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Santiago Álvarez
March 2017
YANG Development Kit (YDK)
Simplifying Network Automation Using Python Model-Driven APIs
@111pontes
@111pontes
• Speed and scale demand software automation and data analytics
• Rapid innovation as competitive advantage
• One network operator per 1000s / 10000s of complex network devices
Motivations for Network Programmability
Encoding XML JSON GPB
Protocol NETCONF gRPCRESTCONF
Model-Driven Programmability Stack
Models
APIs
Apps
Model-Driven APIs
YANG Development Kit (YDK)
YANG Models
(native, open)
App1 App2 App3
SSH HTTPTransport
Model-Driven
Configuration
Model-Driven
Telemetry
• Model based, structured, computer friendly
• Multiple model types (native, common, OpenConfig, IETF, etc.)
• Models decoupled from transport, protocol and encoding
• Choice of transport, protocol and encoding
• Model-driven APIs for abstraction and simplification
• Wide standard support while leveraging open source
Benefits of Model-Driven Programmability
• Model structures data (config, operational and RPC/actions) as a tree
• Models files are self-documented and ship with devices
• Cisco IOS XR supports ~250 YANG models (native and OpenConfig) in release 6.1.2
• OpenConfig support includes BGP, routing policy, interfaces, MPLS, telemetry and VLAN
• Native models provide most coverage
• OpenConfig models are mapped to native models
XR Data Models
Native / Common OpenConfig / IETF
• Modeling language for network devices
• Main node types
• Leaf – node with name and value of certain type (no children)
• Leaf list – sequence of leafs
• Container – groups nodes and has no value
• List – Sequence of records with key leafs
• Augmentations extend a model
• Deviations specify divergence from model
YANG
Leaf
Node without a value
Node with a value
Leaf list
Container List
key
YANG Model Example
container community-sets {description “Container for community sets";list community-set {
key community-set-name;description "Definitions for community sets";leaf community-set-name {
type string;description "name of the community set";
}leaf-list community-member {
type string {pattern '([0-9]+:[0-9]+)';
}description "members of the community set";
}}
}
community-setscommunity-set C-SET165172:1,65172:2,65172:3
!community-set C-SET1065172:10,65172:20,65172:30
!!
YANG CLI
Model Data Example
<community-sets><community-set>
<community-set-name>C-SET1</community-set-name><community-member>65172:1</community-member><community-member>65172:2</community-member><community-member>65172:3</community-member>
</community-set><community-set>
<community-set-name>C-SET10</community-set-name><community-member>65172:10</community-member><community-member>65172:20</community-member><community-member>65172:30</community-member>
</community-set></community-sets>
community-setscommunity-set C-SET165172:1,65172:2,65172:3
!community-set C-SET1065172:10,65172:20,65172:30
!!
XML CLI
• Simplify app development
• Abstract protocol, transport, encoding, modeling language
• API generated from YANG model
• One-to-one correspondence between model and class hierarchy
• Rich data validation
• Multi-language (Python, C++, Ruby, Go, etc.)
Model-Driven APIs
9
YANG ModelClass Hierarchy
(Python, C++, Ruby, Go)
Generation of Model-Driven APIs Using YANG Development Kit (YDK)
YAN
G
YANG
YANG
Data
Models
(YANG)
API
Generator
DocsPython
C++
: :
Ruby
go
Docs
Docs
Docs
C♯ Docs
YDK-gen
YDK-Py
YDK
YDK-Cpp
• Client will automatically perform local validation based on model constraints
• Check between config (read-write) and state (read-only)
• Type check (enum, string, etc.)
• Value check (range, pattern, etc.)
• Semantic check (key uniqueness/presence, mandatory leafs, etc.)
• Model deviation check (unsupported leafs, etc.)
YDK Client-Side Validation
Application
(client)
Device
(server)
YDK API Structure
Models(BGP, IS-IS, etc)
Services(CRUD, NETCONF, Codec, Executor, etc.)
Providers(NETCONF, Codec, etc.)
• Models group Python APIs created for each YANG model
• Services perform operations on model objects (interface)
• Providers implement services (implementation)
ydk.services
YDK-Py 0.5.0 Package Structure (Bundles)
ydk.models.cisco_ios_xr
ydk.providers
ydk.types
ydk.errors
ydk.models.openconfig
ydk.models.ietf
Cisco IOS XR
Core
OpenConfig
IETF
# Cisco YDK-Py OC-BGP “Hello world”from ydk.services import CRUDServicefrom ydk.providers import NetconfServiceProviderfrom ydk.models.openconfig import openconfig_bgp as oc-bgp
if __name__ == "__main__":provider = NetconfServiceProvider(address=10.0.0.1,
port=830,username=“admin”,password=“admin”,protocol=“ssh”)
crud = CRUDService() # create CRUD servicebgp = oc_bgp.Bgp() # create oc-bgp objectbgp.global_.config.as_ = 65000 # set local AS numbercrud.create(provider, bgp) # create on NETCONF deviceprovider.close()exit()
# End of script
A YDK-Py “Hello World” Using OC-BGP
module: openconfig-bgp+--rw bgp!
