Ashok Sunder Rajan

Understanding the bottlenecks in virtualizing cellular core network functions

Network function virtualization (NFV) promises significant cost savings, flexibility and ease of deployment. However, potential challenges in implementing virtualized network elements that can support real-world performance requirements are still an open question. For example, traditional telecom networks have a lot of complex interdependencies that can affect performance. In this paper, we study the potential bottlenecks in virtualizing cellular core network functions. Using a combination of analysis and experimentation, we quantify the impact of software-based EPC elements on various metrics including physical processing, memory, IO, and bandwidth resource requirements. We use production grade, software-based cellular network elements running on general purpose Linux servers, driven by a variety of realistic workloads derived from a realworld cellular network, to examine the combined effects of control and data planes on an LTE enhanced packet core (EPC). In particular, we discover that the SGW handles about 33% of the control plane transactions and is a potential source for performance bottlenecks as a result of the interdependencies between control and data plane processing. Our results indicate that simply replacing existing EPC elements with virtualized equivalents can have severe performance bottlenecks and that virtualized EPC elements need to be carefully designed.

High-performance evolved packet core signaling and bearer processing on general-purpose processors

Telecommunications service providers are exploring the use of standard high-volume servers to reduce total cost of ownership while at the same time increasing flexibility, service velocity, and scalability of network functions. This article characterizes performance of general-purpose processors - specifically x86 architecture processors - for signaling and bearer processing representative of a wireless carriers call model for a Long Term Evolution Evolved Packet Core. A radio access network emulator was used to stimulate an Evolved Packet Core software stack running on an x86 server. The goal was to prove that standard high-volume servers can execute EPC functions per representative market call models, and that workloads can scale across bearer and control plane at line rate without acceleration technologies. A call model was developed to quantify the performance on Intel® Xeon® Processor based servers using an LTE traffic simulator and a commercial EPC software stack. The traffic models represent bidirectional real-world network traffic during different times of the day. The results were that the test EPC processed control and user plane traffic with 50,000 subscribers with a total payload of 10 Gb/s downlink + 4.8 Gb/s uplink traffic using five cores for the data plane and eight cores for the rest of the system; and the user plane throughput scaled in a single blade environment to 20 Gb/s per socket or 40 Gb/s for a dual socket blade.

An IoT control plane model and its impact analysis on a virtualized MME for connected cars

IoT drives the future of Connected Cars including smart cars and it will transform the way we interact with our vehicles. With the emergence of millions of connected cars in the horizon, the wireless infrastructure needed to support this capability has to scale efficiently. To better understand the impact on the resource utilization of the wireless core infrastructure, we provide a detailed statistical model of the control plane/signaling interactions in connected cars. Specifically, our model is based on a 40K sample data set spanning more than 2100 IoT vehicles collected over 20 hours from a national telecommunications provider. The control plane model quantifies the additional load that the infrastructure (e.g., MME) needs to handle compared to an average busy hour LTE traffic model. We identify the heavy hitters of the control plane events and run real experiments based on our models in a testbed to characterize the resource utilization for supporting total event loadings using a real world high performance virtualized MME. No personally identifiable information (PII) was gathered or used in conducting this study. To the extent any data was analyzed, it was anonymous and/or aggregated data.

Considerations for re-designing the cellular infrastructure exploiting software-based networks

As demand for wireless mobile connectivity continues to explode, cellular network infrastructure capacity requirements continue to grow. While 5G tries to address capacity requirements at the radio layer, the load on the cellular core network infrastructure (called Enhanced Packet Core (EPC)) stresses the network infrastructure. Our work examines the architecture, protocols of current cellular infrastructures and the workload on the EPC. We study the challenges in dimensioning capacity and review the design alternatives to support the significant scale up desired, even for the near future. We breakdown the workload on the network infrastructure into its components-signaling event transactions; database or lookup transactions and packet processing. We quantitatively show the control plane and data plane load on the various components of the EPC and estimate how future 5G cellular network workloads will scale. This analysis helps us to understand the scalability challenges for future 5G EPC network components. Other efforts to scale the 5G cellular network take a system view where the control plane is separated from the data path and is terminated on a centralized SDN controller. The SDN controller configures the data path on a widely distributed switching infrastructure. Our analysis of the workload informs us on the feasibility of various design alternatives and motivates our efforts to develop our clean-slate approach, called CleanG.