Display walls made from multiple monitors are often used when very high resolution images are req... more 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.
Active measurements, examine the capabilities of networks and the internet. Through the network a... more Active measurements, examine the capabilities of networks and the internet. Through the network analysis infrastructure (NAI), these measurements can provide useful data for network analysis. The National Laboratory for Applied Network Research (NLANR) team, has developed data sets which allow identifcation of a variety of problems which range from High Performance Connectivity and Commodity Network issues. to network hardware and routing issues. We present the steps necessary to secure and analyze such data. Figure 7-2: Routing information for forward and reverse path connections between SDSC and WUSTL.
Wireless sensor networks and methods of developing user applications is an active research area w... more Wireless sensor networks and methods of developing user applications is an active research area with several unique challenges. In this paper we first present an overview of the current programming approaches. We then describe a system under development that adapts techniques from the distributed operating systems world to create a new method of programming wireless sensor networks.
Obtaining good performance from WWW proxy caches is critically dependent on the document replacem... more Obtaining good performance from WWW proxy caches is critically dependent on the document replacement policy used by the proxy. This paper validates the work of other authors by reproducing their studies of proxy cache document replacement algorithms. From this basis a cross-trace study is mounted. This demonstrates that the performance of most document replacement algorithms is dependent on the type of workload that they are presented with. Finally we propose a new algorithm, LRU*, that consistently performs well across all our traces.
Over recent years the size and capacity of the Internet has continued its exponential growth driv... more Over recent years the size and capacity of the Internet has continued its exponential growth driven by new applications and improving network technology. These changes are particularly significant in the New Zealand context where the high costs of trans-Pacific traffic has mandated that traffic be charged for by volume. This has also lead to a significant focus within the New Zealand Internet community on issues of caching and of careful planning for capacity. Approximately three years ago the WAND research group began with a program to measure ATM traffic. We were sharply constrained by cost and decided to start by reprogramming some ATM NIC cards. This paper is largely based on our experience as we have broadened this work to include IP-based non-ATM networks and the construction of our own hardware. We have learned a number of lessons in this work, rediscovering along the way some of the hard discipline that all observation scientists must submit to.
This report gives an overview of the current research and trends in the area of TCP/IP security. ... more This report gives an overview of the current research and trends in the area of TCP/IP security. The basic issues in network security and encryption techniques are presented as background material. The leading contenders in the the area of secure Internet protocols are then reviewed. The review includes the security architecture proposed in the draft standard for the next version of the Internet protocol (IPv6). Issues in key management for the encryption and message digests employed in IP security architectures are presented with a brief overview of the ANSI X9.17 standard and the use of key management protocols in SNMP and Kerberos. Finally, an overview of possible implementation scenarios for IP security are presented,.
Eurographics Workshop on Parallel Graphics and Visualization, 2011
Display walls made from multiple monitors are often used when very high resolution images are req... more 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.
The growth of the Internet is placing strain on the world wide telecommunications infrastructure.... more The growth of the Internet is placing strain on the world wide telecommunications infrastructure. In particular it is no longer possible to purchase capacity on terrestrial cables to some parts of the world. To meet the growing traffic needs of the Internet some Network Service Providers are deploying asymmetric satellite connections. These providers must choose an architecture for the international component of the network. Depending on the architecture chosen the traffic on the international circuit might be made up of a large number of independent connections or a smaller number of connections carrying aggregated traffic. The appropriate approach is not immediately apparent because there are opposing performance factors and because the effect of asymmetric delay on TCP performance is not well understood.
The graphs to the left show the first second of slow start and connection establishment measured ... more The graphs to the left show the first second of slow start and connection establishment measured on the sender side with a 2Mb/s link and a round trip time of 200ms. The sender and receiver computers each have the same operating system installed.
