2005
Conference article
Restricted
Resource partitioning and call admission control in a rain faded satellite channel with real-time connections
Gotta A
The paper aims at devising a control system for dynamic resource allocation in a multi-service satellite network with real-time and streaming connections. A Master Station adaptively partitions the overall satellite capacity among the earth stations, according to their traffic load and fading conditions. Within the bandwidth temporarily assigned, the stations independently perform Call Admission Control (CAC) of real-time connection requests and assign the proper redundancy to overcome the fading effects. Thus, there is a double cross-layer interaction between the physical and data link layers, whereby the fading severity plays a role in the overall bandwidth allocation. The performance of the method is analyzed by simulation, under a realistic link budget and real fading patterns.
Gotta A
The paper aims at devising a control system for dynamic resource allocation in a multi-service satellite network with real-time and streaming connections. A Master Station adaptively partitions the overall satellite capacity among the earth stations, according to their traffic load and fading conditions. Within the bandwidth temporarily assigned, the stations independently perform Call Admission Control (CAC) of real-time connection requests and assign the proper redundancy to overcome the fading effects. Thus, there is a double cross-layer interaction between the physical and data link layers, whereby the fading severity plays a role in the overall bandwidth allocation. The performance of the method is analyzed by simulation, under a realistic link budget and real fading patterns.
2003
Conference article
Restricted
Derivative estimation and optimization of loss probability in satellite packet networks
Canesi S, Gotta A, Davoli F, Marchese M, Mongelli M
In this paper we consider a resource allocation problem for a satellite network. Since thecapacity of the system is finite and divided in finite portions, the resource allocation problem reveals to be a discrete stochastic programming problem, which is typically NP-Hard. We propose a new approachbased on the minimization over a discrete constraint set using an estimation of the gradient, obtained through a 'relaxed continuous extension' of the performance measure. The computation of the gradientestimation is based on the Infinitesimal Perturbation Analysis (IPA) technique, applied on a Stochastic Fluid Model (SFM) of the network. Neither closed forms of the performance measures, nor additionalfeedbacks concerning the state of the system and very mild assumptions on the probabilistic properties about the statistical processes involved in the problem are requested.
Canesi S, Gotta A, Davoli F, Marchese M, Mongelli M
In this paper we consider a resource allocation problem for a satellite network. Since thecapacity of the system is finite and divided in finite portions, the resource allocation problem reveals to be a discrete stochastic programming problem, which is typically NP-Hard. We propose a new approachbased on the minimization over a discrete constraint set using an estimation of the gradient, obtained through a 'relaxed continuous extension' of the performance measure. The computation of the gradientestimation is based on the Infinitesimal Perturbation Analysis (IPA) technique, applied on a Stochastic Fluid Model (SFM) of the network. Neither closed forms of the performance measures, nor additionalfeedbacks concerning the state of the system and very mild assumptions on the probabilistic properties about the statistical processes involved in the problem are requested.
2007
Conference article
Restricted
Advanced satellite infrastructures in future global Grid computing: network solutions to compensate delivery delay
Bonito B, Gotta A, Secchi R
Scientific equipments in remote locations are often integrated in a Grid network by means of satellite links. When the Grid is an Internet overlay network, TCP-like congestion control protocols tend to introduce large delays and to achieve poor bandwidth utilization during the startup phase due to the large bandwidth-delay product of the satellite link. Recent studies demonstrate that the loss of performance is high when a demand assignment multiple access (DAMA) scheme is adopted to manage satellite resources. To overcome this problem, we propose a new mechanism based on Quick Start, a recent IETF recommendation, to enhance the startup performance of data and streaming flows. We show, by means of extensive simulations, that our modifications to enable a QS based DAMA algorithm allow the initial end- to-end delay to be significantly reduced and the queue length in transmitting nodes stabilized. Moreover, our results point out that the startup delay is quite independent of the flow rate, which makes this algorithm suitable to the high bitrate required by Grid computing applications.
Bonito B, Gotta A, Secchi R
Scientific equipments in remote locations are often integrated in a Grid network by means of satellite links. When the Grid is an Internet overlay network, TCP-like congestion control protocols tend to introduce large delays and to achieve poor bandwidth utilization during the startup phase due to the large bandwidth-delay product of the satellite link. Recent studies demonstrate that the loss of performance is high when a demand assignment multiple access (DAMA) scheme is adopted to manage satellite resources. To overcome this problem, we propose a new mechanism based on Quick Start, a recent IETF recommendation, to enhance the startup performance of data and streaming flows. We show, by means of extensive simulations, that our modifications to enable a QS based DAMA algorithm allow the initial end- to-end delay to be significantly reduced and the queue length in transmitting nodes stabilized. Moreover, our results point out that the startup delay is quite independent of the flow rate, which makes this algorithm suitable to the high bitrate required by Grid computing applications.
2009
Contribution to book
Restricted
Advanced satellite infrastructures in future global grid computing: network solutions to compensate delivery delay
Bonito A B, Gotta A, Secchi R
Scientific equipment in remote locations may be integrated in a Grid network by means of satellite links. When the Grid is an Internet overlay network, TCP- like congestion control protocols tend to introduce large delays and to achieve poor bandwidth utilization during the startup phase due to the large bandwidth- delay product of the satellite link. Recent studies demonstrate that the loss of performance is high when a demand assignment multiple access (DAMA) scheme is adopted to manage satellite resources. To overcome this problem, we propose a new mechanism based on Quick Start, a recent IETF recommendation, to enhance the startup performance of data and streaming flows. We show, by means of extensive simulations, that our modifications to enable a QS based DAMA algorithm allow the initial end-to-end delay to be significantly reduced and the queue length in transmitting nodes stabilized. Moreover, our results point out that the startup delay is quite independent of the flow rate, which makes this algorithm suitable to the high bitrate required by Grid computing applications.
