Brussels / 30 & 31 January 2016


Snabb Switch: Riding the HPC wave to simpler, better network appliances

An experience report with a production-ready lightweight 4-over-6 implementation in Snabb

Driven by the needs of scientific computing, rapid rises in memory bandwidth have made it possible to implement high-performance network functions in a radically simpler way. Snabb Switch rides this wave, bypassing the kernel to process network packets in terse Lua, leaving the programmer free to focus on the essence of their problem. This talk presents our experiences delivering a carrier-grade implementation of "lightweight 4 over 6", an IPv4-as-a-service architecture that tunnels access to the IPv4 internet through specialized Snabb appliances.

We report on our recent experience implementing a carrier-grade virtualized network function, with observations on what it is like to build real-world, high-performance Snabb applications. (and kernel bypass). Each instance runs at essentially line speed on two ten-gigabit Ethernet cards.

Lightweight 4-over-6 (lw4o6) defines an IPv4-as-a-service architecture that allows ISPs to internally operate an IPv6-only network, tunneling IPv4 connections between lw4o6-aware endpoints installed at the customer's site (e.g. in OpenWRT) and an internet-facing "lwAFTR". Lw4o6 was specified in 2015 as RFC 7596 and has the architectural advantage that the carrier-side lwAFTR only needs per-customer state, not per-flow state. An lw4o6 system can also be configured to share IPv4 addresses between multiple customers as part of an IPv4 exhaustion strategy. It allows IPv4 networks to interoperate smoothly, while a carrier between them runs a pure-IPv6 network.

Igalia has built an open source "lwAFTR" implementation that is ready to deploy in production. We describe the joys of hacking with Snabb, giving a quick intro to Snabb, modern x86, and lw4o6 along the way.


Katerina Barone-Adesi