The TCP models in ns-2 have been validated and are widely used in network research. They are howe... more The TCP models in ns-2 have been validated and are widely used in network research. They are however not aimed at producing results consistent with a TCP implementation, they are rather designed to be a general model for TCP congestion control. The Network Simulation Cradle makes real world TCP implementations available to ns-2: Linux, FreeBSD and OpenBSD can all be simulated as easily as using the original simplified models. These simulated TCP implementations can be validated by directly comparing packet traces from simulations to traces measured from a real network. We describe the Network Simulation Cradle, present packet trace comparison results showing the high degree of accuracy possible when simulating with real TCP implementations and briefly show how this is reflected in a simulation study of TCP throughput.
2010 Fourth International Conference on Sensor Technologies and Applications, 2010
AbstractObject migration in wireless sensor networks has the potential to reduce energy consumpt... more AbstractObject migration in wireless sensor networks has the potential to reduce energy consumption for a wireless sensor network mesh. Automated migration reduces the need for the programmer to perform manual static analysis to find an efficient layout solution. Instead, the system ...
Proceedings of the First ACM SIGCOMM Workshop on Internet Measurement Workshop - IMW '01, 2001
Packet probing is an important Internet measurement technique, supporting the investigation of pa... more Packet probing is an important Internet measurement technique, supporting the investigation of packet delay, path, and loss. Current packet probing techniques use Internet Protocols such as the Internet Control Message Protocol (ICMP), the User Datagram Protocol (UDP), and the Transmission Control Protocol (TCP). These protocols were not originally designed for measurement purposes. Current packet probing techniques have several limitations that can be avoided. The IP Measurement Protocol (IPMP) is presented as a protocol that addresses several of the limitations discussed.
Packet header traces are widely used in network analysis. Header traces are the aggregate of traf... more Packet header traces are widely used in network analysis. Header traces are the aggregate of traffic from many concurrent applications. We present a methodology, based on machine learning, that can break the trace down into clusters of traffic where each cluster has different traffic characteristics. Typical clusters include bulk transfer, single and multiple transactions and interactive traffic, amongst others. The paper includes a description of the methodology, a visualisation of the attribute statistics that aids in recognising cluster types and a discussion of the stability and effectiveness of the methodology.
Many existing systems are written in C and are not re-entrant or thread safe. Sometimes these sys... more Many existing systems are written in C and are not re-entrant or thread safe. Sometimes these systems are required in a context for which they were not first designed, possibly meaning they now need to be re-entrant. This article introduces a program that filters C source code, modifying shared resources (the global variables) to make the code re-entrant: 'virtualizing' the code. The code is then compiled as normal. This approach allows programmatic virtualization with little cost at runtime.
Wireless sensor networks and methods of developing user applications is an active research area w... more Wireless sensor networks and methods of developing user applications is an active research area with several unique challenges. In this paper we first present an overview of the current programming approaches. We then describe a system under development that adapts techniques from the distributed operating systems world to create a new method of programming wireless sensor networks.
Network simulation is used widely in network research to test new protocols, modifications to exi... more Network simulation is used widely in network research to test new protocols, modifications to existing protocols and new ideas. The tool used in many cases is ns-2. The nature of the ns-2 protocols means that they are often based on theoretical models that ...
3/27/2000: This work is an Authors' version, and has been submitted for publication. Copyrig... more 3/27/2000: This work is an Authors' version, and has been submitted for publication. Copyright may be transferred without further notice and the accepted version may then be posted by the publisher. ... Todd Hansen 1 Jose Otero 1 Tony McGregor 2 Hans-Werner Braun 1
This paper presents the comparison of two methods of system monitoring, passive network monitorin... more This paper presents the comparison of two methods of system monitoring, passive network monitoring and kernel instrumentation. The comparison is made on the basis of passive network monitoring being used as a replacement for kernel instrumentation in some situations. Despite the fact that the passive network monitoring technique is shown to perform poorly as a direct replacement for kernel instrumentation, this paper indicates the areas where passive network monitoring could be used to the greatest advantage and ...
