A methodological approach to BISDN signalling performance

Sophisticated signalling protocols are required to properly handle the complex multimedia, multiparty services supported by the forthcoming BISDN. The implementation feasibility of these protocols should be evaluated during their design phase, so that possible performance bottlenecks are identified and removed. In this paper we present a methodology for evaluating the performance of BISDN signalling systems under design. New performance parameters are introduced and their network-dependent values are extracted through a message flow model which has the capability to describe the impact of call and bearer control separation on the signalling performance. Signalling protocols are modelled through a modular decomposition of the seven OSI layers including the service user to three submodels. The workload model is user descriptive in the sense that it does not approximate the direct input traffic required for evaluating the performance of a layer protocol; instead, through a multi-level approach, it describes the actual implications of user signalling activity for the general signalling traffic. The signalling protocol model is derived from the global functional model of the signalling protocols and information flows using a network of queues incorporating synchronization and dependency functions. The same queueing approach is followed for the signalling transfer network which is used to define processing speed and signalling bandwidth requirements and to identify possible performance bottlenecks stemming from the realization of the related protocols

Space-Based Information Infrastructure Architecture for Broadband Services

This study addressed four tasks: (1) identify satellite-addressable information infrastructure markets; (2) perform network analysis for space-based information infrastructure; (3) develop conceptual architectures; and (4) economic assessment of architectures. The report concludes that satellites will have a major role in the national and global information infrastructure, requiring seamless integration between terrestrial and satellite networks. The proposed LEO, MEO, and GEO satellite systems have satellite characteristics that vary widely. They include delay, delay variations, poorer link quality and beam/satellite handover. The barriers against seamless interoperability between satellite and terrestrial networks are discussed. These barriers are the lack of compatible parameters, standards and protocols, which are presently being evaluated and reduced

Saturation routing for asynchronous transfer mode (ATM) networks

The main objective of this thesis is to show that saturation routing, often in the past considered inefficient, can in fact be a viable approach to use in many important applications and services over an Asynchronous Transfer Mode (ATM) network. For other applications and services, a hybrid approach (one that partially uses saturation routing) is presented. First, the minimum effects of saturation routing are demonstrated by showing that the ratio, defined as f, of routing overhead cells over information cells is small even for large networks. Second, modeling and simulation and M/D/l queuing analysis techniques are used to show that the overall effect on performance when using saturation routing is not significant over ATM networks. Then saturation routing ATM implementation is also provided, with important extensions to services such as multicast routing. After an analytical comparison, in terms of routing overhead, is made between Saturation Routing and the currently proposed Private Network-Network Interface (PNNI) procedure for ATM routing made by the ATM forum. This comparison is made for networks of different sizes (343node and 2401 -node networks) and different number of hierarchical levels (3 and 4 levels of hierarchy). The results show that the higher the number of levels of hierarchy and the farthest (in terms of hierarchical levels) the source and the destination nodes are from each other, the more advantageous saturation routing becomes. Finally, a set of measures of performance for use by saturation routing (or any routing algorithm), as metrics for routing path selection, is proposed. Among these measures, an innovative new measure of performance derived for measuring quality of service provided to Constant Bit Rate (CBR) users (e.g., such as voice and video users) called the Burst Voice Arrival Lag (BVAL) is described and derived

ATM in Hybrid Networks

A discussion of the extensions or modifications required to integrate ATM into hybrid networks, i.e. seamlessly interconnected terrestrial and space, wireline and wireless networks will be presented. In this context, the discussion will include: interoperability problems and issues, asymmetric channels, and various data rates. Several issues with proposed standards will also be addressed. A revised version of this technical report has been published in Proceedings of Design SuperCon 1996, Vol. Day One, pp. 1-1 thru 1-13, Santa Clara, CA, January 30-February 1, 1996. </Center

P-XCP: A transport layer protocol for satellite IP networks

Explicit Control Protocol (XCP) is a promising transport layer protocol for satellite IP networks. Nevertheless, two problems of XCP are identified in this paper, namely, low throughput under high link error rate conditions, and output link underutilization in the presence of rate-limited connections. To address the first problem, we propose to maintain the transmission rate of an XCP sender when triple duplicate ACK is detected. To solve the second problem, we propose to adjust the aggregated feedback based on the ratio of the number of rate-limited connections to the total number of connections sharing the link. We then combine our proposed solutions to form a new protocol, called P-XCP. Simulation results show that P-XCP overcomes the two problems of XCP. When packet error rate is over 0.1, P-XCP is shown to enjoy a throughput almost double that of XCP. © 2004 IEEE.published_or_final_versio

Netzwerkmanagement und Hochgeschwindigkeitskommunikation. Teil XIV

Der Interne Bericht enthaelt die Beitraege zum Seminar "Netzwerk-Management und Hochgeschwindigkeits-Kommunikation" des Instituts fuer Telematik (Prof. Dr. Dr. h.c. G. Krueger),das im Sommersemester 1996 zum 14. Mal stattgefunden hat. Die Themenauswahl kann grob in folgende fuenf Bloecke gegliedert werden: 1 - Ein Block ist dem Management von Netzen gewidmet. Hier werden zum einen allgemeine Ansaetze wie TMN und TINA vorgestellt und der Einsatz objektorientierter Techniken im Management diskutiert. Zum anderen finden sich Beitraege zum Management in ATM-Netzen. Themen sind hier das LMI, Aspekte des Accounting sowie das Fehler- und Leistungsmanagement in ATM. 2 - Ein zweiter Block beschaeftigt sich mit Fragen im Zusammenhang von Multicast in ATM-Netzen. Hier werden der Mechanismus der Adressaufloesung mittels des MARS-Konzepts sowie die reihenfolgetreue Auslieferung in Multicast-Gruppen diskutiert. 3 - Ein weiteres Thema ist ein Vergleich aktueller Authentisierungs- und Zertifizierungssysteme und liegt damit im Bereich der Sicherheit von Systemen. 4 - Der vierte Themenbereich des Seminars beschaeftigt sich mit dem ATM-Adaptionsschichtprotokoll SSCOP, das oft zur Unterstuetzung von Signalisierungsmechanismen wie denen des Q.2931 eingesetzt wird. 5 - Schliesslich werden noch Aspekte verteilter Simulationen betrachtet