Bonito A B, Gotta A, Secchi R
Scientific equipment in remote locations may be integrated in a Grid network by means of satellite links. When the Grid is an Internet overlay network, TCP- like congestion control protocols tend to introduce large delays and to achieve poor bandwidth utilization during the startup phase due to the large bandwidth- delay product of the satellite link. Recent studies demonstrate that the loss of performance is high when a demand assignment multiple access (DAMA) scheme is adopted to manage satellite resources. To overcome this problem, we propose a new mechanism based on Quick Start, a recent IETF recommendation, to enhance the startup performance of data and streaming flows. We show, by means of extensive simulations, that our modifications to enable a QS based DAMA algorithm allow the initial end-to-end delay to be significantly reduced and the queue length in transmitting nodes stabilized. Moreover, our results point out that the startup delay is quite independent of the flow rate, which makes this algorithm suitable to the high bitrate required by Grid computing applications.
2007
Other
Open Access
State of the art in networks and grid infrastructures
Bonito B, Gotta A
In order to connect and access instruments located at various places on earth one needs a special grid infrastructure connected via high-speed, low-latency networks. The requirements of the network are dictated by the instruments themselves which are deployed within the grid. There are several possibilities how to achieve the desired properties of a network: Using special hardware, using the right protocols in the network protocol stack, and selecting appropriate middleware. All of these options will be discussed in this deliverable. There also exist several projects and testbeds related to the idea of remote instrumentation. This deliverable will have a look at the most important ones, in order to gain information which would otherwise not be possible to retrieve during RINGrid's short project lifetime.
Bonito B, Gotta A
In order to connect and access instruments located at various places on earth one needs a special grid infrastructure connected via high-speed, low-latency networks. The requirements of the network are dictated by the instruments themselves which are deployed within the grid. There are several possibilities how to achieve the desired properties of a network: Using special hardware, using the right protocols in the network protocol stack, and selecting appropriate middleware. All of these options will be discussed in this deliverable. There also exist several projects and testbeds related to the idea of remote instrumentation. This deliverable will have a look at the most important ones, in order to gain information which would otherwise not be possible to retrieve during RINGrid's short project lifetime.
See at:
CNR IRIS 
| ISTI Repository | CNR IRIS 
2007
Other
Open Access
Status of grid middleware and corresponding emerging standards for potential usage in sharing scientific instruments via (International) networks
Bonito B, Gotta A
Grid computing is a broadly accepted paradigm for sharing resources like processing power, or storage space. However, the grid is based on such a broad concept that it can do more than just integrating computing facilties. For example, it can be used to access expensive and thus not so easily available instruments. However, the middleware for instrument integration is not as well- polished as the middleware which is available for integrating computing facilities. This document gives an overview of the the solutions which are available, or are currently emerging, for remote instrumentation. Since remote instrumentation is a topic currently heavily under research, there are not many solutions available. Thus, this document concentrates on the solutions which are available, such as CIMA, as well as competing projects, such as GridCC. It also gives some use cases which help identify weak spots in the currently available technologies.
Bonito B, Gotta A
Grid computing is a broadly accepted paradigm for sharing resources like processing power, or storage space. However, the grid is based on such a broad concept that it can do more than just integrating computing facilties. For example, it can be used to access expensive and thus not so easily available instruments. However, the middleware for instrument integration is not as well- polished as the middleware which is available for integrating computing facilities. This document gives an overview of the the solutions which are available, or are currently emerging, for remote instrumentation. Since remote instrumentation is a topic currently heavily under research, there are not many solutions available. Thus, this document concentrates on the solutions which are available, such as CIMA, as well as competing projects, such as GridCC. It also gives some use cases which help identify weak spots in the currently available technologies.
See at:
CNR IRIS | ISTI Repository | CNR IRIS
2007
Other
Open Access
Summary of requirements and needs to be currently fulfilled to efficiently introduce the remote instrumentation idea into practice
Bonito B, Gotta A
This deliverable marks the end of a series of three deliverables. The three deliverables showed the reader what the state of the art in remote instrumentation middleware and networks currently is. While the second deliverable identified applications which benefit from remote instrumen- tation, this deliverable points out what prerequisites must be met in order to successfully convert these applications into remote instrumentation applications. Therefore, this deliverable serves as a basis for ongoing work regarding drafting a remote instrumentation architecture (WP6) as well for standardization efforts carried out by the RISGE (Remote Instrumentation Services in Grid Environments) research group which is currently established under the patronage of the OGF (Open Grid Forum).
Bonito B, Gotta A
This deliverable marks the end of a series of three deliverables. The three deliverables showed the reader what the state of the art in remote instrumentation middleware and networks currently is. While the second deliverable identified applications which benefit from remote instrumen- tation, this deliverable points out what prerequisites must be met in order to successfully convert these applications into remote instrumentation applications. Therefore, this deliverable serves as a basis for ongoing work regarding drafting a remote instrumentation architecture (WP6) as well for standardization efforts carried out by the RISGE (Remote Instrumentation Services in Grid Environments) research group which is currently established under the patronage of the OGF (Open Grid Forum).
See at:
CNR IRIS | ISTI Repository | CNR IRIS
2008
Other
Restricted
Quality of service and bandwidth allocation in Geo satellite networks: optimization and cross-layer design
Gotta A
Facoltà di Ingegneria Elettronica ed Informatica. Relatore: Davoli, Franco. Correlatori: Erina Ferro, Nedo Celandroni.
Gotta A
Facoltà di Ingegneria Elettronica ed Informatica. Relatore: Davoli, Franco. Correlatori: Erina Ferro, Nedo Celandroni.