Display walls made from multiple monitors are often used when very high resolution images are req... more 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.
Active measurements, examine the capabilities of networks and the internet. Through the network a... more Active measurements, examine the capabilities of networks and the internet. Through the network analysis infrastructure (NAI), these measurements can provide useful data for network analysis. The National Laboratory for Applied Network Research (NLANR) team, has developed data sets which allow identifcation of a variety of problems which range from High Performance Connectivity and Commodity Network issues. to network hardware and routing issues. We present the steps necessary to secure and analyze such data. Figure 7-2: Routing information for forward and reverse path connections between SDSC and WUSTL.
Wireless sensor networks and methods of developing user applications is an active research area w... more Wireless sensor networks and methods of developing user applications is an active research area with several unique challenges. In this paper we first present an overview of the current programming approaches. We then describe a system under development that adapts techniques from the distributed operating systems world to create a new method of programming wireless sensor networks.
Obtaining good performance from WWW proxy caches is critically dependent on the document replacem... more Obtaining good performance from WWW proxy caches is critically dependent on the document replacement policy used by the proxy. This paper validates the work of other authors by reproducing their studies of proxy cache document replacement algorithms. From this basis a cross-trace study is mounted. This demonstrates that the performance of most document replacement algorithms is dependent on the type of workload that they are presented with. Finally we propose a new algorithm, LRU*, that consistently performs well across all our traces.
Over recent years the size and capacity of the Internet has continued its exponential growth driv... more Over recent years the size and capacity of the Internet has continued its exponential growth driven by new applications and improving network technology. These changes are particularly significant in the New Zealand context where the high costs of trans-Pacific traffic has mandated that traffic be charged for by volume. This has also lead to a significant focus within the New Zealand Internet community on issues of caching and of careful planning for capacity. Approximately three years ago the WAND research group began with a program to measure ATM traffic. We were sharply constrained by cost and decided to start by reprogramming some ATM NIC cards. This paper is largely based on our experience as we have broadened this work to include IP-based non-ATM networks and the construction of our own hardware. We have learned a number of lessons in this work, rediscovering along the way some of the hard discipline that all observation scientists must submit to.
This report gives an overview of the current research and trends in the area of TCP/IP security. ... more This report gives an overview of the current research and trends in the area of TCP/IP security. The basic issues in network security and encryption techniques are presented as background material. The leading contenders in the the area of secure Internet protocols are then reviewed. The review includes the security architecture proposed in the draft standard for the next version of the Internet protocol (IPv6). Issues in key management for the encryption and message digests employed in IP security architectures are presented with a brief overview of the ANSI X9.17 standard and the use of key management protocols in SNMP and Kerberos. Finally, an overview of possible implementation scenarios for IP security are presented,.
Eurographics Workshop on Parallel Graphics and Visualization, 2011
Display walls made from multiple monitors are often used when very high resolution images are req... more 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.
The growth of the Internet is placing strain on the world wide telecommunications infrastructure.... more The growth of the Internet is placing strain on the world wide telecommunications infrastructure. In particular it is no longer possible to purchase capacity on terrestrial cables to some parts of the world. To meet the growing traffic needs of the Internet some Network Service Providers are deploying asymmetric satellite connections. These providers must choose an architecture for the international component of the network. Depending on the architecture chosen the traffic on the international circuit might be made up of a large number of independent connections or a smaller number of connections carrying aggregated traffic. The appropriate approach is not immediately apparent because there are opposing performance factors and because the effect of asymmetric delay on TCP performance is not well understood.
The graphs to the left show the first second of slow start and connection establishment measured ... more The graphs to the left show the first second of slow start and connection establishment measured on the sender side with a 2Mb/s link and a round trip time of 200ms. The sender and receiver computers each have the same operating system installed.
