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We propose a network scheme with Admission Control AC for TCP flows, which can provide different minimum throughputs and isolation between flows. It is built with simple mechanisms without per-flow state, per flow signaling or per-flow processing in the core. The whole scheme uses a small set of packet classes, with a different discarding priority assigned to each one. The AC is implicit, edge-to-edge and based on per-aggregate throughput measurements. The out packets of the aggregation of accepted flows i.e., the packets that correspond to the flows' extra throughput act as a probing flow to test if the throughput in the network path is enough to satisfy the flow's request. Then signaling packets carry the per-aggregate throughput measurement from the egress to the ingress, where the AC decision is made. Through simulation we show that the scheme guarantees the requested minimum throughput to accepted flows and achieves a good utilization of resources.

TCP flows generated by applications such as the Web or FTP require a minimum network throughput and can also benefit from an extra throughput due to their rate-adaptive algorithms. To build a guaranteed minimum throughput service, the authors propose a scheme with Admission Control (AC) using a small set of packet classes in a core-stateless network. At the ingress of the network, each flow packet is marked as one of the set of classes, and within the network, each class is assigned a different discarding priority. The AC method is based on edge-to-edge per flow measurements and requires flows to be sent at a minimum rate. The scheme is able to provide different minimum throughput to different users and protection against nonresponsive sources. The authors evaluate the scheme through simulation using different traffic loads consisting of TCP flows that carry files of varying sizes. In the simulation, TCP uses a new algorithm that forces the source to keep the short-term sending rate above a desired minimum rate. The authors study the influence of several parameters on the performance of the scheme in different network topologies. The results show that the scheme guarantees the requested throughput to accepted flows and achieves a high utilization of network resources, similar to the ideal results of a classical hop-by-hop AC.

We propose a new scheme for a network service that guarantees a minimum throughput to flows accepted by admission control (AC). The whole scheme only uses a small set of packet classes in a core-stateless network. At the ingress of the network each flow packet is marked into one of the sets of classes, and within the network, each class is assigned a different discarding priority. The AC method is based on edge-to-edge per-flow throughput measurements using the first packets of the flow, and it requires flows to send with a minimum rate. We evaluate the scheme through simulations in a simple bottleneck topology with different traffic loads consisting of TCP flows that carry files of varying sizes. We use a modified TCP source with a new algorithm that forces the source to send with a minimum rate. We compare our scheme with the best-effort service and we study the influence of the measurement duration on the scheme's performance. The results prove that the scheme guarantees the requested throughput to accepted flows and achieves a high utilization of network resources. Copyright © 2006 John Wiley & Sons, Ltd.

In this paper, a network laboratory for distance learning of basic concepts in IP networking is presented. Through a web interface, students can choose various configurations of a real private network (number of routers and subnetworks, use of IPv4/IPv6, etc.), and learn about them using Linux network commands. The utilization of the virtual laboratory and how it is implemented are described.

Admission Control (AC) is an efficient way of dealing with congestion situations in a network. Using AC, when network resources in a path are not enough for all flows (i.e., during congestion), some of the flows receive the requested service and the rest do not. Congestion situations can be reduced by increasing network resources or by optimizing their use through better routing techniques, but if congestion still occurs, AC achieves efficient use of network resources by maximizing the number of satisfied flows. However, using AC complicates the network scheme, and therefore a major concern is making the AC as simple as possible. In this paper we review the main AC schemes that have been proposed for the Internet, focusing on the simplicity of their architectures in terms of the number of nodes that participate in the AC, the required state, the use of signaling, and others.

Following the iterative research cycle process, this chapter elaborates a methodology and documents the steps followed for the design of a dynamic multicast routing algorithm, referred to as Greedy Compact Multicast Routing. Starting from the design of the dynamic multicast routing algorithm, we then evaluate by simulation on large-scale topologies its performance and compare them with the Abraham compact multicast routing scheme and two other reference schemes, namely the Shortest Path Tree (SPT) and the Steiner Tree (ST) algorithm. Performance evaluation and comparison include i) the stretch of the multicast routing paths also referred to as multicast distribution tree (MDT), ii) the memory space required to store the resulting routing table entries, and iii) the total communication or messaging cost, i.e., the number of messages exchanged to build the MDT. However, such performance evaluation is a necessary but not a sufficient condition to meet in order to expect deployment of multicast routing. Indeed, if one can determine that traffic exchanges are spatially and temporally concentrated, this would provide elements indicating the relevance for the introduction of such scheme in the Internet. Otherwise (if traffic exchanges are spatially and temporally diverse, i.e., highly distributed), then very few of them would benefit from a (shared) point-to-multipoint routing paths and multicast routing scheme would be less useful. For this purpose, we have conducted a multicast tree inference study. In turn, data and results obtained from these studies provides more realistic scenarios for emulation experiments against the currently deployed approach combining MBGP and PIMdeployed in IPTV or mVPN context.

In this paper a novel methodology aimed at minimizing the probability of network failure and the failure impact (in terms of QoS degradation) while optimizing the resource consumption is introduced. A detailed study of MPLS recovery techniques and their GMPLS extensions are also presented. In this scenario, some features for reducing the failure impact and offering minimum failure probabilities at the same time are also analyzed. Novel two-step routing algorithms using this methodology are proposed. Results show that these methods offer high protection levels with optimal resource consumption.