2013
Other
Restricted
A TCP/IP satellite infrastructure for sensing operations in emergency contexts
Gotta A, Luglio M, Roseti C
The deployment of sensor networks for emergency management must be considered as an irreplaceable support for both monitoring and rescue activities. Depending on the scenario the use of satellite links as a segment of the network ensures connectivity where no other network is available and in some case can also provide an efficient and cost effective means to transfer data. This work aims to define architecture, to identify of optimum solution and to evaluate performance, in terms of throughput and service delay, when a protocol stack - from layer II to layer IV - is considered over a DVB-RCS system. The considered platform is composed of clusters of sensors (including low data rate devices and bulk data cameras) deployed over vast geographical areas, which collect on ground and distribute via satellite multimedia information, i.e. audio, video and sensed data, either for emergency or monitoring operations. A geostationary system was selected in order to guarantee high flexibility in terms of channel capacity. The proposed architecture assumes a session layer protocol, between the transport and application layers, which manages the multiplexing of streams coming from the input sources. The proposed architecture integrates wireless sensor networks and satellite networks, implying to approach technological issues from access layer up to transport and session layers, with heterogeneous traffic sources multiplexed by a satellite gateway, before being encapsulated into TCP/IP flows. Simulation results show the validity of the proposed architecture and protocol solutions.
Gotta A, Luglio M, Roseti C
The deployment of sensor networks for emergency management must be considered as an irreplaceable support for both monitoring and rescue activities. Depending on the scenario the use of satellite links as a segment of the network ensures connectivity where no other network is available and in some case can also provide an efficient and cost effective means to transfer data. This work aims to define architecture, to identify of optimum solution and to evaluate performance, in terms of throughput and service delay, when a protocol stack - from layer II to layer IV - is considered over a DVB-RCS system. The considered platform is composed of clusters of sensors (including low data rate devices and bulk data cameras) deployed over vast geographical areas, which collect on ground and distribute via satellite multimedia information, i.e. audio, video and sensed data, either for emergency or monitoring operations. A geostationary system was selected in order to guarantee high flexibility in terms of channel capacity. The proposed architecture assumes a session layer protocol, between the transport and application layers, which manages the multiplexing of streams coming from the input sources. The proposed architecture integrates wireless sensor networks and satellite networks, implying to approach technological issues from access layer up to transport and session layers, with heterogeneous traffic sources multiplexed by a satellite gateway, before being encapsulated into TCP/IP flows. Simulation results show the validity of the proposed architecture and protocol solutions.
2013
Other
Restricted
SatNEx III - State-of-the-art Web technologies and protocols
Secchi R, Gotta A, Roseti C, Collina M, Fairhurst G, Sun Zautoreihiliaffiliazione Altro
The new paradigm of web usage has motivated in recent years a series of proposals to update the standard Internet protocols related to web traffic. Some of these proposals provided suggestions to upgrade or even completely replace current Hypertext Transport Protocol (HTTP). Others, instead, focused on new TCP transport mechanisms (larger initial window, fast connection open, congestion window validation, tail loss probe, etc.) that are meant to accelerate the completion time of short data transfers. Web technologies are penetrating areas of computer-science before only the prerogative of dedicated computer systems, such as Cloud computing and Service-oriented applications. Web technologies are becoming increasingly prevalent as the delivery model for a wide range of applications, using methods such as Service-oriented architecture (SOA) or software as a service (SaaS). These methods implement the concept of ASP (application service provider) and on-demand computing software delivery: the provider hosts commercially available software and delivers copies of it over the Web, customising the software according to a client's needs. These changes are driving significant alterations in the traffic patterns generated by applications, but the impact of such changes are still uncertain. These changes are also set to change the requirements placed on a network - with an increasing emphasis on minimising web page download time, and an increasing need to consider on-off interactivity. The motivation for transport changes is a growing availability of high speed xDSL/cable access. These high-speed services differ from most wireless and satellite systems in key ways. Current wireless/satellite systems typically employ dynamic capacity schemes with protocol accelerators and access methods that have been tuned for the existing web traffic. The traffic patterns and protocol behaviour of new web protocols is very different. It is therefore important to assess the implications on the design and operation of satellite systems as the new web is increasingly used. This is the focus of this document. The document (TN3.1) reviews the current state-of-the-art of web technologies and surveys the recent proposals, such as SDPY. This document reviews the problems these protocols are trying to solve, and notes the way they try to solve them. In particular, the HTTP/2.0 standard is a new Internet application-layer that defines a new semantic. This is presently a joint effort between the World Wide Web Consortium (W3C) and the Internet Engineering Task Force (IETF). The starting point for the standard inherits ideas from SPDY, an open standard developed by Google and currently available in a wide range of web browsers, including Chromium, Mozilla Firefox and Opera. HTTP/2.0 promises to reduce web page load latency and improve web security using a combination of techniques, including compression, and multiplexing.Project(s): Satellite Communications Network of Excellence
Secchi R, Gotta A, Roseti C, Collina M, Fairhurst G, Sun Zautoreihiliaffiliazione Altro
