System Support for Bandwidth Management and Content Adaptation in Internet Applications

This paper describes the implementation and evaluation of an operating system module, the Congestion Manager (CM), which provides integrated network flow management and exports a convenient programming interface that allows applications to be notified of, and adapt to, changing network conditions. We describe the API by which applications interface with the CM, and the architectural considerations that factored into the design. To evaluate the architecture and API, we describe our implementations of TCP; a streaming layered audio/video application; and an interactive audio application using the CM, and show that they achieve adaptive behavior without incurring much end-system overhead. All flows including TCP benefit from the sharing of congestion information, and applications are able to incorporate new functionality such as congestion control and adaptive behavior.Comment: 14 pages, appeared in OSDI 200

The Impact of SCTP on Server Scalability and Performance

The Stream Control Transmission Protocol (SCTP) is a newer transport protocol, having additional features to TCP. Although SCTP is an alternative transport protocol for the Session Initiation Protocol (SIP), we do not know how SCTP features influence SIP server scalability and performance. To estimate this, we measured the scalability and performance of two servers, an echo server and a simplified SIP server on Linux, comparing to TCP. Our measurements found that using SCTP does not significantly affect on data latency: approximately 0.3 ms longer for the handshake than that for TCP. However, server scalability in terms of the number of sustainable associations drops to 17-21%, or to 43% of TCP if we adjust the acceptable gap size of unordered data delivery

One Server Per City: Using TCP for Very Large SIP Servers

The transport protocol for SIP can be chosen based on the requirements of services and network conditions. How does the choice of TCP affect the scalability and performance compared to UDP? We experimentally analyze the impact of using TCP as a transport protocol for a SIP server. We first investigate scalability of a TCP echo server, then compare performance of a SIP server for three TCP connection lifetimes: transaction, dialog, and persistent. Our results show that a Linux machine can establish 450,000+ TCP connections and maintaining connections does not affect the transaction response time. Additionally, the transaction response times using the three TCP connection lifetimes and UDP show no significant difference at 2,500 registration requests/second and at 500 call requests/second. However, sustainable request rate is lower for TCP than for UDP, since using TCP requires more message processing. More message processing causes longer delays at the thread queue for the server implementing a thread-pool model. Finally, we suggest how to reduce the impact of TCP for a scalable SIP server especially under overload control. This is applicable to other servers with very large connection counts

HLA high performance and real-time simulation studies with CERTI

Our work takes place in the context of the HLA standard and its application in real-time systems context. Indeed, current HLA standard is inadequate for taking into consideration the different constraints involved in real-time computer systems. Many works have been invested in order to provide real-time capabilities to Run Time Infrastructures (RTI). This paper describes our approach focusing on achieving hard real-time properties for HLA federations through a complete state of the art on the related domain. Our paper also proposes a global bottom up approach from basic hardware and software basic requirements to experimental tests for validation of distributed real-time simulation with CERTI

HP-CERTI: Towards a high performance, high availability open source RTI for composable simulations (04F-SIW-014)

Composing simulations of complex systems from already existing simulation components remains a challenging issue. Motivations for composable simulation include generation of a given federation driven by operational requirements provided "on the fly". The High Level Architecture, initially developed for designing fully distributed simulations, can be considered as an interoperability standard for composing simulations from existing components. Requirements for constructing such complex simulations are quite different from those discussed for distributed simulations. Although interoperability and reusability remain essential, both high performance and availability have also to be considered to fulfill the requirements of the end user. ONERA is currently designing a High Performance / High Availability HLA Run-time Infrastructure from its open source implementation of HLA 1.3 specifications. HP-CERTI is a software package including two main components: the first one, SHM-CERTI, provides an optimized version of CERTI based on a shared memory communication scheme; the second one, Kerrighed-CERTI, allows the deployment of CERTI through the control of the Kerrighed Single System Image operating system for clusters, currently designed by IRISA. This paper describes the design of both high performance and availability Runtime Infrastructures, focusing on the architecture of SHM-CERTI. This work is carried out in the context of the COCA (High Performance Distributed Simulation and Models Reuse) Project, sponsored by the DGA/STTC (Délégation Générale pour l'Armement/Service des Stratégies Techniques et des Technologies Communes) of the French Ministry of Defense

A Framework for Comparative Evaluation of High-Performance Virtualized Networking Mechanisms

This paper presents an extension to a software framework designed to evaluate the efficiency of different software and hardware-accelerated virtual switches, each commonly adopted on Linux to provide virtual network connectivity to containers in high-performance scenarios, like in Network Function Virtualization (NFV). We present results from the use of our tools, showing the performance of multiple high-performance networking frameworks on a specific platform, comparing the collected data for various key metrics, namely throughput, latency and scalability, with respect to the required computational power

Network Access in a Diversified Internet

There is a growing interest in virtualized network infrastructures as a means to enable experimental evaluation of new network architectures on a realistic scale. The National Science Foundation\u27s GENI initiative seeks to develop a national experimental facility that would include virtualized network platforms that can support many concurrent experimental networks. Some researchers seek to make virtualization a central architectural component of a future Internet, so that new network architectures can be introduced at any time, without the barriers to entry that currently make this difficult. This paper focuses on how to extend the concept of virtualized networking through LAN-based access networks to the end systems. Our objective is to allow virtual networks that support new network services to make those services directly available to applications, rather than force applications to access them indirectly through existing network protocols. We demonstrate that this approach can improve performance by an order of magnitude over other approaches and can enable virtual networks that provide end-to-end quality of service

Parallel network protocol stacks using replication

Computing applications demand good performance from networking systems. This includes high-bandwidth communication using protocols with sophisticated features such as ordering, reliability, and congestion control. Much of this protocol processing occurs in software, both on desktop systems and servers. Multi-processing is a requirement on today\u27s computer architectures because their design does not allow for increased processor frequencies. At the same time, network bandwidths continue to increase. In order to meet application demand for throughput, protocol processing must be parallel to leverage the full capabilities of multi-processor or multi-core systems. Existing parallelization strategies have performance difficulties that limit their scalability and their application to single, high-speed data streams. This dissertation introduces a new approach to parallelizing network protocol processing without the need for locks or for global state. Rather than maintain global states, each processor maintains its own copy of protocol state. Therefore, updates are local and don\u27t require fine-grained locks or explicit synchronization. State management work is replicated, but logically independent work is parallelized. Along with the approach, this dissertation describes Dominoes, a new framework for implementing replicated processing systems. Dominoes organizes the state information into Domains and the communication into Channels. These two abstractions provide a powerful, but flexible model for testing the replication approach. This dissertation uses Dominoes to build a replicated network protocol system. The performance of common protocols, such as TCP/IP, is increased by multiprocessing single connections. On commodity hardware, throughput increases between 15-300% depending on the type of communication. Most gains are possible when communicating with unmodified peer implementations, such as Linux. In addition to quantitative results, protocol behavior is studied as it relates to the replication approach