Device programmibality rest v1 00

Software-Defined Networking and Network Programmability

Mark “Mitch” Mitchiner - Solutions Architect

CCIE #3958

[email protected] 2016

Cisco Confidential 2© 2013-2014 Cisco and/or its affiliates. All rights reserved.

Evolution of an Architecture

Traditional Control Plane Architecture

Two Fundamental Architectural Issues- Box by Box Management of the System- Network Architecture as a Fully Distributed Service

Evolved Control Plane Architectures

Anticipated benefits:

• Closely aligns the control plane with the needs of applications

• Enables componentization with associated APIs

• Improves performance , enhance manageability, operations and consistency


Types of Interactions:

Bootstrap

Configure

Monitoring

Extend

What’s Evolving:

Manual -> Automated

Static -> Dynamic

Generic -> Custom

Why:

Agility

Scale

Cost

Complexity

Evolving Our Interaction with Network OS


SDN and Network Programming – Centralized Model

• OpenFlow and Open Network Foundation (ONF) are credited with starting the discussion of SDN and providing the first modern SDN control protocol

• ONF defines SDN as a decoupling of the control plane and the data plane, through the OpenFlow protocol

• OpenFlow provides:

• Standardized southbound protocol

• Robust flow/traffic control through OF primitives

• Powerful combinational pipeline model for pattern matching

• Potential challenges:

• Scale

• Availability

• Performance

• Complexity


SDN: IETF Model

Software-Defined Networking (SDN) can be defined as a new approach for network programmability

Network programmability refers to the capacity to initialize, control, change, and manage network behavior dynamically via open interfaces


How > 70% of Config Management is Done Today

Router#conf t

Enter configuration commands, one per line. End with CNTL/Z.

Router(config)#blah blah blah ?

% Unrecognized command

Router(config)#^Z

Router#wr mem

Building configuration...

[OK]

Router#

Task Oriented

Human Friendly

Easy To Replay

No Special Tools

Software Unfriendly

Subject To Change

No Common Data Model

No Error Reporting


The Evolution of Device Interaction

Traditional

Evolving ONIEiPXE

Plug n Play

PoAP

Smart InstallAuto Install

CLI

BootstrapControllers

OpenstackPuppet/Chef

RESTJSON RPCNETCONF

CLI

ConfigureI2RS

OpenFlow

OnboxPython

EEM

ExtendPush model

BGP-LS

Netflow

SNMP

Syslog

CLI

Monitor


Software defined networking (SDN) is an architecture that allows the network to more reactive to the requirements of the services and workloads placed upon it

• Hybrid approach takes advantage of hardware intelligence as well as existing feature sets within the network operating system

• Network devices can be exposed to the application layer through application programming interfaces (APIs)

• Allows an evolutionary approach to network programmability

• Over 95% of the use cases for SDN involve the centralization of the Management Plane

Model-driven Programmability – The Rise of Network Automation

Model-Driven APIs

XML JSON

Netconf Restconf

YANG Models

Network Infrastructure


Requirements of Next-Gen Config Management

Easy to Use

Separates Config and Operational Data

Lots of Tooling

Accessible Format

Error Checking

Backup/Restore Capability

Human & Machine Friendly

RFC3535


Key Protocols: NETCONF


NETCONF is an IETF Config Management Protocol

V 1.0

• RFC 3535 Background and requirements

• RFC 4741 1.0 Base NETCONF Protocol

• RFC 4742NETCONF over SSH

V 1.1

• RFC 6241 – 1.1 Base NETCONF Protocol

• RFC 6242 –NETCONF over SSH

Extensions

• RFC 5277 Notifications

• RFC 5717 Partial Locking

• RFC 6243 With defaults

• RFC 6244 NETCONF + YANG Architectural Overview

Content

Operations

Messages

Transport

Protocol Stack

http://www.rfc-editor.org/rfc/rfc3535.txt










• NMS• Script• Plugin• Cut-n-Paste

NETCONF Uses a Client-Server Model

ServerClient

SSH

Connection-Oriented

Authenticated

Reliable

Trustworthy

Secure


Clients Make Requests Using RPCs

ServerClient

<rpc message-id=“1”>

<rpc-reply message-id=“1”>

A simple Remote Procedure Call (RPC) paradigm facilitates communication between the client and the server (aka the network device).


