LibreQoS 2.0: QoS and Bufferbloat for networks

LibreQoS 2.0: Open Platform for QoS and Combating Bufferbloat

LibreQoS 2.0 is an open platform for implementing Quality of Service (QoS) in networks. It distributes bandwidth among users, minimizing Bufferbloat effects from intermediate packet buffering. The code in C, Rust, JavaScript, and Python is available on GitHub under the GNU GPL v2.0 license. The platform deploys on a server between the provider's edge router and the local network's core router.

The system optimizes traffic for ISPs and private network admins, maintaining low latency and prioritizing flows. Support for interactive apps, gaming, VoIP, video calls, and online learning holds up even under peak loads from torrents or multi-stream 4K video downloads.

Technical Foundation

LibreQoS uses CAKE (Common Applications Kept Enhanced) for queue management and fq_codel (Fair Queuing Controlled Delay) for packet scheduling. eBPF and XDP handle processing at the network driver level with direct access to DMA buffers.

CAKE simplifies queue hierarchies, maximizing throughput and minimizing latency on slow links and low-end hardware. It caps per-user peak speeds but ensures fair resource distribution and stable RTT (round-trip time).

RTT monitoring ties to users, access points, and sites. The web interface visualizes traffic, load, latency, and active users. It supports hierarchical shaping schemes and integration with UISP and Splynx.

New Features in Version 2.0

Version 2.0 focuses on diagnostics, visualization, and integrations. Key improvements:

• Enhanced web interface: new reports and charts for troubleshooting.
• Tree view: displays hierarchical network topology with node details.
• Diagnostic tools: queue analysis, traffic flow breakdowns, Sankey diagrams, TCP retransmit and RTT monitoring.
• New visualizations: traffic maps and ASN (autonomous systems) analysis.
• Integration with CRM/NMS systems: UISP, Splynx, Netzur, VISP, WISPGate, Powercode, Sonar.
• Improved shaping: TreeGuard and StormGuard for overload protection.
• Scheduler monitoring with alerts for critical events.

These changes simplify deployment in production networks of medium and large scale.

Real-World Applications

In ISP networks, LibreQoS eliminates VoIP jitter during simultaneous downloads. For enterprise networks, it prioritizes traffic for remote access and video conferences. Admins can set shaping policies by topology, integrating with existing NMS.

Example: In a network with 100+ users on a 1 Gbps uplink, CAKE + fq_codel drops RTT from 100+ ms to <20 ms under load, keeping games and VoIP responsive.

Key Takeaways

• LibreQoS 2.0 boosts diagnostics via the web interface with Tree view, Sankey diagrams, and ASN analysis.
• Integration with UISP, Splynx, and other CRM/NMS simplifies client and topology management.
• CAKE and fq_codel with eBPF/XDP deliver low latency without sacrificing throughput.
• TreeGuard and StormGuard prevent queue overloads.
• Retransmit and RTT monitoring spots bottlenecks in real time.

— Editorial Team