What P4 programming is and why it’s such a big deal for Software Defined Networking


The dawn of software defined networking (SDN) ushered in an era of disaggregation of the networking control plane from the data plane; management of the network was no longer bound to the networking hardware it ran on.

This created a market of overlay control-plane software from companies like Nicira, which was sold to VMware and is now NSX; Cisco ACI and others followed suit. But at the data plane – where network packets are actually forwarded – there has been less innovation, says IDC data center network research director Brad Casemore. Until now.

In recent years a new high level programming language for routers and switches named P4 has been developed by some of the original founders of SDN. “This is really about making the whole stack, all the way down to the silicon, programmable,” Casemore says.

What you need to know about P4

P4 is an open source programming language that lets end users dictate how networking gear operates. It controls silicon processor chips in network forwarding devices such as switches, routers and network interface cards. Whereas currently network functions are built “bottoms-up” with fixed-function switches having one way of forwarding packets, programmable networks can be controlled “top-down” to install any functionality the user wants. It’s not dissimilar to the OpenFlow open source control plane software, but is instead focused on the data plane layer.

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