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OpenVPN Data Channel Offload: Unleashing Superior VPN Performance

Abstract

Welcome to the future of VPN technology with OpenVPN Data Channel Offload in the Linux kernel (ovpn-dco), available for Access Server.

OpenVPN Data Channel Offload (DCO) is a Linux kernel module that significantly improves VPN performance by moving data channel processing from user space into the kernel. By reducing context switching and leveraging kernel-level networking and multi-threading, DCO enables:

  • Higher throughput.

  • Lower latency.

  • More efficient CPU usage.

Enhancing Access Server

With OpenVPN DCO, Access Server can deliver improved performance by offloading data plane operations to the Linux kernel. This reduces overhead from kernel-to-user space transitions and allows the system to handle VPN traffic more efficiently.

DCO in Access Server 3.x

In Access Server 3.x, DCO is enabled by default.

  • The installation script automatically installs and configures DCO.

  • When using a package manager, the DCO module may still need to be installed manually.

  • Access Server 3.2.0 introduces an updated DCO implementation based on upstream Linux kernel 6.16+.

These changes improve compatibility with modern Linux kernels and align DCO with upstream OpenVPN development.

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