+--rw global| +--rw config| | +--rw as| | +--rw router-id? | +--ro state| | +--ro as| | +--ro router-id? | | +--ro total-paths? | | +--ro total-prefixes?
...
CRUD service
NETCONF provider
NETCONF service
Codec service
deviations
Service improvements
Better error handling
Bundles
(core, XR, OC, IETF)
Releases
C++ support
Bundle updates
0.3.0
Mar 2016
0.4.0
Apr 2016
0.4.1
May 2016
0.4.2
Jun 2016
0.5.0
Aug 2016
https://github.com/CiscoDevNet/ydk-gen/releases
Python 3
Bundle
updates
0.5.1
Oct 2016
0.5.2
Dec 2016
0.5.3
Jan 2017
RESTCONF
OpenDaylight
• Additional providers (e.g. Google RPC, Cisco NSO)
• Additional services (e.g. GNMI)
• Additional languages (e.g. Go, Ruby, Java)
• Additional encodings (e.g. GPB)
• Telemetry support
• Model-mapping support
Future Work Items
Accessing YDK-Py
Native Virtual Cloud
Install Python
Install YDK
Install Vagrant
Install Virtualbox
Download ydk-py-samplesYANG Development Kit Sandbox
GitHub
• YDK Python API – YDK-Py (https://git.io/vaWsg)
• YDK-Py sample apps (https://git.io/vaw1U)
• YDK C++ API – YDK-Cpp (https://git.io/v1Cst) - alpha
• YDK-Cpp sample apps (https://git.io/v14Qh)
• YDK Generator – YDK-gen (https://git.io/vaw1M)
YDK Documentation
• YDK-Py docs (http://ydk.cisco.com/py/docs)
• YDK-Cpp docs (http://ydk.cisco.com/cpp/docs)
Resources (cont.)
18
YDK Portal
• YDK at DevNet (https://goo.gl/Wqwp3C)
YDK Sandboxes
• Ubuntu YDK-Py Vagrant box (https://git.io/vaw1U)
• Ubuntu YDK-Cpp Vagrant box (https://git.io/v14Qh) – coming soon
YDK Support
• Cisco support community (https://communities.cisco.com/community/developer/ydk)
Resources (cont.)
19
Conferences
• NANOG 68: Ok, We Got YANG Data Models. Now What? (http://youtu.be/2oqkiZ83vAA )
• LinuxCon NA 2016: Simplifying Network Programmability Using Model-Driven APIs (https://goo.gl/W6tH2X)
Resources (cont.)
20
Demo
dCLoud Sandbox
R2R1
Out-of-band
network
lo0
172.16.255.1/32
g0/0/0/0
172.16.1.0/31
lo0
172.16.255.2/32
IS-IS L2 (Area 49.0001)
198.18.1.254/24
198.18.1.12/24
g0/0/0/0
172.16.1.1/31
198.18.1.11/24
NETCONF NETCONF
Controller
YDK
Backup
• Install command line tools – xcode-select --install
• Install homebrew – http://brew.sh
• Install Python/PIP – brew install python
• Install YDK dependencies – brew install pkg-config libssh xml2 curl pcre
• Clone YDK-Py – git clone https://github.com/CiscoDevNet/ydk-py.git
Preparing for Manual Installation of YDK-Py(MacOS)
Ubuntu (debian-based)
• Install Python/PIP extensions – sudo apt-get install python-pip python-lxmlpython-dev
• Install YDK dependencies – sudo apt-get install zlib1g-dev libxml2-dev libxslt1-dev
• Clone YDK-Py – git clone https://github.com/CiscoDevNet/ydk-py.git
Centos (Fedora-based)
• Install Python/PIP extensions – sudo yum install python-pip python-devel
• Install YDK dependencies – sudo yum install epel-release libxml2-devel libxslt-devel libcurl-devel libtool
• Clone YDK-Py – git clone https://github.com/CiscoDevNet/ydk-py.git
Preparing for Manual Installation of YDK-Py(Linux)
• Install Git – https://git-scm.com/download/win
• Install Python :https://www.python.org/downloads/windows/
• Add Python to PATH – C:\Python27\;C:\Python27\Scripts\
• Download PIP install script – https://bootstrap.pypa.io/get-pip.py
• Install PIP – python get-pip.py
• Install Microsoft Visual C++ Compiler for Python - https://goo.gl/ujGcY0
• Clone YDK-Py – git clone https://github.com/CiscoDevNet/ydk-py.git
Preparing for Manual Installation of YDK-Py(Windows)
• Clone YDK-Py –
git clone https://github.com/CiscoDevNet/ydk-py.git
• Install YDK core package
cd core
python setup.py sdist
pip install dist/ydk*.gz
• Install IETF bundle
cd ../ietf
python setup.py sdist
pip install dist/ydk*.gz
• Install OpenConfig bundle
cd ../openconfig
python setup.py sdist
pip install dist/ydk*.gz
• Install Cisco-IOS-XR bundle
cd ../cisco-ios-xr
python setup.py sdist
pip install dist/ydk*.gz
Installing YDK
