Search results for "Differentiated service"
showing 10 items of 15 documents
The Perceived Role of Technology in Career Guidance among Practitioners Who are Experienced Internet Users
2011
The increasing use of technology is placing new demands on career guidance practitioners. This article examines what changes, if any, have occurred in the perceptions of guidance practitioners regarding their role and the role of the internet in meeting guidance goals and delivering career guidance services. The data were collected in focus groups in 2001–2002 and a follow-up study in 2010. A total of seven focus groups were held. The data were analysed using combined methods. The results indicated that practitioners now observe that the need for differentiated service delivery modes is more explicit due to varied levels of readiness in decision-making and ICT literacy.
PCP: An End-to end Measurement Based Call Admission Control for Real-Time Services Over IP Networks
2000
Distributed end-to-end measurement based connection admission control mechanisms have been recently proposed. The goal of these schemes is to provide tight QoScon trol on a per connection basis by means of measurements taken by the edge nodes and priority based forwarding procedure at internal nodes. Since the additional flows handling procedures are implemented at the border routers and the forwarding mechanisms are for flows aggregates only, the approach is fully scalable and compatible with the IETF Differentiated Service proposal. The aim of this paper is to propose specific schemes and to investigate the advantages and limits of the approach by analyzing the basic mechanisms and evalua…
Adding Real-Time Networking and QoS Capabilities to RTLinux-GPL
2006
This paper presents an architecture to build distributed embedded real-time systems in the RTLinux-GPL platform. The architecture (built in a layered fashion) has being built around open source projects ranging from Ethernet drivers to a CORBA environment. The paper focuses on those layers that give support for QoS and real-time networking over Ethernet networks. The main ideas are: to accomplish deterministic access times by using a TDMA protocol over Ethernet and to multiplex different types of traffic in that real-time network, providing different service types (QoS) to each type of traffic without jeopardizing the a priori guarantee of the system's real-time properties. Traffic types in…
An API for Advanced Traffic Control in Diffserv Routers
2003
Distributed per-flow admission control is a promising solution for Differentiated Services networks. Its deployment in DiffSery domains requires the ability to suitably configure, in each network router, low-level packet forwarding mechanisms, such as packet dropping algorithms driven by traffic measurements. In this paper we first show that performance effectiveness is achieved by means of non traditional configuration of the forwarding mechanisms. Hence, we propose a modular Application Program Interface that allows to flexibly and adaptively configure the forwarding/dropping behavior associated to a router’s output queue, well beyond the traditional RED/RIO active queue management scheme…
Semantic Web Services for Smart Devices in a “Global Understanding Environment”
2003
Various Web resources and services are usually assumed to be used and accessed by human users (current Web) or by software agents on behalf of human users (emerging Semantic Web). However industry emerges also a new group of “users”, which are smart industrial devices, robots or any other objects, which can be adapted to the (Semantic) Web environment. They would need special services for e.g. online condition monitoring, information provisioning, remote diagnostics, maintenance support, etc. The goal of this paper is to specify main requirements to Web services that automatically follow up and predict the performance and maintenance needs of field devices. Semantic Web enabled services for…
Semantic Web Services for Smart Devices Based on Mobile Agents
2005
Among traditional users of Web resources, industry has a growing set of smart industrial devices with embedded intelligence. Just like humans, they need online services (i.e., for condition monitoring, remote diagnostics, maintenance, etc.). In this paper, we present one possible implementation framework for such Web services. Such services should be Semantic Web enabled and form a Service Network based on internal and external agents’ platforms, which can host heterogeneous mobile agents and coordinate them to perform needed tasks. The concept of a “mobile service component†assumes not only exchanging queries and service responses, but also delivering and composition of a service pro…
An analytical model of a new packet marking algorithm for TCP flows: Preliminary insights
2004
In differentiated services networks, packet marking schemes can be devised to differentiate packets belonging to a same TCP flow, with the goal of improving the experienced performance. This paper presents an analytical model for an adaptive packet marking scheme proposed in our previous work. The model combines three specific sub-models aimed at describing i) the TCP sources aggregate ii) the marker, and iii) the network status. Some preliminary simulative results seem to validate the model.
Per-flow signalling extension across DiffServ domains
2003
This paper describes a framework devised to extend per-flow admission control operation across Differentiated Services domains. Although the specific case of interoperability with RSVP is under discussion, our proposal can be easily adapted to other hop-by-hop signalling protocols. In our framework, DiffSery border routers accomplish three tasks. First, during the set-up phase, flows are mapped onto PHB groups on the basis of their QoS and traffic specifications. Second, signalling packets are tunnelled into IP packets marked as “probes”, where the “probe” marking is a DCSP value associated to the considered PHB Group. Third, when the flow set-up is complete, flow data packets are marked as…
Fuzzy-neural Web switch supporting differentiated service
2006
New designs of the Web switches must incorporate a client-and-server-aware adaptive dispatching algorithm to be able to optimize multiple static and dynamic services providing quality of service and service differentiation. This paper presents such an algorithm called FNRD (Fuzzy-Neural Request Distribution) which operates at layer-7 of the OSI protocol stack. This algorithm assigns each incoming request to the server with the least expected response time estimated using the fuzzy approach. FNRD has ability for learning and adaptation by means of a neural network feedback loop. We demonstrate through the simulations that our dispatching policy is more effective than state-of-the-art layer-7…
Performance Evaluation of a new Adaptive Packet Marking Scheme for TCP over DiffServ Networks
2004
In differentiated services (DiffServ) networks, packets may receive a different treatment according to their differentiated services code point (DSCP) label. As a consequence, packet marking schemes can be devised to differentiate packets belonging to the same TCP flow, with the goal of improving the experienced performance. The paper presents an extensive performance evaluation of a new adaptive packet marking scheme, applied to a traffic scenario composed of TCP flows with different lengths. The proposed marking scheme is most efficient when applied to a scenario composed of all long-lived flows. In a realistic mixed traffic scenario, composed of both long-lived and short-lived TCP flows,…