SoftCell: Taking Control of Cellular Core Networks

TL;DR

SoftCell introduces a scalable, flexible architecture for cellular core networks that supports fine-grained policies, reduces data-plane state, and maintains connection consistency amidst mobility, using commodity switches and middleboxes.

Contribution

The paper presents SoftCell, a novel architecture that enhances cellular network flexibility and scalability by hierarchical addressing and policy tagging, minimizing core switch state.

Findings

Improves network flexibility and policy support.

Reduces core switch state and costs.

Maintains connection consistency during mobility.

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.