Balancing on the Edge: Transport Affinity without Network State


João Taveira Araújo, Lorenzo Saino, Lennert Buytenhek, and Raul Landa, Fastly


Content delivery networks and edge peering facilities have unique operating constraints which require novel approaches to load balancing. Contrary to traditional, centralized datacenter networks, physical space is heavily constrained. This limitation drives both the need for greater efficiency, maximizing the ability to absorb denial of service attacks and flash crowds at the edge, and seamless failover, minimizing the impact of maintenance on service availability.

This paper introduces Faild, a distributed load balancer which runs on commodity hardware and achieves graceful failover without relying on network state, providing a cost-effective and scalable alternative to existing proposals. Faild allows any individual component of the edge network to be removed from service without breaking existing connections, a property which has proved instrumental in sustaining the growth of a large global edge network over the past four years. As a consequence of this operational experience, we further document unexpected protocol interactions stemming from misconfigured devices in the wild which have significant ramifications for transport protocol design.

NSDI '18 Open Access Videos Sponsored by
King Abdullah University of Science and Technology (KAUST)

Open Access Media

USENIX is committed to Open Access to the research presented at our events. Papers and proceedings are freely available to everyone once the event begins. Any video, audio, and/or slides that are posted after the event are also free and open to everyone. Support USENIX and our commitment to Open Access.

@inproceedings {211223,
author = {Joao Taveira Araujo and Lorenzo Saino and Lennert Buytenhek and Raul Landa},
title = {Balancing on the Edge: Transport Affinity without Network State},
booktitle = {15th {USENIX} Symposium on Networked Systems Design and Implementation ({NSDI} 18)},
year = {2018},
isbn = {978-1-931971-43-0},
address = {Renton, WA},
pages = {111--124},
url = {},
publisher = {{USENIX} Association},