The new paradigm of web usage has motivated in recent years a series of proposals to update the standard Internet protocols related to web traffic. Some of these proposals provided suggestions to upgrade or even completely replace current Hypertext Transport Protocol (HTTP). Others, instead, focused on new TCP transport mechanisms (larger initial window, fast connection open, congestion window validation, tail loss probe, etc.) that are meant to accelerate the completion time of short data transfers. Web technologies are penetrating areas of computer-science before only the prerogative of dedicated computer systems, such as Cloud computing and Service-oriented applications. Web technologies are becoming increasingly prevalent as the delivery model for a wide range of applications, using methods such as Service-oriented architecture (SOA) or software as a service (SaaS). These methods implement the concept of ASP (application service provider) and on-demand computing software delivery: the provider hosts commercially available software and delivers copies of it over the Web, customising the software according to a client's needs. These changes are driving significant alterations in the traffic patterns generated by applications, but the impact of such changes are still uncertain. These changes are also set to change the requirements placed on a network - with an increasing emphasis on minimising web page download time, and an increasing need to consider on-off interactivity. The motivation for transport changes is a growing availability of high speed xDSL/cable access. These high-speed services differ from most wireless and satellite systems in key ways. Current wireless/satellite systems typically employ dynamic capacity schemes with protocol accelerators and access methods that have been tuned for the existing web traffic. The traffic patterns and protocol behaviour of new web protocols is very different. It is therefore important to assess the implications on the design and operation of satellite systems as the new web is increasingly used. This is the focus of this document. The document (TN3.1) reviews the current state-of-the-art of web technologies and surveys the recent proposals, such as SDPY. This document reviews the problems these protocols are trying to solve, and notes the way they try to solve them. In particular, the HTTP/2.0 standard is a new Internet application-layer that defines a new semantic. This is presently a joint effort between the World Wide Web Consortium (W3C) and the Internet Engineering Task Force (IETF). The starting point for the standard inherits ideas from SPDY, an open standard developed by Google and currently available in a wide range of web browsers, including Chromium, Mozilla Firefox and Opera. HTTP/2.0 promises to reduce web page load latency and improve web security using a combination of techniques, including compression, and multiplexing.Project(s): Satellite Communications Network of Excellence
2013
Other
Restricted
SatNEx III - Analysis and characterisation of new web technology
Cruiskshank H, Secchi R, Gotta A, Roseti C, Collina M, Fairhurst G, Sun Z
his is the second report in a series of 3 reports. A previous report, TN.3.1, described the evolution of SPDY, the multiplexing architecture and interfaces. This report describes the experimental methods and results. A final report will draw conclusions from this work and provide recommendations for further study.Project(s): Satellite Communications Network of Excellence
Cruiskshank H, Secchi R, Gotta A, Roseti C, Collina M, Fairhurst G, Sun Z
his is the second report in a series of 3 reports. A previous report, TN.3.1, described the evolution of SPDY, the multiplexing architecture and interfaces. This report describes the experimental methods and results. A final report will draw conclusions from this work and provide recommendations for further study.Project(s): Satellite Communications Network of Excellence
2014
Other
Restricted
Performance evaluation of HTTP and SPDY over a DVB-RCS satellite link with different BoD schemes.
Caviglione L, Gotta A, Salam A A, Roseti C, Zampognaro F
The rapid evolution of the Web imposes the need of enhanc- ing the HTTP over satellite channels. To this aim, SPDY is a protocol engineered to reduce download times of content rich pages, as well as for managing links characterized by large Round Trip Times (RTTs) and high packet losses. With such features, it could be an efficient solu- tion to cope with performance degradations of HTTP over satellite. In this perspective, this paper compares the behaviors of HTTP and SPDY over a DVB-RCS satellite link. To conduct a thorough set of tests over a realistic scenario, we used the Satellite Network Emulation Platform (SNEP). In addition, we evaluated how different Bandwidth on Demand (BoD) methods impact over the retrieval of a page. Results clearly indi- cate that SPDY could be an effective solution to deliver Web contents over satellites in a more efficient manner.
Caviglione L, Gotta A, Salam A A, Roseti C, Zampognaro F
The rapid evolution of the Web imposes the need of enhanc- ing the HTTP over satellite channels. To this aim, SPDY is a protocol engineered to reduce download times of content rich pages, as well as for managing links characterized by large Round Trip Times (RTTs) and high packet losses. With such features, it could be an efficient solu- tion to cope with performance degradations of HTTP over satellite. In this perspective, this paper compares the behaviors of HTTP and SPDY over a DVB-RCS satellite link. To conduct a thorough set of tests over a realistic scenario, we used the Satellite Network Emulation Platform (SNEP). In addition, we evaluated how different Bandwidth on Demand (BoD) methods impact over the retrieval of a page. Results clearly indi- cate that SPDY could be an effective solution to deliver Web contents over satellites in a more efficient manner.
2014
Other
Restricted
Characterizing SPDY over high latency satellite channels
Caviglione L, Gotta A
The increasing complexity of Web contents and the growing diffusion of mobile terminals, which use wireless and satellite links to get access to the Internet, impose the adoption of more specialized protocols. In particular, we focus on SPDY, a novel protocol introduced by Google to optimize the retrieval of complex webpages, to manage large Round Trip Times and high packet losses channels. In this perspective, the paper characterizes SPDY over high latency satellite links, especially with the goal of understanding whether it could be an efficient solution to cope with performance degradations typically affecting Web 2.0 services. To this aim, we implemented an experimental set-up, composed of an ad-hoc proxy, a wireless link emulator, and an instrumented Web browser. The results clearly indicate that SPDY can enhance the performances in terms of loading times, and reduce the traffic fragmentation. Moreover, owing to its connection multiplexing architecture, SPDY can also mitigate the transport layer complexity, which is critical when in presence of Performance Enhancing Proxies usually deployed to isolate satellite trunks.
Caviglione L, Gotta A
The increasing complexity of Web contents and the growing diffusion of mobile terminals, which use wireless and satellite links to get access to the Internet, impose the adoption of more specialized protocols. In particular, we focus on SPDY, a novel protocol introduced by Google to optimize the retrieval of complex webpages, to manage large Round Trip Times and high packet losses channels. In this perspective, the paper characterizes SPDY over high latency satellite links, especially with the goal of understanding whether it could be an efficient solution to cope with performance degradations typically affecting Web 2.0 services. To this aim, we implemented an experimental set-up, composed of an ad-hoc proxy, a wireless link emulator, and an instrumented Web browser. The results clearly indicate that SPDY can enhance the performances in terms of loading times, and reduce the traffic fragmentation. Moreover, owing to its connection multiplexing architecture, SPDY can also mitigate the transport layer complexity, which is critical when in presence of Performance Enhancing Proxies usually deployed to isolate satellite trunks.
2014
Other
Restricted
Does SPDY improve the Web 2.0 experience on satellite links?
