Emerging service grids are being challenged by an increasing number of jobs, larger job sizes, th... more Emerging service grids are being challenged by an increasing number of jobs, larger job sizes, the demand for more storage and computational resources, and ever-rising bandwidth and latency requirements. A specific case of these grids, designed to administer highly demanding media applications (including media production environments) are the so-called media grids. Even though optical networking is the apparent technology of
Parallel and Distributed Processing Techniques and Applications, 2007
... have determined the required cache capacities at each level of the tree network based on ... ... more ... have determined the required cache capacities at each level of the tree network based on ... 4 vv iisiriimtiji ¡He тип deployed on an existing set of desktop PCs", ACM ... 11] Kangasharju, 1, Roberts, J., Ross, K., "Object replication strategies in content distribution networks", Computer ...
12th IFIP/IEEE International Symposium on Integrated Network Management (IM 2011) and Workshops, 2011
In recent years, telecom operators have been moving away from traditional, broadcast-driven, tele... more In recent years, telecom operators have been moving away from traditional, broadcast-driven, television towards IPbased, interactive and on-demand services. Consequently, multicast is no longer a viable solution to limit the amount of traffic in the IP-TV network. In order to counter an explosion in generated traffic, caches can be strategically placed throughout the content delivery infrastructure. As the size of caches is usually limited to only a small fraction of the total size of all content items, it is important to accurately predict future content popularity. Classical caching strategies only take into account the past when deciding what content to cache. Recently, a trend towards novel strategies that actually try to predict future content popularity has arisen. In this paper, we ascertain the viability of using popularity prediction in realistic multimedia content caching scenarios. The use of popularity prediction is compared to classical strategies using trace files from an actual deployed Video on Demand service. Additionally, the synergy between several parameters, such as cache size and prediction window, is investigated.
2009 First International Conference on Advances in P2P Systems, 2009
Resource discovery is an important aspect of many modern large-scale distributed systems. In the ... more Resource discovery is an important aspect of many modern large-scale distributed systems. In the past, this problem has been solved using many different approaches, such as a central registry server, flooding-based protocols, and distributed hash tables. In this paper, these three widely used architectures are compared, using measurement results obtained from real implementations run on an Emulab emulation environment. This allows us to study the advantages and disadvantages of the architectures and determine their usefulness.
Due to overprovisioning of infrastructure nodes in overlay networks, many nodes remain idle at ti... more Due to overprovisioning of infrastructure nodes in overlay networks, many nodes remain idle at times of low network load. Some of these nodes could be temporary removed from the overlay topology and could then be used for other purposes or alternatively be temporarily shut down, to save energy. In this paper we present several algorithms to select the subset of overlay nodes that should be part of the overlay topology. This decision is made based on the current and (estimated) future network load and the locality of the clients and servers connected to the overlay network. As network load or conditions change, additional nodes can be dynamically (de)activated. Our algorithms can be used in conjunction with existing overlay topology construction protocols. Through extensive simulations, we have evaluated and compared the performance of our algorithms.
2008 Fourth Advanced International Conference on Telecommunications, 2008
Currently many service providers offer their services using a private and proprietary hard-and so... more Currently many service providers offer their services using a private and proprietary hard-and software infrastructure. These infrastructures often share many similarities. Hence we believe a generic service delivery architecture, that allows service providers to offer a large array of different services on a shared infrastructure, would provide many advantages over current silo-based approaches.
2009 IFIP/IEEE International Symposium on Integrated Network Management, 2009
A generic and self-managing service hosting infrastructure, provides a means to offer a large var... more A generic and self-managing service hosting infrastructure, provides a means to offer a large variety of services to users across the Internet. Such an infrastructure provides mechanisms to automatically allocate resources to services, discover the location of these services, and route client requests to a suitable service instance.
