LibreQoS is an application that allows you to apply fq_codel traffic shaping to hundreds of customers. <ahref="https://www.bufferbloat.net/projects/codel/wiki/">Fq_codel</a> is a Free and Open Source Active Queue Management algorithm that reduces bufferbloat, and can improve the quality of customer connections significantly. LibreQoS works with both IPv4 and IPv6. It apples hundreds of filter rules to direct customer traffic through individual fq_codel instances within an <ahref="https://linux.die.net/man/8/tc-htb">HTB</a> (HTB+fq_codel). By utilizing <ahref="https://tldp.org/HOWTO/Adv-Routing-HOWTO/lartc.adv-filter.hashing.html">hashing filters</a>, thousands of rules can be applied with minimal impact on traffic throughput or CPU use. This is alpha software, please do not deploy in production without thorough testing.
Fq_codel distinguishes interactive flows of traffic (web browsing, audio streaming, VoIP, gaming) from bulk traffic (streaming video services, software updates). Interactive flows are prioritized to optimize their performance, while bulk traffic gets steady throughput and variable latency. The general reduction of connection latency offered by fq_codel is highly beneficial to end-users.
>“FQ_Codel provides great isolation... if you've got low-rate videoconferencing and low rate web traffic they never get dropped. A lot of issues with IW10 go away, because all the other traffic sees is the front of the queue. You don't know how big its window is, but you don't care because you are not affected by it. FQ_Codel increases utilization across your entire networking fabric, especially for bidirectional traffic... If we're sticking code into boxes to deploy codel, don't do that. Deploy fq_codel. It's just an across the board win.”
* Linux tc hash tables can only handle ~4000 rules each. This limits total possible clients to 2000 single-protocol clients (IPv4 only / IPv6 only) or 1000 dual stack clients. Eventually we will rework the code to allow for more clients by linking more hash tables.
* One management network interface, completely seperate from the traffic shaping interface NIC. Can be NATed behind motherboard Gigabit Ethernet, that's fine.
* Network interface NIC supporting two virtual interfaces for traffic shaping (in/out), preferably SFP+ capable
*<ahref="https://www.fs.com/products/75600.html">Intel X710</a> recommended for anything over 1Gbps.
On ProxMox VMs you need to do <ahref="https://www.reddit.com/r/Proxmox/comments/asakcb/problem_with_ram_cache/">some tweaks</a> to allow freed up memory to be reclaimed by the hypervisor.
Performance can greatly benefit from enabling certrain hardware offloading inside the guest VM. If you're using a system that uses Netplan (e.g. Ubuntu) to configure the network then you can use a Netplan post-up script to configure offloading. You create a script in the following directory with a name prefixed by a number to indicate load order e.g. /usr/lib/networkd-dispatcher/routable.d/10-enable-offloading - which is executable and owned by root. e.g.
Thank you to the hundreds of contributors to the fq_codel and cake projects, especially Dave Taht. Thank you to Phil Sutter, Bert Hubert, Gregory Maxwell, Remco van Mook, Martijn van Oosterhout, Paul B Schroeder, and Jasper Spaans for contributing to the guides and documentation listed below.