Cardaci A, Caviglione L, Gotta A
During the last years, the Web has grown in terms og complexity, while the evolution of the HTTP has not experienced the same trand. Even if HTTP 1.1 adds improvements like persistent connections and pipelining, they are not decisive, especially today. In parallel, satellites play a key role for accessing the Internet everywhere, yet suffering of his latencies and packet losses, which degrade the browsing experience. Consequently, the investigation of protocols removing the limitations of HTTP, alsso in challenging scenarios, is crucial both for the Industry and the Academia. In this perspective, this paper introduces SPDY, and showcases its performance evaluation over real and emulated satellite links.
Cardaci A, Caviglione L, Gotta A
During the last years, the Web has grown in terms og complexity, while the evolution of the HTTP has not experienced the same trand. Even if HTTP 1.1 adds improvements like persistent connections and pipelining, they are not decisive, especially today. In parallel, satellites play a key role for accessing the Internet everywhere, yet suffering of his latencies and packet losses, which degrade the browsing experience. Consequently, the investigation of protocols removing the limitations of HTTP, alsso in challenging scenarios, is crucial both for the Industry and the Academia. In this perspective, this paper introduces SPDY, and showcases its performance evaluation over real and emulated satellite links.
2014
Other
Restricted
SatNEx III - Future Web technologies and protocols over broadband GEO satellite networks
Gotta A, Fairthurst G, Secchi R, Vanelli Coralli A, Collina M, Luglio M, Roseti C, Sun Z, Cruickshank H, Caviglione L
This project explores the potential implications of introducing the HTTP/2.0 web technology on the design and operation of satellite networks. It has been recognised that as network bandwidth increases, the greater obstacle to the performance of web technology is latency rather than scarcity of capacity. HTTP/2.0 [RD-8] is a new protocol being design by the Internet Engineering Task Force (IETF) and World Wide Web Consortium (W3C) to address the limitations and lack of flexibility of the currently widely deployed HTTP/1.1 [RD-4]. The origin of the emerging HTTP/2.0 standard may be traced back to a GoogleTM suite of protocols, called SPDY. Proposed modifications to HTTP/1.1 include suppression of unnecessary Round Trip Time (RTT) delays to request and deliver web objects, multiplexing of web streams into a single connection, removal of the head of line (HoL) blocking, more compact encoding of HTTP headers, server initiated transmissions (Server Push), a new security model, and an extensible design. In parallel, a number of initiatives from well-known IT actors (GoogleTM, AppleTM etc) have proposed new transport methods, such as QUIC [RD-7] or Minion [RD-23], to enhance performance for web traffic. It is expected that the final HTTP/2.0 specification will replace HTTP/1.1 in every scenario HTTP/1.1 is currently used. The goal of Task3 of CoO3 Satnex-III was to understand the trajectory of the emerging web technologies and to evaluate the expected impact on satellite networking. Different aspects have been analysed by Satnex partners using both real satellite testbeds and emulation. This analysis included evaluation of SPDY performance over satellite and experiments to understand the expected interaction with PEPs (including scenarios with a SPDY proxy at a satellite gateway), the impact of security, and the effect of satellite capacity allocation mechanisms. The analysis also considered the impact of application protocols and the delay induced by end- system networks, such as a satellite-connected WiFi network. In general, experimental results show that HTTP/2.0 benefits the performance of web browsing via satellite by reducing latency and significantly lowering the overhead for several types of web pages. In particular, multiplexing a sequence of small web objects on a webpage onto a single connection enables siginicant gain and effectively reduces the HTTP overhead per object and per connection. The Server Push feature of HTTP/2.0, adds the ability for the server to send objects without explicit request, and was found particularly useful to reduce the download time. However these gains come at a cost, since they impact the design and operation of satellite networks. We also observed places where the tested implementations did not perform optimally, and were performance over satellite-connected WiFi networks was less than would be expected with HTTP/1.1. However, at the time of writing, the work on HTTP/2.0 is not complete and many mechanisms remain to be finalised. Modifications and adjustments are expected in future. Moreover, the current software support for HTTP/2.0 is not yet completely stable, and is expected to continue to evolve long after initial deployment. Satellite networking equipment will need to be updated to support HTTP/2.0. In particular, designs must re-consider the integration of PEPs withHTTP/2.0 and the updated security model, based on Transport Layer Security (TLS). TLS encryption prevents visibility of HTTP headers at satellite equipment, preventing use of current 23089/10/NL/CLP Executive and Summary Report 15/40 III CoO3 - Task 3 - Future Web Technologies and Protocols over Broadband GEO Satellite Networks HTTP acceleration PEPs. Our tests suggest that this problem may be mitigated by HTTP/2.0 itself, because some of the functions implemented in application-layer PEPs (compression, pipeling/multiplexing, push) are already present in HTTP/2.0. HTTP/2.0 is still in a development phase and it is important for the satellite community to watch carefully its progress and understand the implications this will place on the design of the higher layer packet processing. This is especially important because the new model does not introduce a single solution, but more represents a toolkit of techniques that will continue to evolve and will be deployed incrementally over a timescale of months and years ahead. There is also a need to understand the implications on network design/configuration, to ensure that satellite continues to offer high quality service comparable to terrestrial networks, and a need to re-consider the role of PEP in this new architecture. We also urge the satellite networking community to influence development of these standards. As network latency becomes important there is increased focus on low- delay networks, and it is important to ensure that design decisions (maybe unintentional) do not prejudice the performance over long delay paths when the new protocols are deployed.
