No abstract

No abstract

Software defined networking (SDN) represents a new approach in which the decision-making process of the network is moved from distributed network devices to a logically centralized controller, implemented as software running on commodity servers. This enables more automation and optimization of the network and, when combined with software defined compute and software defined storage, forms one of the three pillars of IBM's software defined environment (SDE). This paper provides an overview of SDN, focusing on several technologies gaining attention and the benefits they provide for cloud-computing providers and end-users. These technologies include (i) logically centralized SDN controllers to manage virtual and physical networks, (ii) new abstractions for virtual networks and network virtualization, and (iii) new routing algorithms that eliminate limitations of traditional Ethernet routing and allow newer network topologies. Additionally, we present IBM's vision for SDN, describing how these technologies work together to virtualize the underlying physical network infrastructure and automate resource provisioning. The vision includes automated provisioning of multi-tier applications, application performance monitoring, and the enabling of dynamic adaptation of network resources to application workloads. Finally, we explore the implications of SDN on network topologies, quality of service, and middleboxes (e.g., network appliances).

No abstract

Understanding and managing the response time of web services is of key importance as dependence on the World Wide Web continues to grow. We present Remote Latency-based Management (RLM), a novel server-side approach for managing pageview response times as perceived by remote clients, in real-time. RLM passively monitors server-side network traffic, accurately tracks the progress of page downloads and their response times in real-time, and dynamically adapts connection setup behavior and web page content as needed to meet response time goals. To manage client perceived pageview response times, RLM builds a novel event node model to guide the use of several techniques for manipulating the packet traffic in and out of a web server complex, including fast SYN and SYN/ACK retransmission, and embedded object removal and rewrite. RLM operates as a stand-alone appliance that simply sits in front of a web server complex, without any changes to existing web clients, servers, or applications. We have implemented RLM on an inexpensive, commodity, Linux-based PC and present experimental results that demonstrate its effectiveness in managing client perceived pageview response times on transactional e-commerce web workloads.