCONF-Specific Modeling Language (draft-
lengyel-why-yang-00.txt)
– Comparing Approaches to NETCONF Modeling (CANMOD) BOF
(http://tools.ietf.org/agenda/71/canmod.html)
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21. A Layered Comparison
SNMP NETCONF SOAP
Data models MIBs Modules
Data Modeling SMI YANG
Language
Management SNMP NETCONF
Operations
RPC Protocol BER XML XML
Transport Stack UDP SSH SSL
BEEP HTTP
SOAP TCP
TLS
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