cloudparts

SONiC

Software for Open Networking in the Cloud: a Linux-based network operating system for data centre switches, built by Microsoft for Azure, that runs on hardware from many vendors through a common chip interface.

SONiC Foundation project
What it is
Software-defined networking
Type
Open source
Made by
SONiC Foundation (Linux Foundation), created at Microsoft
Foundation
SONiC Foundation, joined April 2022. Part of the Linux Foundation
License
Apache 2.0
Facts checked
28 October 2026
Website Source code

What it is

A data centre switch is a forwarding chip (an ASIC) plus software that decides what to program into it. Traditionally both came from one vendor. SONiC is that software as open source, a network operating system based on Linux that runs on switches from many vendors and chips. It reaches the hardware through the Switch Abstraction Interface (SAI), an API for controlling forwarding chips in a vendor-independent way, which chip makers implement in their own SDKs. The build tree has platform support for Broadcom, Marvell, NVIDIA (Mellanox), Cisco, Centec and others, plus a virtual switch for testing.

Inside, each function runs in its own Docker container, and they share state through a Redis database rather than calling each other. CONFIG_DB holds configuration such as ports, VLANs and BGP neighbours, loaded from /etc/sonic/config_db.json at boot; APPL_DB holds what applications want, such as routes; ASIC_DB holds the same state in a form ready for the chip. When BGP, run by FRR in the bgp container, learns a route, fpmsyncd writes it to APPL_DB, orchagent in the Switch State Service (swss) translates it into ASIC_DB entries, and syncd calls the SAI to program the chip. Other containers run link aggregation (teamd), LLDP, SNMP and platform monitoring, so one can be restarted or upgraded without touching the rest.

SONiC is cut twice a year, in May and November, as branches named after year and month; 202605 is the latest. In October 2026 Network World cited Gartner’s estimate that about 2,500 organisations run SONiC in production, roughly a third of them enterprises, and 650 Group’s forecast of more than $5 billion in SONiC-based data centre switching revenue in 2026, driven largely by AI clusters. It has been hosted at the Linux Foundation since April 2022, under the SONiC Foundation.

Why teams pick it

  • One operating system across switches from many vendors and chip makers, so automation, tooling and skills carry over
  • Proven at hyperscale: built for and run in Azure’s data centres, and the basis of commercial distributions from switch vendors
  • Modular containers and a Redis state database make it easy to inspect, extend and restart one function at a time
  • Vendor-neutral governance at the Linux Foundation, with an Apache 2.0 licence and backing from Microsoft, Google, NVIDIA, Broadcom, Cisco and Arista

Watch out for

  • Needs network engineers comfortable with Linux, containers and automation; Dell’Oro says operating it requires a specialised skill set
  • Hardware support depends on each chip vendor’s SAI implementation and each switch’s platform drivers, so check that your exact model is supported
  • Shaped by hyperscale cloud and AI data centres: the roadmap centres on their fabrics, not on campus or branch networks
  • Community releases are source branches and images without support; for that, enterprises turn to the distributions that switch vendors increasingly offer

Alternatives

What all software-defined networking have in common →Compare side by side →
DPDK (Data Plane Development Kit)Open sourceC libraries and drivers for processing packets in user space at line rate: applications take NICs away from the kernel and poll them from dedicated CPU cores, with no interrupts or system calls per packet.FRRouting (FRR)Open sourceAn open-source IP routing suite for Linux and BSD: BGP, OSPF, IS-IS, PIM, BFD and other protocols as separate daemons that install routes into the kernel, used in switch operating systems, routers and Kubernetes clusters.Open vSwitchOpen sourceA programmable software switch for hypervisors and container hosts: it connects VMs and containers to each other and to tunnels across the physical network, and forwards packets by OpenFlow rules that a controller can change.OpenDaylightOpen sourceAn open-source SDN controller in Java: it models networks and devices in YANG, talks to them over NETCONF, BGP, PCEP, OpenFlow, gNMI and more, and exposes it all as a RESTCONF API.OVN (Open Virtual Network)Open sourceA control plane for virtual networks built on Open vSwitch: you describe logical switches, routers, ACLs, NAT and load balancers, and it programs the OVS on every host to implement them.P4Open sourceA programming language for the data plane: it describes which headers a switch, NIC or software switch parses and which match-action tables it applies, so packet processing can be changed by recompiling instead of waiting for new chips.

How it fits with other technologies

Part of /etc/sonic/config_db.json: a 40G port and a BGP neighbour · json

{
  "PORT": {
    "Ethernet0": {
      "index": "0",
      "lanes": "101,102",
      "description": "fortyGigE1/1/1",
      "mtu": "9100",
      "alias": "fortyGigE1/1/1",
      "speed": "40000"
    }
  },
  "BGP_NEIGHBOR": {
    "10.0.0.57": {
      "name": "ARISTA01T1",
      "local_addr": "10.0.0.56",
      "asn": "64600",
      "holdtime": "10",
      "keepalive": "3"
    }
  }
}

See it in a real stack

No architecture uses SONiC yet. Drop it into the playground and wire it up yourself.Open playground →
Where it came from2015–2026

Microsoft wanted the software on Azure’s switches to stop depending on who made the hardware, so that it could choose hardware freely and change software at its own pace. Its first step was SAI, a common API to switch chips, which the Open Compute Project (OCP) accepted from Microsoft in July 2015. On March 9, 2016, at the OCP summit, Microsoft open-sourced SONiC, the Linux-based switch software built on SAI, with contributions from Arista, Broadcom, Dell and Mellanox, and proposed it for OCP.

SONiC spread from Azure to other cloud providers and to switch vendors, who began selling it on their own hardware. By 2022 it ran on more than 100 different switches. On April 14, 2022 it moved to the Linux Foundation, which adopted a technical charter for the SONiC Foundation that day; OCP kept working on hardware and on specifications such as SAI.

AI clusters then sped up its adoption. From around 2025 the community realigned its roadmap around AI data centre workloads, adding SRv6-based load balancing, packet trimming for congestion recovery and high-frequency telemetry, and Dell’Oro expects sales of SONiC switches for AI scale-out networks to grow by more than 50% a year through 2030. New members, including Lenovo in October 2026, kept joining the foundation.

Why it’s built this way

A common interface to the chip (SAI)
Defining one API for forwarding chips let the same software run on any vendor’s hardware that implements it, so Azure could buy switches on price and features rather than software.
Containers sharing a Redis database
Putting each function in its own container and passing state through a database decouples them, so one can crash, restart or be upgraded without bringing the switch down.
Standard Linux and open-source routing
Using Linux and an existing open-source routing stack let operators reuse familiar tools and contribute fixes instead of waiting for a vendor.

Timeline

  1. 2015

    OCP accepts Microsoft’s Switch Abstraction Interface (SAI) in July

  2. 2016

    Microsoft open-sources SONiC at the OCP summit on March 9

  3. 2022

    SONiC moves to the Linux Foundation on April 14; runs on more than 100 switches

  4. 2026

    Release branch 202605; Gartner counts about 2,500 production users

Sources10 · facts checked 28 October 2026

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