Ramin Khalili

MSPlayer: Multi-Source and Multi-Path Video Streaming

Online video streaming through mobile devices has become extremely popular nowadays. YouTube, for example, reported that the percentage of its traffic streaming to mobile devices has soared from 6% to more than 40% over the past two years. Moreover, people are constantly seeking to stream high-quality videos for better experience while often suffering from limited bandwidth. With the rapid deployment of content delivery networks, popular videos are now replicated at different sites, and users can stream over-the-top videos from close-by sources with low latency. Aggregating bandwidth for high definition video streaming has become possible as mobile devices, nowadays, are equipped with multiple wireless interfaces (e.g., WiFi and 3G/4G). We propose a client-based video streaming solution, MSPlayer, that takes advantage of multiple video sources and leverages multiple network paths through different interfaces. MSPlayer reduces start-up latency and provides robust data transport with high video quality in mobile scenarios. We experimentally demonstrate our solution on a test bed and through the YouTube video service.

Understanding processing latency of SDN based mobility management in mobile core networks

Current solutions to evolve mobility management in Mobile Core Networks (MCN) based on SDN have showed the gain in flexibility and how to reduce control signaling. However, these works neglect the problems of describing the design choices of SDN Mobility Management Applications (MMA) and identifying where and what are the critical processing latency contributors for such design. Our paper addresses these problems. We study the internal mechanisms and interactions of MMA and controller, to determine the contributors to the overall processing latency. We implemented two MMA solutions (based on reactive and proactive designs) as modules of Floodlight, and we run experiments using Mininet and OpenFlow. The proactive MMA design can guarantee that the overall processing latency in the 95th percentile can be kept near the median value, given available CPU capacity at the SDN controller. One key lesson learned with our study is that only optimizing control signaling of MMA is not enough to provide better overall processing latency.

Dispatching PACKET_INs to the right SDN control application via context interpretation in Mobile Core Networks

Telco operators started to apply the SDN technologies also in the design of Mobile Core Networks (MCNs). In this change towards SDNized Mobile Core Network, it is crucial to understand how conventional interfaces among different mobile network entities should evolve. The issues derived from this change have not been tackled by current research approaches. This paper presents the first initiative to close this research gap. We tackle the key problem of how to identify which mobile SDN applications (APPs) should be invoked once a PACKET_IN (the OpenFlow message that transport information from the data plane to the control plane) is received at the control level. We propose data structures, a model, and detailed examples of three important PACKET_IN context interpretation for MCNs. Initial experiments, based on Floodlight controller and Mininet emulation environment were carried out. The results indicate that it is feasible to use our proposed approach to dispatch PACKET_INs to the right SDN APP. The delay introduced due to invocation of such mechanism to interpret the context of the PACKET_IN and activate the appropriate mobile SDN APPs is only in the order of microseconds. Our proposal can be used to simplify current Mobile Core Network interface design by exploiting the SDN mechanisms. We believe, this work helps to pave the way towards fully SDNized Mobile Core Networks.

Identifying latency factors in SDN-based Mobile Core Networks

Software Defined Networking (SDN) is considered one of the major driving factors to bring radical changes on Mobile Core Networks (MCN) design. There are many proposals on how to advocate SDN methodology, however, most of them stop at “vision” level without providing details about key performance contributors. In this paper, we tackle this gap and present a study of latency in SDN based MCN. We identify the major factors and elements in an SDN MCN that contribute to the overall latency. Two types of latency are considered: the processing delay inside the SDN control plane and the transmission delay of SDN control messages between controller and the managed switches. We use a realistic system setup with implementations of SDN controller and SDN application, as well as in-band transfer of control messages among switches and controller. We compare the latency obtained from SDN based MCN with the Evolved Packet Core (EPC). The observed overall latency in our experiments for SDN based MCN is within the EPC requirements. The direct comparison of the SDN versus EPC based MCN in the proposed scenarios show the first can reduce the overall latency. We also identified that the calls to controller APIs can be the major key contributors to the overall latency in SDN MCN, but the act of transmitting more control messages from the controller to the switches to setup longer flowpaths is not a key contributor for the overall latency.

Performance comparison of node-redundant multicast distribution trees in SDN networks

Some of the industrial processes with hard real-time constraints, such as those commonly found in the context of smart grids, require very reliable packet delivery and multicast. Solutions such as PRP assume deployments over redundant and dedicated networks. SDN gives us an unprecedented opportunity to obtain the same result by using a shared telecom infrastructure instead of privately owned networks. Nevertheless, there is a challenging question of how to provide node-redundant multicast-distribution-trees. We review existing graph-theoretical algorithms that were proposed for similar problems and propose three algorithms that are suitable for our smart-grid setting. Then, we evaluate their performance in the context of SDN networks. We use as metrics the number of forwarding rules that need to be installed on SDN switches, the number of hops between source-destination pairs given the installed forwarding rules, and the number of sources that can be placed in the network given the capacity constraints.

SDN on ACIDs

Software-defined networks (SDN) do not guarantee coherent network operations, when uncoordinated SDN applications concurrently update the network forwarding state. As this problem has not so far received considerable attention, in this paper, we introduce transactional network-wide update support in SDN. We notably design and implement a new SDN service complementing state of the art proposals to achieve atomicity, isolation and durability of network updates in any typical SDN setup. The experiments with our implementation of the ACID service in FloodLight and OpenVSwitch demonstrate the practical feasibility of our proposal and good scalability to different network loads and sizes.