2009 First International Conference on Advances in P2P Systems, 2009
Today's trend is to create and share personal content, such as music files, digital photos and di... more Today's trend is to create and share personal content, such as music files, digital photos and digital movies. The result is an explosive growth of a user's personal content archive. Managing such an often distributed collection becomes a complex and time consuming task, which indicates the need for a personal content management system that provides storage space transparently, is quality-aware, and is available at any time and at any place to end-users. A solution that fulfills this need is a Personal Content Storage Service (PCSS). A key feature of a PCSS is the ability to search worldwide through the dataset of personal files. Due to the extremely large size of the dataset of personal content, a centralized approach is no longer feasible; therefore the PCSS uses a structured peer-to-peer network: the Distributed Hash DHT). In order to further increase the lookup performance, a caching layer is used between the application layer and the DHT. In this article we present the caching layer and introduce the Request Times Distance (RTD) caching algorithm, which uses popularity and distance metrics to increase the lookup performance. By extending the RTD algorithm with a sliding window and cooperative caching, a more efficient solution than standard algorithms is obtained. The cooperative RTD caching algorithm is evaluated using the PlanetSim simulation framework and shows a performance increase of up to 16% compared to the Least Frequently Used (LFU) caching algorithm.
2009 IFIP/IEEE International Symposium on Integrated Network Management-Workshops, 2009
Multimedia content sharing services, such as YouTube, usually offer only low quality video stream... more Multimedia content sharing services, such as YouTube, usually offer only low quality video streams. Additionally, it is expected the popularity of these services will increase even further in the future. Therefore, current streamingcontent delivery architectures, with centralised searching and management components, might not be able to keep up with the ever-growing user bases.
Today's trend to create and share personal content, such as digital photos and digital movies, re... more Today's trend to create and share personal content, such as digital photos and digital movies, results in an explosive growth of a user's personal content archive. Managing such an often distributed collection becomes a complex and time consuming task, indicating the need for a personal content management system that provides storage space transparently, is quality-aware, and is available at any time and at any place to end-users. A key feature of such a Personal Content Storage Service (PCSS) is the ability to search worldwide through the dataset of personal files. Due to the extremely large size of the dataset of personal content, a centralized solution is no longer feasible and an interesting approach for an efficient distributed PCSS implementation is to use a structured peer-topeer network, and more in particular a Distributed Hash Table (DHT), providing a logarithmic lookup performance in the number of network nodes. In order to further increase the lookup performance, a caching layer is typically used between the application layer and the DHT. These caching strategies are location neutral, and usually do not exploit location dependence of request patterns. In this article we present our cooperative caching framework and introduce the cooperative Request Times Distance (RTD) caching algorithm. Since, lookup patterns in a PCSS typically have a power law popularity distribution and exhibit location dependent requests patterns, the proposed caching solution takes into account popularity and distance metrics. To enable cooperation between caches we introduce an update protocol, which only occasionally introduces one hop delay for a lookup operation. We present a systematic analysis of the caching framework and compare the cooperative caching algorithm to the state-of-theart Beehive replication strategy. The cooperative RTD caching solution shows that when request patterns are more localized, the increase in lookup performance through cooperation is significantly better than Beehive.
The recent introduction of Content Distribution Networks (CDNs) enhances the delivery of high qua... more The recent introduction of Content Distribution Networks (CDNs) enhances the delivery of high quality multimedia content to end users. In a CDN architecture, the content is replicated to so-called surrogate servers, generally at the edge of the transport network, to improve the quality of service (QoS) of streaming multimedia delivery services. By using peer-to-peer (P2P) technologies, these edge servers can co-operate and provide a more scalable and robust service in a self-organizing CDN.
The FP7 OCEAN project investigates scalable content and network mechanisms to deliver multimedia ... more The FP7 OCEAN project investigates scalable content and network mechanisms to deliver multimedia services with high quality over a Content Delivery Network (CDN) deployed in the last mile. To evaluate the solutions proposed by OCEAN, a three step approach was taken in which the solutions were first simulated, later emulated and ultimately deployed in a field trial. In this article, we focus on the emulation of OCEAN components on the iLab.t Virtual Wall. We discuss the benefit of performing emulations, both for the simulations and field trial, through some specific illustrative OCEAN examples.