Gotta A, Fairthurst G, Secchi R, Vanelli Coralli A, Collina M, Luglio M, Roseti C, Sun Z, Cruickshank H, Caviglione L
This project explores the potential implications of introducing the HTTP/2.0 web technology on the design and operation of satellite networks. It has been recognised that as network bandwidth increases, the greater obstacle to the performance of web technology is latency rather than scarcity of capacity. HTTP/2.0 [RD-8] is a new protocol being design by the Internet Engineering Task Force (IETF) and World Wide Web Consortium (W3C) to address the limitations and lack of flexibility of the currently widely deployed HTTP/1.1 [RD-4]. The origin of the emerging HTTP/2.0 standard may be traced back to a GoogleTM suite of protocols, called SPDY. Proposed modifications to HTTP/1.1 include suppression of unnecessary Round Trip Time (RTT) delays to request and deliver web objects, multiplexing of web streams into a single connection, removal of the head of line (HoL) blocking, more compact encoding of HTTP headers, server initiated transmissions (Server Push), a new security model, and an extensible design. In parallel, a number of initiatives from well-known IT actors (GoogleTM, AppleTM etc) have proposed new transport methods, such as QUIC [RD-7] or Minion [RD-23], to enhance performance for web traffic. It is expected that the final HTTP/2.0 specification will replace HTTP/1.1 in every scenario HTTP/1.1 is currently used. The goal of Task3 of CoO3 Satnex-III was to understand the trajectory of the emerging web technologies and to evaluate the expected impact on satellite networking. Different aspects have been analysed by Satnex partners using both real satellite testbeds and emulation. This analysis included evaluation of SPDY performance over satellite and experiments to understand the expected interaction with PEPs (including scenarios with a SPDY proxy at a satellite gateway), the impact of security, and the effect of satellite capacity allocation mechanisms. The analysis also considered the impact of application protocols and the delay induced by end- system networks, such as a satellite-connected WiFi network. In general, experimental results show that HTTP/2.0 benefits the performance of web browsing via satellite by reducing latency and significantly lowering the overhead for several types of web pages. In particular, multiplexing a sequence of small web objects on a webpage onto a single connection enables siginicant gain and effectively reduces the HTTP overhead per object and per connection. The Server Push feature of HTTP/2.0, adds the ability for the server to send objects without explicit request, and was found particularly useful to reduce the download time. However these gains come at a cost, since they impact the design and operation of satellite networks. We also observed places where the tested implementations did not perform optimally, and were performance over satellite-connected WiFi networks was less than would be expected with HTTP/1.1. However, at the time of writing, the work on HTTP/2.0 is not complete and many mechanisms remain to be finalised. Modifications and adjustments are expected in future. Moreover, the current software support for HTTP/2.0 is not yet completely stable, and is expected to continue to evolve long after initial deployment. Satellite networking equipment will need to be updated to support HTTP/2.0. In particular, designs must re-consider the integration of PEPs withHTTP/2.0 and the updated security model, based on Transport Layer Security (TLS). TLS encryption prevents visibility of HTTP headers at satellite equipment, preventing use of current 23089/10/NL/CLP Executive and Summary Report 15/40 III CoO3 - Task 3 - Future Web Technologies and Protocols over Broadband GEO Satellite Networks HTTP acceleration PEPs. Our tests suggest that this problem may be mitigated by HTTP/2.0 itself, because some of the functions implemented in application-layer PEPs (compression, pipeling/multiplexing, push) are already present in HTTP/2.0. HTTP/2.0 is still in a development phase and it is important for the satellite community to watch carefully its progress and understand the implications this will place on the design of the higher layer packet processing. This is especially important because the new model does not introduce a single solution, but more represents a toolkit of techniques that will continue to evolve and will be deployed incrementally over a timescale of months and years ahead. There is also a need to understand the implications on network design/configuration, to ensure that satellite continues to offer high quality service comparable to terrestrial networks, and a need to re-consider the role of PEP in this new architecture. We also urge the satellite networking community to influence development of these standards. As network latency becomes important there is increased focus on low- delay networks, and it is important to ensure that design decisions (maybe unintentional) do not prejudice the performance over long delay paths when the new protocols are deployed.
2014
Other
Metadata Only Access
SatNex III - State-of-the-art Web Technologies and Protocols State-of-the-art Web Technologies and Protocols
Gotta A, Fairthurst G, Secchi R, Vanelli Coralli A, Collina M, Luglio M, Roseti C, Sun Z, Cruickshank H, Caviglione L
The new paradigm of web usage has motivated in recent years a series of proposals to update the standard Internet protocols related to web traffic. Some of these proposals provided suggestions to upgrade or even completely replace current Hypertext Transport Protocol (HTTP). Others, instead, focused on new TCP transport mechanisms (larger initial window, fast connection open, congestion window validation, tail loss probe, etc.) that are meant to accelerate the completion time of short data transfers. Web technologies are penetrating areas of computer-science before only the prerogative of dedicated computer systems, such as Cloud computing and Service- oriented applications. Web technologies are becoming increasingly prevalent as the delivery model for a wide range of applications, using methods such as Service- oriented architecture (SOA) or software as a service (SaaS). These methods implement the concept of ASP (application service provider) and on-demand computing software delivery: the provider hosts commercially available software and delivers copies of it over the Web, customising the software according to a client's needs. These changes are driving significant alterations in the traffic patterns generated by applications, but the impact of such changes are still uncertain. These changes are also set to change the requirements placed on a network - with an increasing emphasis on minimising web page download time, and an increasing need to consider on-off interactivity. The motivation for transport changes is a growing availability of high speed xDSL/cable access. These high-speed services differ from most wireless and satellite systems in key ways. Current wireless/satellite systems typically employ dynamic capacity schemes with protocol accelerators and access methods that have been tuned for the existing web traffic. The traffic patterns and protocol behaviour of new web protocols is very different. It is therefore important to assess the implications on the design and operation of satellite systems as the new web is increasingly used. This is the focus of this document. The document (TN3.1) reviews the current state-of-the-art of web technologies and surveys the recent proposals, such as SDPY. This document reviews the problems these protocols are trying to solve, and notes the way they try to solve them. In particular, the HTTP/2.0 standard is a new Internet application-layer that defines a new semantic. This is presently a joint effort between the World Wide Web Consortium (W3C) and the Internet Engineering Task Force (IETF). The starting point for the standard inherits ideas from SPDY, an open standard developed by Google and currently available in a wide range of web browsers, including Chromium, Mozilla Firefox and Opera. HTTP/2.0 promises to reduce web page load latency and improve web security using a combination of techniques, including compression, and multiplexing.
