Network Automation

Question 1

Disadvantages of Manual Configuration of Network Hardware Using CLIs

Answer 1

• Lots of Typing
• Prone to Errors
• Inconsistencies
• Infeasible for large networks; scaling can be slow
• Multi-vendor Environments with Different Syntaxes

Question 2

Python Scripts for Configuration of Network Hardware

Answer 2

• Automates set up
• Code can easily be reused
• One scripts won’t account for different syntaxes

Question 3

Phases of Automation

Answer 3

Provisioning: Initial configuration of new hardware. Automated through
- Plugging in a console cable and running a script
- Detecting DHCP requests and firing automatic network configuration

Configuration Management: Ensures configurations remain constant

Lifecycle Management: Data collection, monitoring, application of patches/updates

Question 4

Ansible

Answer 4

Open-source Automation Tool
- Agentless: No client software to be installed on nodes, it runs commands over SSH
- Playbooks: Define tasks in YML
- Idempotent: Changes only made if necessary, only runs necessary commands, wont update device with correct config
- Push-based Model: Devices cannot request config, Ansible must SSH and provide it

Question 5

Ansible Components

Answer 5

Inventory: A list of managed nodes
Playbooks: YAML files that define tasks to be executed on managed nodes
Roles: Reusable units of tasks and configs shareable across multiple playbooks
Modules: Predefined units of code that perform specific tasks. Modules exist for vendor specific devices

Question 6

Playbooks Version Control

Answer 6

Provides change history of network configuration
Allows for auditing

Question 7

Intent-based Automation

Answer 7

Defines high-level network policies and behaviours using intent.
Translates business intent to realisable configuration
- Automates provisioning, optimisation and troubleshooting

Question 8

NETCONF

Answer 8

Protocol for managing network devices through programmatic interface
- Uses SSH

Question 9

YANG

Answer 9

Modelling language that describes network objects and configurations in an XML tree format

Question 10

RESTCONFIG

Answer 10

A programmatic interface for accessing data defined in YANG using concept defined in NETCONF
- HTTP based method for switch configuration using data from YANG