Mastering SONiC: 6 Essential Points to Grasp for Open Networking Success

SONiC (Software for Open Networking in the Cloud) is an open-source network operating system that differs significantly from other network operating systems you’ve encountered before. Learning SONiC requires new mental preparation and skill reserves. As a new operating system that fundamentally transforms network architecture, the following key insights and abilities are what all SONiC learners should understand and master.

Linux Fundamentals Must Be Mastered

Linux is the core foundation of the SONiC network operating system. Unlike traditional network operating systems (such as IOS or Junos) that completely hide the underlying implementation, SONiC exposes the full Linux system.

From systemd service management to containerized application deployment, every layer requires direct intervention, so you need to:

• Deeply understand the Linux file system structure and quickly locate key configuration files (such as the /etc/sonic/ directory)
• Proficiently use log analysis tools (journalctl, grep) to troubleshoot various service logs in /var/log/
• Master systemd service management (systemctl start/stop/restart/enable)
• Be skilled with Docker containers (docker ps/exec/logs/inspect)
• Understand Linux network namespaces and virtual network devices

It is recommended to enhance your Linux skills before deploying SONiC through the following methods:

1. Complete a basic Linux system administrator course
2. Practice common troubleshooting in an experimental environment
3. Familiarize yourself with containerization technology basics
4. Master basic Bash script writing abilities

Understanding Containerization and Deployment

SONiC adopts a microservices architecture design, where each network function component (such as BGP, LLDP, etc.) runs in an independent Docker container. This forms a stark contrast to the monolithic architecture of traditional network operating systems.

This architecture brings three key characteristics:

1. Component isolation: Each service has its own independent log system, network namespace, and resource allocation, with faults strictly controlled within a single container.
2. Dynamic scalability: Services can be started or stopped on demand, supporting hot updates and grayscale releases.
3. Fine-grained management: Achieve component-level operations and maintenance through commands like docker exec/restart/logs.

Learning SONiC requires shifting the following mindsets:

• From “global configuration” to “component configuration”
• From “single log” to “distributed log tracing”
• From “overall restart” to “service hot update”

Mastering the Core Component Redis

SONiC uses Redis as the core data bus, achieving decoupling of configuration and state through multiple logical databases. For learning SONiC, you need to master:

Mastering Multi-DB Architecture Analysis

• CONFIG_DB: Persistent configuration (equivalent to the running-config in traditional NOS)
• STATE_DB: Real-time state collection (similar to SNMP but more structured)
• APPL_DB: Inter-process communication bus (an innovative IPC mechanism)

Mastering Key Redis Operations and Maintenance Skills

• Use redis-cli to quickly locate configuration items
• Understand the mapping relationship between YANG models and Redis schema
• Master swss (Switch State Service)

Therefore, it is recommended for new learners:

1. Start from the DB schema documentation rather than directly operating the CLI
2. Use the sonic-db-cli encapsulation tool to reduce operational risks
3. Establish a pre-validation process for DB changes

Mastering the Basics of Git Usage

When encountering problems in a production environment, the GitHub repository often provides answers faster than vendor support.

Essential survival skills to master:

Git Usage

• git blame to track a specific line of configuration
• Use git bisect to quickly locate the commit that introduced a bug
• Proficiently switch between community branches and vendor-customized branches for source-level walkthroughs

Key Modules

• swss (configuration processing pipeline)
• syncd (ASIC abstraction layer)
• orchagent (core business logic)

DevOps and Automation Mindset

Learn to use Terraform with declarative syntax to manage SONiC devices:

• Define switch resources
• Manage configuration blocks for VLAN, BGP, ACL, etc.
• State files

Learn Ansible: Batch deployment and configuration

• Use the sonic_config module to push config_db.json
• Dynamically generate configurations (Jinja2 templates + variable files)

Master configuration management (config_db.json), SONiC’s core configuration method, rather than the traditional configure terminal.

Programming Language Abilities

SONiC programming abilities directly determine your operations and maintenance.

Python

• Parse config_db.json (json.loads()/json.dumps())
• Write custom Orchagent (handle Redis DB events)
• Automated testing (pytest-sonic framework)

Bash Scripting (Quick Operations and Maintenance Tools)

• Batch operate Docker containers

Go (Cloud-Native Component Development)

• Participate in SONiC community development (such as adding new SAI interfaces)
• Write K8s CNI plugins (Calico/SRIOV integration)
• High-performance network monitoring Agent (replacing some Python scripts)

YAML/JSON (Configuration as Code)

• Ansible Playbook to define device configurations
• Terraform variable files to manage environmental differences
• K8s CRD to manage SONiC clusters

C++ (Essential for Low-Level Development)

• Modify SAI (Switch Abstraction Interface)
• Debug syncd process core logic
• Optimize ASIC driver performance