Gotta A, Fairthurst G, Secchi R, Vanelli Coralli A, Collina M, Luglio M, Roseti C, Sun Z, Cruickshank H, Caviglione L
The new paradigm of web usage has motivated in recent years a series of proposals to update the standard Internet protocols related to web traffic. Some of these proposals provided suggestions to upgrade or even completely replace current Hypertext Transport Protocol (HTTP). Others, instead, focused on new TCP transport mechanisms (larger initial window, fast connection open, congestion window validation, tail loss probe, etc.) that are meant to accelerate the completion time of short data transfers. Web technologies are penetrating areas of computer-science before only the prerogative of dedicated computer systems, such as Cloud computing and Service- oriented applications. Web technologies are becoming increasingly prevalent as the delivery model for a wide range of applications, using methods such as Service- oriented architecture (SOA) or software as a service (SaaS). These methods implement the concept of ASP (application service provider) and on-demand computing software delivery: the provider hosts commercially available software and delivers copies of it over the Web, customising the software according to a client's needs. These changes are driving significant alterations in the traffic patterns generated by applications, but the impact of such changes are still uncertain. These changes are also set to change the requirements placed on a network - with an increasing emphasis on minimising web page download time, and an increasing need to consider on-off interactivity. The motivation for transport changes is a growing availability of high speed xDSL/cable access. These high-speed services differ from most wireless and satellite systems in key ways. Current wireless/satellite systems typically employ dynamic capacity schemes with protocol accelerators and access methods that have been tuned for the existing web traffic. The traffic patterns and protocol behaviour of new web protocols is very different. It is therefore important to assess the implications on the design and operation of satellite systems as the new web is increasingly used. This is the focus of this document. The document (TN3.1) reviews the current state-of-the-art of web technologies and surveys the recent proposals, such as SDPY. This document reviews the problems these protocols are trying to solve, and notes the way they try to solve them. In particular, the HTTP/2.0 standard is a new Internet application-layer that defines a new semantic. This is presently a joint effort between the World Wide Web Consortium (W3C) and the Internet Engineering Task Force (IETF). The starting point for the standard inherits ideas from SPDY, an open standard developed by Google and currently available in a wide range of web browsers, including Chromium, Mozilla Firefox and Opera. HTTP/2.0 promises to reduce web page load latency and improve web security using a combination of techniques, including compression, and multiplexing.
See at:
CNR IRIS
2014
Journal article
Open Access
Characterizing SPDY over high latency satellite channels
Caviglione L, Gotta A
The increasing complexity of Web contents and the growing diffusion of mobile terminals, which use wireless and satellite links to get access to the Internet, impose the adoption of more specialized protocols. In particular, we focus on SPDY, a novel protocol introduced by Google to optimize the retrieval of complex webpages, to manage large Round Trip Times and high packet losses channels. In this perspective, the paper characterizes SPDY over high latency satellite links, especially with the goal of understanding whether it could be an efficient solution to cope with performance degradations typically affecting Web 2.0 services. To this aim, we implemented an experimental set-up, composed of an ad-hoc proxy, a wireless link emulator, and an instrumented Web browser. The results clearly indicate that SPDY can enhance the performances in terms of loading times, and reduce the traffic fragmentation. Moreover, owing to its connection multiplexing architecture, SPDY can also mitigate the transport layer complexity, which is critical when in presence of Performance Enhancing Proxies usually deployed to isolate satellite trunks.Source: ICST TRANSACTIONS ON MOBILE COMMUNICATIONS AND APPLICATIONS, vol. 14 (issue 5), pp. e3-10
Caviglione L, Gotta A
The increasing complexity of Web contents and the growing diffusion of mobile terminals, which use wireless and satellite links to get access to the Internet, impose the adoption of more specialized protocols. In particular, we focus on SPDY, a novel protocol introduced by Google to optimize the retrieval of complex webpages, to manage large Round Trip Times and high packet losses channels. In this perspective, the paper characterizes SPDY over high latency satellite links, especially with the goal of understanding whether it could be an efficient solution to cope with performance degradations typically affecting Web 2.0 services. To this aim, we implemented an experimental set-up, composed of an ad-hoc proxy, a wireless link emulator, and an instrumented Web browser. The results clearly indicate that SPDY can enhance the performances in terms of loading times, and reduce the traffic fragmentation. Moreover, owing to its connection multiplexing architecture, SPDY can also mitigate the transport layer complexity, which is critical when in presence of Performance Enhancing Proxies usually deployed to isolate satellite trunks.Source: ICST TRANSACTIONS ON MOBILE COMMUNICATIONS AND APPLICATIONS, vol. 14 (issue 5), pp. e3-10
2014
Conference article
Restricted
Performance evaluation of HTTP and SPDY over a DVB-RCS satellite link with different BoD schemes
Caviglione L, Gotta A, Salam A A, Roseti C, Zampognaro F
The rapid evolution of the Web imposes the need of enhanc- ing the HTTP over satellite channels. To this aim, SPDY is a protocol engineered to reduce download times of content rich pages, as well as for managing links characterized by large Round Trip Times (RTTs) and high packet losses. With such features, it could be an efficient solu- tion to cope with performance degradations of HTTP over satellite. In this perspective, this paper compares the behaviors of HTTP and SPDY over a DVB-RCS satellite link. To conduct a thorough set of tests over a realistic scenario, we used the Satellite Network Emulation Platform (SNEP). In addition, we evaluated how different Bandwidth on Demand (BoD) methods impact over the retrieval of a page. Results clearly indi- cate that SPDY could be an effective solution to deliver Web contents over satellites in a more efficient manner.