Operations: What Clients Do to Servers


NETCONF Data Stores: Target of Operations

• Named containers that may hold an entire copy of the configuration

• Not all data stores are supported by all devices

• Running is the only mandatory data store

• Not all data stores are writable

• Check the device’s capabilities

• To make changes to a non-writeable data store, copy from a writable one

• URL is supported by IOS (for config-copy)

<running> <startup> <candidate> <URL>


NETCONF Encodes Everything In XML

<?xml version='1.0' encoding='UTF-8'?><rpc message-id="1001">

<get-config><source>

<running/></source>

</get-config></rpc>

eXtensible Markup Language • XML describes data

• <> delimit markup text (tags)

• Machine and human readable

• W3C Recommendation

• Self-descriptive


Example – Interface Configuration


NETCONF Protocol Stack Summary

• Config / Operational DataContent

• <get>, <get-config>, etcOperations

• <rpc>,<rpc-reply>Messages

• SSHTransport


NETCONF References

Tutorials: https://www.youtube.com/watch?v=Vr4kB1_6fLQhttps://www.youtube.com/watch?v=xoPZO1N-x38

Tools: Ncclient: https://github.com/leopoul/ncclient/Confd Netconf-console: http://www.tail-f.com/management-agent/

ReferencesRFC 6241 https://tools.ietf.org/html/rfc6241RFC 6242 https://tools.ietf.org/html/rfc6242

https://www.youtube.com/watch?v=Vr4kB1_6fLQ

https://www.youtube.com/watch?v=xoPZO1N-x38

https://github.com/leopoul/ncclient/


Key Technologies: Data Models & YANG


What is YANG?

• A data-modeling language for NetConfand RESTconf

• 'Yet Another Next-Generation'

• Models both configuration data and state for network platforms an XML tree format

• Can define the format used for event notifications

• Designed to be human-readable and extensible

• Standardized models are defined by the IETF NetMod working group (RFC 6020)


YANG Is A Language

module ietf-interfaces {import ietf-yang-types {

prefix yang; }container interfaces {

list interface { key "name"; leaf name {

type string;}leaf enabled {

type boolean; default "true";

}…

Self-contained top-level hierarchy of nodes

Import or define data types

Leaf nodes for simple data

Lists for sequence of entries

Containers group related nodes


The Interfaces Data Model in Tree Diagram

Source: http://www.ietf.org/rfc/rfc7223.txt


The XML Instantiation

<rpc-reply xmlns="urn:ietf:params:xml:ns:netconf:base:1.0" message-id="101"> <data>

<interfaces xmlns="urn:ietf:params:xml:ns:yang:ietf-interfaces”xmlns:ianaift="urn:ietf:params:xml:ns:yang:iana-if-type” > <interface> <name>eth0</name><type>ianaift:ethernetCsmacd</type><enabled>false</enabled>

</interface></interfaces>

</data></rpc-reply>


Where Yang Models Come From

Vendors IETF OpenConfig Other


YANG References

Tutorialshttp://www.yang-central.org/twiki/bin/view/Main/YangTutorialshttps://www.youtube.com/watch?v=33VBb6N4yOY

ToolsPyang (python) https://code.google.com/p/pyang/Commercial YANG browsers – MG-Soft, Segue Softhttp://rob.sh/post/209 (pyangbind)

ReferencesRFC 6020 (YANG) : http://tools.ietf.org/html/rfc6020RFC 7223 (Interface Model) http://www.ietf.org/rfc/rfc7223.txthttps://github.com/YangModels/yang/tree/master/experimental/openconfig (OpenConfig)https://github.com/YangModels/yang/tree/master/vendor/cisco (Cisco)

https://code.google.com/p/pyang/

http://rob.sh/post/209

http://tools.ietf.org/html/rfc6020

http://www.ietf.org/rfc/rfc7223.txt

https://github.com/YangModels/yang/tree/master/experimental/openconfig

https://github.com/YangModels/yang/tree/master/vendor/cisco


Key API: REST


REST Follows a Familiar Model

HTTP GET

HTML

Describes how data should be displayed to please human viewer

HTTP GET

JSON/XML

Describes data in a format applications can understand

{"ids":[303776224, 19449911, 607032789, 86544242, 2506725913, 17631389], "next_cursor":0, "next_cursor_str":"0", "previous_cursor":0, "previous_cursor_str":"0"}

Web Browsing REST API


What is REST?

