Dual-Mode UltraFlow Access Networks: a Hybrid Solution for the Access Bottleneck Leonid G. Kazovsky, Thomas Shunrong Shen, Ahmad. R. Dhaini, Shuang Yin, Marc De Leenheer, Benjamin A. Detwiler Photonics and Networking Research Laboratory (PNRL), Stanford University, USA ABSTRACT Optical Flow Switching (OFS) is a promising solution for large Internet data transfers. In this paper, we introduce UltraFlow Access, a novel optical access network architecture that offers dual-mode service to its end-users: IP and OFS. With UltraFlow Access, we design and implement a new dual-mode control plane and a new dual-mode network stack to ensure efficient connection setup and reliable and optimal data transmission. We study the impact of the UltraFlow system’s design on the network throughput. Our experimental results show that with an optimized system design, near optimal (around 10 Gb/s) OFS data throughput can be attained when the line rate is 10Gb/s. Keywords: Dual-mode transmission, optical access network, optical flow switching, passive optical network 1. INTRODUCTION In recent years, the Internet has been challenged by stringent requirements such as very high-speed data rates (10 Gb/s and higher), low packet latency, energy efficiency, and fast switching. For over half a century, store-and-forward Electrical Packet Switching (EPS) with Layer 3 routing has been regarded as an efficient solution for relatively low-to- medium high-speed data transmission (≤ 1 Gb/s). However, the proliferation of bandwidth-intensive applications such as high-definition (HD) video streaming, large file transfer and high-speed data transmission (many Gbps) have been challenging the IP routing overhead and EPS throughput. Consequently, Optical Flow Switching (OFS) has been proposed as an efficient solution in which OFS connections (also referred to as Flow connections), with dedicated lightpaths, bypass IP routers to enable efficient end-to-end optical communication for high volume transmission [1]. As illustrated in Fig. 1, with OFS, access networks are connected through the metropolitan and wide area networks (MAN/WAN) using optical-cross-connect switches (OXCs); unlike EPS, no buffering occurs between the source and destination. A single Flow connection is envisioned to remain in the network for a time period larger than 100 ms [1-2]. The scheduling of Flow lightpaths is conducted using centralized network edge schedulers coordinated through an electronic control plane (typically via legacy IP) [1-2]. Figure 1. Illustration of OFS operation with Flow and control channels connecting via the Access, MAN and WAN. WAN MAN Access Access MAN OFLT OFLT OFNU Data Server Edge Scheduler Core Scheduler Edge Scheduler Flow control channel Flow channel