SoftCell: Taking control of Cellular Core Networks

Abstract:

Existing cellular networks suffer from inflexible and expensive
equipment, and complex control-plane protocols. To
address these challenges, we present SoftCell, a scalable architecture
for supporting fine-grained policies for mobile devices
in cellular core networks. The SoftCell controller realizes
high-level service polices by directing traffic over paths
that traverse a sequence of middleboxes, optimized to the
network conditions and user locations. To ensure scalability,
the core switches forward traffic on hierarchical addresses
(grouped by base station) and policy tags (identifying paths
through middleboxes). This minimizes data-plane state in
the core switches, and pushes all fine-grained state to software
switches at the base stations. These access switches apply
fine-grained rules, specified by the controller, to map all
traffic to the appropriate addresses and tags. SoftCell guarantees
that packets in the same connection traverse the same
sequence of middleboxes in both directions, even in the presence
of mobility. Our characterization of real LTE workloads,
micro-benchmarks on our prototype controller, and
large-scale simulations demonstrate that SoftCell improves
the flexibility of cellular core networks, while enabling the
use of inexpensive commodity switches and middleboxes.