Modelling & Improving Flow Establishment in RSVP

RSVP has developed as a key component for the evolving Internet, and in particular for the Integrated Services Architecture. Therefore, RSVP performance is crucially important; yet this has been little studied up till now. In this paper, we target one of the most important aspects of RSVP: its ability to establish flows. We first identify the factors influencing the performance of the protocol by modelling the establishment mechanism. Then, we propose a Fast Establishment Mechanism (FEM) aimed at speeding up the set-up procedure in RSVP. We analyse FEM by means of simulation, and show that it offers improvements to the performance of RSVP over a range of likely circumstances

Peer-to-Peer vs. the Internet: A Discussion on the Proper and Practical Location of Functionality

Peer-to-peer information sharing has become one of the dominant Internet applications, measured not only in the number of users, but also in the network bandwidth consumed. Thus, it is reasonable to examine the location of support functionality such as self-organisation, resource discovery, multipoint-to-multipoint group communication, forwarding, and routing, to provide the needed service to applications while optimising resource usage in the network. This position paper is intended to stimulate discussion in two related areas: First, where {em should} functionality to support peer-to-peer applications be located: in the network, or as an application overlay among end systems. Second, where {em can} functionality be located, given the practical constraints of the modern Internet including closed systems and middleboxes, as well as administrative, legal, and social issues. We will discuss the performance implications of these decisions, including whether low latency bounds for delay sensitive peer-to-peer applications (such as distributed network computing) can ever be achieved in this environment

Mobile Networking

We point out the different performance problems that need to be addressed when considering mobility in IP networks. We also define the reference architecture and present a framework to classify the different solutions for mobility management in IP networks. The performance of the major candidate micro-mobility solutions is evaluated for both real-time (UDP) and data (TCP) traffic through simulation and by means of an analytical model. Using these models we compare the performance of different mobility management schemes for different data and real-time services and the network resources that are needed for it. We point out the problems of TCP in wireless environments and review some proposed enhancements to TCP that aim at improving TCP performance. We make a detailed study of how some of micro-mobility protocols namely Cellular IP, Hawaii and Hierarchical Mobile IP affect the behavior of TCP and their interaction with the MAC layer. We investigate the impact of handoffs on TCP by means of simulation traces that show the evolution of segments and acknowledgments during handoffs.Publicad

Sliver: A BPEL Workflow Process Execution Engine for Mobile Devices

The Business Process Execution Language (BPEL) has become the dominant means for expressing traditional business processes as workflows. The widespread deployment of mobile devices like PDAs and mobile phones has created a vast computational and communication resource for these workflows to exploit. However, BPEL so far has been deployed only on relatively heavyweight server platforms such as Apache Tomcat, leaving the potential created by these lower-end devices untapped. This paper presents Sliver, a BPEL workflow process execution engine that supports a wide variety of devices ranging from mobile phones to desktop PCs. We discuss the design decisions that allow Sliver to operate within the limited resources of a mobile phone or PDA. We also evaluate the performance of a prototype implementation of Sliver

Virtuoso: High Resource Utilization and {\mu}s-scale Performance Isolation in a Shared Virtual Machine TCP Network Stack

Virtualization improves resource efficiency and ensures security and performance isolation for cloud applications. To that end, operators today use a layered architecture that runs a separate network stack instance in each VM and container connected to a separate virtual switch. Decoupling through layering reduces complexity, but induces performance and resource overheads that are at odds with increasing demands for network bandwidth, communication requirements for large distributed applications, and low latency. We present Virtuoso, a new software networking stack for VMs and containers. Virtuoso performs a fundamental re-organization of the networking stack to maximize CPU utilization, enforce isolation, and minimize networking stack overheads. We maximize utilization by running one elastically shared network stack instance on dedicated cores; we enforce isolation by performing central and fine-grained per-packet resource accounting and scheduling; we reduce overheads by building a single-layer data path with a one-shot fast-path incorporating all processing from the TCP transport layer through network virtualization and virtual switching. Virtuoso improves resource utilization by up to 50%, latencies by up to 42% compared to other virtualized network stacks without sacrificing isolation, and keeps processing overhead within 11.5% of unvirtualized network stacks.Comment: Under submission for conference peer revie

Extending BPEL for Interoperable Pervasive Computing

The widespread deployment of mobile devices like PDAs and mobile phones has created a vast computation and communication platform for pervasive computing applications. However, these devices feature an array of incompatible hardware and software architectures, discouraging ad-hoc interactions among devices. The Business Process Execution Language (BPEL) allows users in wired computing settings to model applications of significant complexity, leveraging Web standards to guarantee interoperability. However, BPEL\u27s inflexible communication model effectively prohibits its deployment on the kinds of dynamic wireless networks used by most pervasive computing devices. This paper presents extensions to BPEL that address these restrictions, transforming BPEL into a versatile platform for interoperable pervasive computing applications. We discuss our implementation of these extensions in Sliver, a lightweight BPEL execution engine that we have developed for mobile devices. We also evaluate a pervasive computing application prototype implemented in BPEL, running on Sliver