Emerging service grids are being challenged by an increasing number of jobs, larger job sizes, th... more Emerging service grids are being challenged by an increasing number of jobs, larger job sizes, the demand for more storage and computational resources, and ever-rising bandwidth and latency requirements. A specific case of these grids, designed to administer highly demanding media applications (including media production environments) are the so-called media grids. Even though optical networking is the apparent technology of
Parallel and Distributed Processing Techniques and Applications, 2007
... have determined the required cache capacities at each level of the tree network based on ... ... more ... have determined the required cache capacities at each level of the tree network based on ... 4 vv iisiriimtiji ¡He тип deployed on an existing set of desktop PCs", ACM ... 11] Kangasharju, 1, Roberts, J., Ross, K., "Object replication strategies in content distribution networks", Computer ...
12th IFIP/IEEE International Symposium on Integrated Network Management (IM 2011) and Workshops, 2011
In recent years, telecom operators have been moving away from traditional, broadcast-driven, tele... more In recent years, telecom operators have been moving away from traditional, broadcast-driven, television towards IPbased, interactive and on-demand services. Consequently, multicast is no longer a viable solution to limit the amount of traffic in the IP-TV network. In order to counter an explosion in generated traffic, caches can be strategically placed throughout the content delivery infrastructure. As the size of caches is usually limited to only a small fraction of the total size of all content items, it is important to accurately predict future content popularity. Classical caching strategies only take into account the past when deciding what content to cache. Recently, a trend towards novel strategies that actually try to predict future content popularity has arisen. In this paper, we ascertain the viability of using popularity prediction in realistic multimedia content caching scenarios. The use of popularity prediction is compared to classical strategies using trace files from an actual deployed Video on Demand service. Additionally, the synergy between several parameters, such as cache size and prediction window, is investigated.
2009 First International Conference on Advances in P2P Systems, 2009
Resource discovery is an important aspect of many modern large-scale distributed systems. In the ... more Resource discovery is an important aspect of many modern large-scale distributed systems. In the past, this problem has been solved using many different approaches, such as a central registry server, flooding-based protocols, and distributed hash tables. In this paper, these three widely used architectures are compared, using measurement results obtained from real implementations run on an Emulab emulation environment. This allows us to study the advantages and disadvantages of the architectures and determine their usefulness.
Due to overprovisioning of infrastructure nodes in overlay networks, many nodes remain idle at ti... more Due to overprovisioning of infrastructure nodes in overlay networks, many nodes remain idle at times of low network load. Some of these nodes could be temporary removed from the overlay topology and could then be used for other purposes or alternatively be temporarily shut down, to save energy. In this paper we present several algorithms to select the subset of overlay nodes that should be part of the overlay topology. This decision is made based on the current and (estimated) future network load and the locality of the clients and servers connected to the overlay network. As network load or conditions change, additional nodes can be dynamically (de)activated. Our algorithms can be used in conjunction with existing overlay topology construction protocols. Through extensive simulations, we have evaluated and compared the performance of our algorithms.
2008 Fourth Advanced International Conference on Telecommunications, 2008
Currently many service providers offer their services using a private and proprietary hard-and so... more Currently many service providers offer their services using a private and proprietary hard-and software infrastructure. These infrastructures often share many similarities. Hence we believe a generic service delivery architecture, that allows service providers to offer a large array of different services on a shared infrastructure, would provide many advantages over current silo-based approaches.
2009 IFIP/IEEE International Symposium on Integrated Network Management, 2009
A generic and self-managing service hosting infrastructure, provides a means to offer a large var... more A generic and self-managing service hosting infrastructure, provides a means to offer a large variety of services to users across the Internet. Such an infrastructure provides mechanisms to automatically allocate resources to services, discover the location of these services, and route client requests to a suitable service instance.
