FCAST: Object Delivery for the Asynchronous Layered Coding (ALC) and NACK-Oriented Reliable Multicast (NORM) Protocols

Internet Engineering Task Force (IETF) Request for Comments 6968 (RFC 6968)This document introduces the FCAST reliable object (e.g., file) delivery application. It is designed to operate either on top of the underlying Asynchronous Layered Coding (ALC) / Layered Coding Transport (LCT) reliable multicast transport protocol or the NACK-Oriented Reliable Multicast (NORM) transport protocol

To NACK or not to NACK? Negative Acknowledgments in Information-Centric Networking

Information-Centric Networking (ICN) is an internetworking paradigm that offers an alternative to the current IP\nobreakdash-based Internet architecture. ICN's most distinguishing feature is its emphasis on information (content) instead of communication endpoints. One important open issue in ICN is whether negative acknowledgments (NACKs) at the network layer are useful for notifying downstream nodes about forwarding failures, or requests for incorrect or non-existent information. In benign settings, NACKs are beneficial for ICN architectures, such as CCNx and NDN, since they flush state in routers and notify consumers. In terms of security, NACKs seem useful as they can help mitigating so-called Interest Flooding attacks. However, as we show in this paper, network-layer NACKs also have some unpleasant security implications. We consider several types of NACKs and discuss their security design requirements and implications. We also demonstrate that providing secure NACKs triggers the threat of producer-bound flooding attacks. Although we discuss some potential countermeasures to these attacks, the main conclusion of this paper is that network-layer NACKs are best avoided, at least for security reasons.Comment: 10 pages, 7 figure

Distributed OpenGL Rendering in Network Bandwidth Constrained Environments

Display walls made from multiple monitors are often used when very high resolution images are required. To utilise a display wall, rendering information must be sent to each computer that the monitors are connect to. The network is often the performance bottleneck for demanding applications, like high performance 3D animations. This paper introduces ClusterGL; a distribution library for OpenGL applications. ClusterGL reduces network traffic by using compression, frame differencing and multi-cast. Existing applications can use ClusterGL without recompilation. Benchmarks show that, for most applications, ClusterGL outperforms other systems that support unmodified OpenGL applications including Chromium and BroadcastGL. The difference is larger for more complex scene geometries and when there are more display machines. For example, when rendering OpenArena, ClusterGL outperforms Chromium by over 300% on the Symphony display wall at The University of Waikato, New Zealand. This display has 20 monitors supported by five computers connected by gigabit Ethernet, with a full resolution of over 35 megapixels. ClusterGL is freely available via Google Code

Speeding Multicast by Acknowledgment Reduction Technique (SMART)

We present a novel feedback protocol for wireless broadcast networks that utilize linear network coding. We consider transmission of packets from one source to many receivers over a single-hop broadcast erasure channel. Our method utilizes a predictive model to request feedback only when the probability that all receivers have completed decoding is significant. In addition, our proposed NACK-based feedback mechanism enables all receivers to request, within a single time slot, the number of retransmissions needed for successful decoding. We present simulation results as well as analytical results that show the favorable scalability of our technique as the number of receivers, file size, and packet erasure probability increase. We also show the robustness of this scheme to uncertainty in the predictive model, including uncertainty in the number of receiving nodes and the packet erasure probability, as well as to losses of the feedback itself. Our scheme, SMART, is shown to perform nearly as well as an omniscient transmitter that requires no feedback. Furthermore, SMART, is shown to outperform current state of the art methods at any given erasure probability, file size, and numbers of receivers

Improving wireless multicast communications with NC: performance assessment over a COTS platform

Multicast services are believed to play a relevant role in next wireless networking scenarios. In this paper we exploit Tunable Sparse Network Coding techniques to increase reliability of multicast communications. We show that the proposed network coding scheme yields a better performance than state-of-the-art solutions, which are traditionally based on retransmissions. We first use a model to analytically compare the two approaches. Then, we validate and broaden this analysis by means of an experimental campaign over a testbed deployed with Commercial Of-The-Shelf devices. This platform, comprising low cost devices (Raspberry-PI), allows us to assess the feasibility of the proposed solution, which offers a relevant gain in terms of performance.This work has been supported by the Spanish Government (Ministerio de Economía y Competitividad, Fondo Europeo de Desarrollo Regional, FEDER) by means of the project ADVICE (TEC2015-71329-C2-1-R)

A Comparison of Different TCP/IP and DTN Protocols Over the D-Star Digital Data Mode

This paper examines the performance of the Digital Smart Technologies for Amateur Radio - Digital Data mode with various IP and non-IP based protocols. A throughput comparison was performed between IPv4, IPv6, the DTN Convergence Layer and the NORM Convergence Layer. The experimental results show that the DTN NORM Convergence Layer exhibits better performance than TCP/IP, and appears to perform better over difficult radio links

An Evaluation of Protocols for UAV Science Applications

This paper identifies data transport needs for current and future science payloads deployed on the NASA Global Hawk Unmanned Aeronautical Vehicle (UAV). The NASA Global Hawk communication system and operational constrains are presented. The Genesis and Rapid Intensification Processes (GRIP) mission is used to provide the baseline communication requirements as a variety of payloads were utilized in this mission. User needs and desires are addressed. Protocols are matched to the payload needs and an evaluation of various techniques and tradeoffs are presented. Such techniques include utilization rate-base selective negative acknowledgement protocols and possible use of protocol enhancing proxies. Tradeoffs of communication architectures that address ease-of-use and security considerations are also presented

A further comparison of different TCP/IP and DTN protocols over the D-STAR Digital Data mode

This work examines the performance of the Digital Smart Technologies for Amateur Radio - Digital Data mode with various IP and non-IP based protocols. A throughput comparison was performed between TCP/IP and two DTN convergence Layers. The experimental results show that the DTN NORM Convergence Layer exhibits better performance than TCP/IP and TCP based convergence layers, and, furthermore appears to be more suited for use on difficult radio links

Simple Low-Density Parity Check (LDPC) Staircase Forward Error Correction (FEC) Scheme for FECFRAME, RFC 6816

This document describes a fully specified simple Forward Error Correction (FEC) scheme for Low-Density Parity Check (LDPC) Staircase codes that can be used to protect media streams along the lines defined by FECFRAME. These codes have many interesting properties: they are systematic codes, they perform close to ideal codes in many use-cases, and they also feature very high encoding and decoding throughputs. LDPC-Staircase codes are therefore a good solution to protect a single high bitrate source flow or to protect globally several mid-rate flows within a single FECFRAME instance. They are also a good solution whenever the processing load of a software encoder or decoder must be kept to a minimum