• Stands for “REpresentational State Transfer”

• An architectural style for designing scalable networked applications

• Uses HTTP or HTTPS to transmit calls between entities

• Simple CRUD using HTTP

• Operates on resource representations, each uniquely identified by a URL

• Stateless client-server model

• Term was first used by Roy T Fielding in 2000

Author of HTTP 1.0

Alternative to Simple Object Access Protocol (SOAP) and Web Services Description Language (WSDL)


RESTful Interactions

Client Server

Client requests object state

Server returns object state

Client specifies desired state

Server returns resultant state


REST HTTP Methods (or Verbs)

Method Description

GET List the URIs in a collection, or a representation of an individual member

POST Create a new entry in a collection. The new entry's URI is assigned automatically and returned by the operation

PUT Replace an entire collection with a collection, or individual member with another. If a member doesn't exist create it

DELETE Delete an entire collection or an individual member


Why Does This Matter for Networking?

Human Readable

Software Friendly

Large Developer

Base

Client Libraries in Many

Languages


Key API: RESTCONF


RESTCONF - why?

• draft-ietf-netconf-restconf*• “RESTCONF uses HTTP operations to provide CRUD operations on

a NETCONF datastore containing YANG- defined data.”

• Allows use of familiar HTTP Tools and programming libraries

• Tap into pool of developers familiar with HTTP & REST

• Supports XML or JSON data representation

• Why REST-like?• Is Yang model based • This is actually an advantage: Schema allows API predictability and

automation vs model discovery


RESTCONF: Best of Both Worlds?

NETCONF/YANG– SSH– XML

+ JSON + HTTP(S)

RESTCONF

NETCONF REST

YANG

JSON

HTTP

“the simplicity of the HTTP protocol with the predictability and automation potential of a schema-driven API”


RESTCONF is Not A Replacement for NETCONF

• Enables Web Applications to access configuration and operational data

• A simplified transaction model

• Data can be XML or JSON

• Operations include: GET, PUT,PATCH, POST, & DELETE,

NETCONF Operations Not Supported By RESTCONF

• Config locking

• Candidate config

• Startup config

• Validate

• Confirmed commit


What makes NETCONF/YANG & RESTCONF different?

SNMP NETCONF SOAP REST RESTConf

Standard IETF IETF W3C - IETF

Resources OIDs Paths URLs URLs

Data models Defined in MIBs

YANG CoreModels

YANGModels

Data Modeling Language

SMI YANG (WSDL, not data)

Undefined, (WSDL), WADL, text…

YANG

Management Operations

SNMP NETCONF In the XML Schema, not standardized

HTTP operations

HTTP operations

Encoding BER XML XML XML, JSON,…

XML, JSON

Transport Stack

UDP SSHTCP

SSLHTTPTCP

SSLHTTPTCP

SSLHTTPTCP


Cisco Open Device Programmability


Cisco Open Device Programmability

Physical and Virtual Network Infrastructure

Open Device Programmability

ProgrammableInterfaces

OpenProtocols

Configuration Management

TrafficEngineering

Telemetry & Troubleshooting

SimplifiedDeployment

RESTconf

• IETF draft

• REST “like” interface for accessing YANG data models

• Session oriented

• Runs over HTTP(S)

• IETF standard

• Designed for network programmability

• Session and connection oriented

• Runs over SSH or SOAP

• Open source initiative

• Designed for generic client / server communications

• Session oriented

• Runs over HTTPS

Programmatic Interfaces*Interface Types

NETCONF 1.1 gRPC(IOS-XR only)

Simplified Deployment

Traffic EngineeringTelemetry Troubleshooting


* Planned for H2CY16

NETCONF 1.1

RESTconfgRPC

(IOS-XR only)

Programmable Interfaces*

Device Features

Interface BGP QoS ACL …

Data Model

Configuration

StandardDevice Specific

Operational

StandardDevice Specific

SNMP

Physical and Virtual Network Infrastructure

Programmable

Interfaces

* Planned for H2CY16

Simplified Deployment

Traffic EngineeringTelemetry Troubleshooting



Demo

Thank you.

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