Enabling Transparent Caching in LTE Mobile Backhaul Networks with SDN

Today's mobile network architecture lacks the flexibility needed to efficiently handle the fast increasing amount of data traffic. SDN could provide the required flexibility in future mobile architectures, but its introduction into the existing architectures is challenging. In this paper we propose a solution to improve the mobile backhaul's flexibility based on SDN, compatible with the current architecture, exploring the use case of transparent in-network caching. We explore the design space in terms function placement, and propose a scalable solution for in-network caching based on stateless DPI and stateful connection tracking. We implemented a prototype of the proposed solution to evaluate its impact on MPEG DASH streaming performance. Our experimental results show that the delay introduced by the developed module is less than 5ms for 99% of the packets, which is negligible in today's LTE networks, and the slight negative impact on streaming rate selection is easily outweighed by the increased flexibility.