Rethinking Access Networks with High Performance Virtual Software BRASes

Broadband Remote Access Servers (BRASes) play a crucial role in today's networks, handling all traffic coming from access networks (e.g., DSL traffic), applying operator policies and providing the first IP point in the network. It is perhaps unsurprising then, that these are expensive, proprietary, difficult-to-upgrade boxes. They also represent a large, single point of failure, making operators even more reticent to deploy new functionality for fear it might seriously disrupt day-to-day operations. In order to remove some of these barriers to innovation, we advocate for turning BRASes from the monolithic hardware boxes they are today into flexible, virtualized, software-based devices running on inexpensive commodity hardware. As a proofof-concept, we present the implementation and performance of a software BRAS based on ClickOS, a tiny Xen virtual machine designed specifically for network processing. Our software BRAS prototype can establish subscriber sessions at rates above 1, 000 per second, requires only 1MB of memory per 1, 000 established sessions, can boot in milliseconds, and can handle traffic at 10Gb/s for almost all packet sizes.