Hans-Joerg Kolbe

Flexible traffic management in broadband access networks using Software Defined Networking

Over the years, the demand for high bandwidth services, such as live and on-demand video streaming, steadily increased. The adequate provisioning of such services is challenging and requires complex network management mechanisms to be implemented by Internet service providers (ISPs). In current broadband network architectures, the traffic of subscribers is tunneled through a single aggregation point, independent of the different service types it belongs to. While having a single aggregation point eases the management of subscribers for the ISP, it implies huge bandwidth requirements for the aggregation point and potentially high end-to-end latency for subscribers. An alternative would be a distributed subscriber management, adding more complexity to the management itself. In this paper, a new traffic management architecture is proposed that uses the concept of Software Defined Networking (SDN) to extend the existing Ethernet-based broadband network architecture, enabling a more efficient traffic management for an ISP. By using SDN-enabled home gateways, the ISP can configure traffic flows more dynamically, optimizing throughput in the network, especially for bandwidth-intensive services. Furthermore, a proof-of-concept implementation of the approach is presented to show the general feasibility and study configuration tradeoffs. Analytic considerations and testbed measurements show that the approach scales well with an increasing number of subscriber sessions.

Rethinking Access Networks with High Performance Virtual Software BRASes

Broadband Remote Access Servers (BRASes) play a crucial role in todays 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.

Enhancing the BRAS through virtualization

Broadband Remote Access Servers (BRASes) are crucial middleboxes in DSL access networks, providing the first IP point in the network for subscribers and enforcing operator policies. The number of functions provided by BRASes, combined with the key role they play in the network, means that these devices are expensive, difficult to change, and constitute a single point of failure. In order to overcome these limitations, we propose to virtualize the BRAS and to enhance it with a control interface that can be exploited by management systems in order to introduce live session migration and higher reliability. Our proof-of-concept implementation shows that our virtual software BRAS is able to handle thousands of sessions while forwarding and shaping traffic at rates of millions of packets per second on commodity hardware, and that the live session migration feature enables the implementation of high-reliability scenarios.