The TCP models in ns-2 have been validated and are widely used in network research. They are howe... more The TCP models in ns-2 have been validated and are widely used in network research. They are however not aimed at producing results consistent with a TCP implementation, they are rather designed to be a general model for TCP congestion control. The Network Simulation Cradle makes real world TCP implementations available to ns-2: Linux, FreeBSD and OpenBSD can all be simulated as easily as using the original simplified models. These simulated TCP implementations can be validated by directly comparing packet traces from simulations to traces measured from a real network. We describe the Network Simulation Cradle, present packet trace comparison results showing the high degree of accuracy possible when simulating with real TCP implementations and briefly show how this is reflected in a simulation study of TCP throughput.
2010 Fourth International Conference on Sensor Technologies and Applications, 2010
AbstractObject migration in wireless sensor networks has the potential to reduce energy consumpt... more AbstractObject migration in wireless sensor networks has the potential to reduce energy consumption for a wireless sensor network mesh. Automated migration reduces the need for the programmer to perform manual static analysis to find an efficient layout solution. Instead, the system ...
Proceedings of the First ACM SIGCOMM Workshop on Internet Measurement Workshop - IMW '01, 2001
Packet probing is an important Internet measurement technique, supporting the investigation of pa... more Packet probing is an important Internet measurement technique, supporting the investigation of packet delay, path, and loss. Current packet probing techniques use Internet Protocols such as the Internet Control Message Protocol (ICMP), the User Datagram Protocol (UDP), and the Transmission Control Protocol (TCP). These protocols were not originally designed for measurement purposes. Current packet probing techniques have several limitations that can be avoided. The IP Measurement Protocol (IPMP) is presented as a protocol that addresses several of the limitations discussed.
Packet header traces are widely used in network analysis. Header traces are the aggregate of traf... more Packet header traces are widely used in network analysis. Header traces are the aggregate of traffic from many concurrent applications. We present a methodology, based on machine learning, that can break the trace down into clusters of traffic where each cluster has different traffic characteristics. Typical clusters include bulk transfer, single and multiple transactions and interactive traffic, amongst others. The paper includes a description of the methodology, a visualisation of the attribute statistics that aids in recognising cluster types and a discussion of the stability and effectiveness of the methodology.
Many existing systems are written in C and are not re-entrant or thread safe. Sometimes these sys... more Many existing systems are written in C and are not re-entrant or thread safe. Sometimes these systems are required in a context for which they were not first designed, possibly meaning they now need to be re-entrant. This article introduces a program that filters C source code, modifying shared resources (the global variables) to make the code re-entrant: 'virtualizing' the code. The code is then compiled as normal. This approach allows programmatic virtualization with little cost at runtime.
Wireless sensor networks and methods of developing user applications is an active research area w... more Wireless sensor networks and methods of developing user applications is an active research area with several unique challenges. In this paper we first present an overview of the current programming approaches. We then describe a system under development that adapts techniques from the distributed operating systems world to create a new method of programming wireless sensor networks.
Network simulation is used widely in network research to test new protocols, modifications to exi... more Network simulation is used widely in network research to test new protocols, modifications to existing protocols and new ideas. The tool used in many cases is ns-2. The nature of the ns-2 protocols means that they are often based on theoretical models that ...
3/27/2000: This work is an Authors' version, and has been submitted for publication. Copyrig... more 3/27/2000: This work is an Authors' version, and has been submitted for publication. Copyright may be transferred without further notice and the accepted version may then be posted by the publisher. ... Todd Hansen 1 Jose Otero 1 Tony McGregor 2 Hans-Werner Braun 1
This paper presents the comparison of two methods of system monitoring, passive network monitorin... more This paper presents the comparison of two methods of system monitoring, passive network monitoring and kernel instrumentation. The comparison is made on the basis of passive network monitoring being used as a replacement for kernel instrumentation in some situations. Despite the fact that the passive network monitoring technique is shown to perform poorly as a direct replacement for kernel instrumentation, this paper indicates the areas where passive network monitoring could be used to the greatest advantage and ...
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Papers by Tony McGregor