Caviglione L, Gotta A, Salam A A, Roseti C, Zampognaro F
The rapid evolution of the Web imposes the need of enhanc- ing the HTTP over satellite channels. To this aim, SPDY is a protocol engineered to reduce download times of content rich pages, as well as for managing links characterized by large Round Trip Times (RTTs) and high packet losses. With such features, it could be an efficient solu- tion to cope with performance degradations of HTTP over satellite. In this perspective, this paper compares the behaviors of HTTP and SPDY over a DVB-RCS satellite link. To conduct a thorough set of tests over a realistic scenario, we used the Satellite Network Emulation Platform (SNEP). In addition, we evaluated how different Bandwidth on Demand (BoD) methods impact over the retrieval of a page. Results clearly indi- cate that SPDY could be an effective solution to deliver Web contents over satellites in a more efficient manner.
2014
Journal article
Restricted
A TCP/IP satellite infrastructure for sensing operations in emergency contexts
Gotta A, Luglio M, Roseti C
The deployment of sensor networks for emergency management must be considered as an irreplaceable support for both monitoring and rescue activities. Depending on the scenario the use of satellite links as a segment of the network ensures connectivity where no other network is available and in some case can also provide an efficient and cost effective means to transfer data. This work aims to define architecture, to identify of optimum solution and to evaluate performance, in terms of throughput and service delay, when a protocol stack - from layer II to layer IV - is considered over a DVB-RCS system. The considered platform is composed of clusters of sensors (including low data rate devices and bulk data cameras) deployed over vast geographical areas, which collect on ground and distribute via satellite multimedia information, i.e. audio, video and sensed data, either for emergency or monitoring operations. A geostationary system was selected in order to guarantee high flexibility in terms of channel capacity. The proposed architecture assumes a session layer protocol, between the transport and application layers, which manages the multiplexing of streams coming from the input sources. The proposed architecture integrates wireless sensor networks and satellite networks, implying to approach technological issues from access layer up to transport and session layers, with heterogeneous traffic sources multiplexed by a satellite gateway, before being encapsulated into TCP/IP flows. Simulation results show the validity of the proposed architecture and protocol solutions.Source: COMPUTER NETWORKS (1999), vol. 60, pp. 147-159
Gotta A, Luglio M, Roseti C
The deployment of sensor networks for emergency management must be considered as an irreplaceable support for both monitoring and rescue activities. Depending on the scenario the use of satellite links as a segment of the network ensures connectivity where no other network is available and in some case can also provide an efficient and cost effective means to transfer data. This work aims to define architecture, to identify of optimum solution and to evaluate performance, in terms of throughput and service delay, when a protocol stack - from layer II to layer IV - is considered over a DVB-RCS system. The considered platform is composed of clusters of sensors (including low data rate devices and bulk data cameras) deployed over vast geographical areas, which collect on ground and distribute via satellite multimedia information, i.e. audio, video and sensed data, either for emergency or monitoring operations. A geostationary system was selected in order to guarantee high flexibility in terms of channel capacity. The proposed architecture assumes a session layer protocol, between the transport and application layers, which manages the multiplexing of streams coming from the input sources. The proposed architecture integrates wireless sensor networks and satellite networks, implying to approach technological issues from access layer up to transport and session layers, with heterogeneous traffic sources multiplexed by a satellite gateway, before being encapsulated into TCP/IP flows. Simulation results show the validity of the proposed architecture and protocol solutions.Source: COMPUTER NETWORKS (1999), vol. 60, pp. 147-159
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2016
Contribution to book
Restricted
Performance evaluation of HTTP and SPDY over a DVB-RCS satellite link with different BoD schemes
Caviglione L, Gotta A, Abdel Salam A, Luglio M, Roseti C, Zampognaro F
The rapid evolution of the Web imposes the need of enhancing the HTTP over satellite channels. To this aim, SPDY is a protocol engineered to reduce download times of content rich pages, as well as for managing links characterized by large Round Trip Times (RTTs) and high packet losses. With such features, it could be an efficient solution to cope with performance degradations of HTTP over satellite. In this perspective, this paper compares the behaviors of HTTP and SPDY over a DVB-RCS satellite link. To conduct a thorough set of tests over a realistic scenario, we used the Satellite Network Emulation Platform (SNEP). In addition, we evaluated how different Bandwidth on Demand (BoD) methods impact over the retrieval of a page. Results clearly indicate that SPDY could be an effective solution to deliver Web contents over satellites in a more efficient manner.Source: LECTURE NOTES OF THE INSTITUTE FOR COMPUTER SCIENCES, SOCIAL INFORMATICS AND TELECOMMUNICATIONS ENGINEERING (INTERNET), pp. 34-44
Caviglione L, Gotta A, Abdel Salam A, Luglio M, Roseti C, Zampognaro F
The rapid evolution of the Web imposes the need of enhancing the HTTP over satellite channels. To this aim, SPDY is a protocol engineered to reduce download times of content rich pages, as well as for managing links characterized by large Round Trip Times (RTTs) and high packet losses. With such features, it could be an efficient solution to cope with performance degradations of HTTP over satellite. In this perspective, this paper compares the behaviors of HTTP and SPDY over a DVB-RCS satellite link. To conduct a thorough set of tests over a realistic scenario, we used the Satellite Network Emulation Platform (SNEP). In addition, we evaluated how different Bandwidth on Demand (BoD) methods impact over the retrieval of a page. Results clearly indicate that SPDY could be an effective solution to deliver Web contents over satellites in a more efficient manner.Source: LECTURE NOTES OF THE INSTITUTE FOR COMPUTER SCIENCES, SOCIAL INFORMATICS AND TELECOMMUNICATIONS ENGINEERING (INTERNET), pp. 34-44
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CNR IRIS | CNR IRIS | link.springer.com