Kenichi Nagami

A measurement of mobile traffic offloading

A promising way to use limited 3G mobile resources efficiently is 3G mobile traffic offloading through WiFi by the user side. However, we currently do not know enough about how effective the mobile traffic offloading is in the wild. In this paper, we report the results of a two-day-long user-based measurement of mobile traffic offloading by over 400 android smartphone users in Japan. We first explain that the variation of aggregated traffic volume via WiFi is much greater than that via 3G in our dataset. Next, we show that the traffic volume offloading through WiFi is common over whole weekend and weekday night, though weekday rush hours have less chance of traffic offloading. Our results emphasize that a small fraction of users contribute to a large fraction of offload traffic volume. In fact, our per-user level analysis reveals that the top 30% of users downloaded over 90% of their total traffic volume via WiFi. However, bottom 20% of users stuck to 3G only and over 50% of users turned off the WiFi interface in business hours. Also, 17.4% of the total traffic volume was generated by users whose WiFi traffic volume was less than 1MB. We observed that some hybrid users downloaded most of their traffic volume via WiFi in shorter durations. In this sense, there is more room to improve the current traffic offloading by promoting users to use WiFi more effectively. Furthermore, we demonstrate that WiFi offloading is mainly performed by access points (APs) in homes while the use of public WiFi APs is still uncommon in our dataset.

Tracking the Evolution and Diversity in Network Usage of Smartphones

We analyze the evolution of smartphone usage from a dataset obtained from three, 15-day-long, user-side, measurements with over 1500 recruited smartphone users in the Greater Tokyo area from 2013 to 2015. This dataset shows users across a diverse range of networks; cellular access (3G to LTE), WiFi access (2.4 to 5GHz), deployment of more public WiFi access points (APs), as they use diverse applications such as video, file synchronization, and major software updates. Our analysis shows that smartphone users select appropriate network interfaces taking into account the deployment of emerging technologies, their bandwidth demand, and their economic constraints. Thus, users show diversity in both how much traffic they send, as well as on what networks they send it. We show that users are gradually but steadily adopting WiFi at home, in offices, and public spaces over these three years. The majority of light users have been shifting their traffic to WiFi. Heavy hitters acquire more bandwidth via WiFi, especially at home. The percentage of users explicitly turning off their WiFi interface during the day decreases from 50% to 40%. Our results highlight that the offloading environment has been improved during the three years, with more than 40% of WiFi users connecting to multiple WiFi APs in one day. WiFi offload at offices is still limited in our dataset due to a few accessible APs, but WiFi APs in public spaces have been an alternative to cellular access for users who request not only simple connectivity but also bandwidth-consuming applications such as video streaming and software updates.

Design and evaluation of a P2MP MPLS-based hierarchical service management system

This paper proposes a point-to-multipoint (P2MP) Multi-Protocol Label Switching (MPLS) based hierarchical service management system. Traditionally, general management systems deployed in some service providers control MPLS label switched paths (LSPs) (e.g. RSVP-TE, LDP) and services (e.g. L2VPN, L3VPN and IP) separately. In order for the dedicated management systems for MPLS LSPs and services to cooperate with each other automatically, a hierarchical service management system has been proposed with the main focus on point-to-point (P2P) TE LSPs in MPLS path management. In the case where P2MP TE LSPs and services are deployed in MPLS networks, the dedicated management systems for P2MP TE LSPs and services must work together automatically. Therefore, this paper proposes a new automatic correlation between P2MP TE LSPs and each service. In particular, this paper proposes a new algorithm for a correlation between P2MP TE LSPs and multicast VPN services. The capacity and performance searching on both a sub-LSP and correlation tables are evaluated, and the results show this system is very scalable within real MPLS production networks. This system, with automatic correlation, appears to be deployable in real MPLS production networks.

BGP Extension for MPLS P2MP-LSP

Contents delivery services are deployed over the Internet and its technology. Contents delivery services demand high quality. Consequently, a large network capacity is required. In order to efficiently deliver such contents and to meet high quality demands, network operators are required to explicitly indicate the branch node and/or the link so that packets are efficiently sent. Fast restoration at the time of trouble has become an important issue. MPLS technology has been utilized to realize Traffic Engineering and Fast Reroute to cope with this issue. However, only a point-to-point path is allowed in the current MPLS technology. To allow an efficient high-quality contents delivery, a point-to-multipoint path called as P2MP-LSP is under discussion. However, proposed methods lack of getting information about P2MP-LSP node due to the current MPLS signaling method to establish P2MP-LSP. This paper introduces a discovery technique of the P2MP-LSP node and an establishment technique of the P2MP-LSP using BGP. In addition, a basic function of this proposal is experimented, and its practicality is evaluated.