2009 First International Conference on Advances in P2P Systems, 2009
Today's trend is to create and share personal content, such as music files, digital photos and di... more Today's trend is to create and share personal content, such as music files, digital photos and digital movies. The result is an explosive growth of a user's personal content archive. Managing such an often distributed collection becomes a complex and time consuming task, which indicates the need for a personal content management system that provides storage space transparently, is quality-aware, and is available at any time and at any place to end-users. A solution that fulfills this need is a Personal Content Storage Service (PCSS). A key feature of a PCSS is the ability to search worldwide through the dataset of personal files. Due to the extremely large size of the dataset of personal content, a centralized approach is no longer feasible; therefore the PCSS uses a structured peer-to-peer network: the Distributed Hash DHT). In order to further increase the lookup performance, a caching layer is used between the application layer and the DHT. In this article we present the caching layer and introduce the Request Times Distance (RTD) caching algorithm, which uses popularity and distance metrics to increase the lookup performance. By extending the RTD algorithm with a sliding window and cooperative caching, a more efficient solution than standard algorithms is obtained. The cooperative RTD caching algorithm is evaluated using the PlanetSim simulation framework and shows a performance increase of up to 16% compared to the Least Frequently Used (LFU) caching algorithm.
2009 IFIP/IEEE International Symposium on Integrated Network Management-Workshops, 2009
Multimedia content sharing services, such as YouTube, usually offer only low quality video stream... more Multimedia content sharing services, such as YouTube, usually offer only low quality video streams. Additionally, it is expected the popularity of these services will increase even further in the future. Therefore, current streamingcontent delivery architectures, with centralised searching and management components, might not be able to keep up with the ever-growing user bases.
Today's trend to create and share personal content, such as digital photos and digital movies, re... more Today's trend to create and share personal content, such as digital photos and digital movies, results in an explosive growth of a user's personal content archive. Managing such an often distributed collection becomes a complex and time consuming task, indicating the need for a personal content management system that provides storage space transparently, is quality-aware, and is available at any time and at any place to end-users. A key feature of such a Personal Content Storage Service (PCSS) is the ability to search worldwide through the dataset of personal files. Due to the extremely large size of the dataset of personal content, a centralized solution is no longer feasible and an interesting approach for an efficient distributed PCSS implementation is to use a structured peer-topeer network, and more in particular a Distributed Hash Table (DHT), providing a logarithmic lookup performance in the number of network nodes. In order to further increase the lookup performance, a caching layer is typically used between the application layer and the DHT. These caching strategies are location neutral, and usually do not exploit location dependence of request patterns. In this article we present our cooperative caching framework and introduce the cooperative Request Times Distance (RTD) caching algorithm. Since, lookup patterns in a PCSS typically have a power law popularity distribution and exhibit location dependent requests patterns, the proposed caching solution takes into account popularity and distance metrics. To enable cooperation between caches we introduce an update protocol, which only occasionally introduces one hop delay for a lookup operation. We present a systematic analysis of the caching framework and compare the cooperative caching algorithm to the state-of-theart Beehive replication strategy. The cooperative RTD caching solution shows that when request patterns are more localized, the increase in lookup performance through cooperation is significantly better than Beehive.
The recent introduction of Content Distribution Networks (CDNs) enhances the delivery of high qua... more The recent introduction of Content Distribution Networks (CDNs) enhances the delivery of high quality multimedia content to end users. In a CDN architecture, the content is replicated to so-called surrogate servers, generally at the edge of the transport network, to improve the quality of service (QoS) of streaming multimedia delivery services. By using peer-to-peer (P2P) technologies, these edge servers can co-operate and provide a more scalable and robust service in a self-organizing CDN.
The FP7 OCEAN project investigates scalable content and network mechanisms to deliver multimedia ... more The FP7 OCEAN project investigates scalable content and network mechanisms to deliver multimedia services with high quality over a Content Delivery Network (CDN) deployed in the last mile. To evaluate the solutions proposed by OCEAN, a three step approach was taken in which the solutions were first simulated, later emulated and ultimately deployed in a field trial. In this article, we focus on the emulation of OCEAN components on the iLab.t Virtual Wall. We discuss the benefit of performing emulations, both for the simulations and field trial, through some specific illustrative OCEAN examples.
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Papers by Tim Wauters