TCP flows from applications such as the web or ftp are well supported by a Guaranteed Minimum Throughput Service (GMTS), which provides a minimum network throughput to the flow and, if possible, an extra throughput. We propose a scheme for a GMTS using Admission Control (AC) that is able to provide different minimum throughput to different users and that is suitable for "standard" TCP flows. Moreover, we consider a multidomain scenario where the scheme is used in one of the domains, and we propose some mechanisms for the interconnection with neighbor domains. The whole scheme uses a small set of packet classes in a core-stateless network where each class has a different discarding priority in queues assigned to it. The AC method involves only edge nodes and uses a special probing packet flow (marked as the highest discarding priority class) that is sent continuously from ingress to egress through a path. The available throughput in the path is obtained at the egress using measurements of flow aggregates, and then it is sent back to the ingress. At the ingress each flow is detected using an implicit way and then it is admission controlled. If it is accepted, it receives the GMTS and its packets are marked as the lowest discarding priority classes; otherwise, it receives a best-effort service. The scheme is evaluated through simulation in a simple "bottleneck" topology using different traffic loads consisting of "standard" TCP flows that carry files of varying sizes.

TCP flows generated by applications such as the web or ftp require a minimum network throughput to satisfy users. To build this service, we propose a scheme with Admission Control (AC) using a small set of packet classes in a core-stateless network. At the ingress each flow packet is marked as one of the set of classes, and within the network, each class is assigned a different discarding priority. The AC method is based on edge-to-edge per-flow measurements, and it requires flows to be sent at a minimum rate. The scheme is able to provide different throughput to different flows and protection against non-responsive sources. We evaluate the scheme through simulation in several network topologies with different traffic loads consisting of TCP flows that carry files of varying sizes. In the simulation, TCP uses a new algorithm to keep the short-term sending rate above a minimum value. The results prove that the scheme guarantees the throughput to accepted flows and achieves high utilization of resources, similar to the ideal results of a classical hop-by-hop AC.

Quality of Service (QoS) guarantees must be supported in a network that intends to carry real-time and multimedia traffic effectively. The effort of satisfying the QoS different requirements of these applications has resulted in the proposals of several QoS-based frameworks, such as Integrated Services (IntServ) [1], Differentiated Services (DiffServ) [2], and Multi-Protocol Label Switching (MPLS) [6].

We present a system for dynamic network resource configuration in environments with bandwidth reservation. The proposed system is completely distributed and automates the mechanisms for adapting the logical network to the offered load. The system is able to manage dynamically a logical network such as a virtual path network in ATM or a label switched path network in MPLS or GMPLS. The system design and implementation is based on a multi-agent system (MAS) which make the decisions of when and how to change a logical path. Despite the lack of a centralised global network view, results show that MAS manages the network resources effectively, reducing the connection blocking probability and, therefore, achieving better utilisation of network resources. We also include details of its architecture and implementation.

TCP elastic traffic is generated by the traditional “data” applications in the Internet, such as web browsing, peer-to-peer file sharing, ftp, e-mail and other. These applications are built on top of TCP, which provides reliable transfers and adjusts the sending rate to the network conditions to achieve the maximum possible throughput, a feature that makes TCP flows to be called “elastic”. From the point of view of the network, TCP elastic traffic requires the maximum possible throughput above a minimum value, a network service that we call the Minimum Throughput Service (MTS). In this paper we survey the main network schemes that have been proposed in the Internet to provide this service for TCP elastic traffic, classified in two broad groups, the ones that do not use Admission Control (AC) and the ones that do use it. For each network scheme we describe the main characteristics of the service (whether the minimum throughput can be different or is the same for all flows, whether isolation among flows is provided, etc.) and their architecture (the specific traffic conditioning, queue disciplines and AC mechanisms used, the required state, the use of signaling, etc.).

Due to the high cost of a large ATM network working up to full strength to apply our ideas about network management, i.e., dynamic virtual path (VP) management and fault restoration, we developed a distributed simulation platform for performing our experiments. This platform also had to be capable of other sorts of tests, such as connection admission control (CAC) algorithms, routing algorithms, and accounting and charging methods. The platform was posed as a very simple, event-oriented and scalable simulation. The main goal was the simulation of a working ATM backbone network with a potentially large number of nodes (hundreds). As research into control algorithms and low-level, or rather cell-level methods, was beyond the scope of this study, the simulation took place at a connection level, i.e., there was no real traffic of cells. The simulated network behaved like a real network accepting and rejecting SNMP ones, or experimental tools using the API node.

This paper proposes a traffic engineering scheme using different distribution trees to several multicast flows. We formulate this problem as one with Non Linear programming with discontinuous derivatives (DNLP). The aim is to combine into a single aggregated metric the following weighting objectives: the maximum link utilization, the hop count, the total bandwidth consumption and the total end-to-end delay. Our proposal solves the traffic split ratio for multiple trees. The proposed approach is applied in MPLS networks by allowing the establishment of explicit routes in multicast events. Furthermore, the results obtained with GAMS tools show that several objectives are decreased; the maximum link utilization is minimized. The main contribution of this paper is the optimization model and the formulation of the multi-objective function.

Internet applications such as web or ftp will be satisfactorily supported by a guaranteed minimum throughput service. We propose to build this service in a core-stateless network such as Differentiated Services with an Admission Control (AC) method based on end-to-end measurements, using the first packets of the flow. The whole scheme uses a small set of packet classes (with different discarding priorities), and is therefore simple and scalable. We evaluate the scheme through simulations in several scenarios using TCP flows. Finally, we propose an extension of the method aimed at improving its performance.