Did you know that FreeBSD has more than one TCP stack and that TCP stacks are pluggable at run time? Since FreeBSD 12, FreeBSD has support pluggable TCP stacks, and today we will look at the RACK TCP Stack. The FreeBSD RACK stack takes this pluggable TCP feature to an extreme: rather than just swapping the congestion control algorithm, FreeBSD now supports dynamically loading and an entirely separate TCP stack. With the RACK stack loaded, TCP flows can be handled either by the default FreeBSD TCP stack or by the RACK stack.
While new protocols are constantly being developed, the venerable Transmission Control Protocol (TCP) still accounts for most global traffic. The FreeBSD kernel TCP stack offers a lot of opportunities to tweak different performance features. The options it includes allow a lot of flexibility in the configuration of machines without having to do custom kernel builds.
Find out how to make use of the Initial Window, what the TCP Segment OffLoad is, and how to use TCP Buffer Tuning to your advantage.
Network performance is one of the most complex topics to analyse and understand. FreeBSD has a full set of debugging features, and the network stack reports a ton of information. So much that it can be hard to figure out what is relevant and what is not. In this article, we define performance, look at how to measure what is available and how to get the system to report what it is managing to do.
VNET virtual network stacks are a powerful network stack isolation technology that gives FreeBSD jails super powers. Follow our guide to use VLANs on FreeBSD, combine VLANs and VNETs and use VLANs with VNET Jails. Learn useful tricks with many exemplifying instances.
FreeBSD Jails – a well-known feature that has become core to many excellent tools on FreeBSD such as the Poudriere package builder. Jails offer process and file system isolation, but for a long time they did not offer very satisfying network isolation. Learn how to isolate networks, how to test potentially hazardous firewall changes and how to do proper jail networking.
Learn how to build better FreeBSD networks with Dummynet. Dummynet is the FreeBSD traffic shaper, packet scheduler, and network emulator. It allows you to emulate a whole set of network environments in a straight forward way, it has the ability to model delay, packet loss, and can act as a traffic shaper and policer. Follow our guide to learn how!