Staged refresh timers for RSVP

The proposed uses of the resource reservation protocol (RSVP) now extend beyond reserving resources in Internet protocol (IP) networks to being a generic signaling protocol for generalised multi-protocol label switching (GMPLS). In any implementation of RSVP, there are a number of discretionary timing parameters, the values of which affect the efficacy of RSVP in establishing and maintaining reservations/connections. This work frames the interactions between key RSVP timing parameters and performance metrics as a multi-objective optimisation problem which, due to its intractable nature, is tackled using a reputable multi-objective evolutionary algorithm. It is shown that this approach is a feasible means of exploring many of the innate tradeoffs in soft-state protocols such as RSVP. This approach facilitates an extensive comparison of a number of variants of RSVP: standard RSVP, RSVP featuring the recently standardised retransmission algorithm and two subsequent variants of this algorithm, supporting the asymmetric delivery of RSVP control messages. These RSVP variants are compared in terms of multiple performance metrics under a number of different exemplar network conditions, giving insight into their relative merits. Furthermore, the relative significance of the different timing parameters is investigated and their most expedient values determined.

The goal of the Resource Reservation Protocol (RSVP) is to establish Quality of Service information within routers and host computers of the Internet. This paper describes a model of RSVP and presents the analysis approach and results. A large part of RSVP is modelled using Coloured Petri Nets. The model provides a clear, unambiguous and precise definition of the considered features of RSVP, which is missing in the current protocol specification. The model is analysed for a set of general properties, such as correct termination, and a set of RSVP specific properties defined in this paper. The properties are checked by querying the state graph and its associated strongly connected component graph. As a first step, we analyse RSVP under the assumption of a perfect medium to ensure that protocol errors are not hidden by rare events of the medium. The results show that the RSVP model satisfies the defined properties.KeywordsModel CheckInternet ProtocolFlow SpecificationStrongly Connect ComponentReservation RequestThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

This document describes a number of mechanisms that can be used to reduce processing overhead requirements of refresh messages, eliminate the state synchronization latency incurred when an RSVP (Resource ReserVation Protocol) message is lost and, when desired, refreshing state without the transmission of whole refresh messages. The same extensions also support reliable RSVP message delivery on a per hop basis. These extension present no backwards compatibility issues.

This paper describes recent experiences with evaluating and implementing advanced communication protocols on top of ATM. First, experiences and performance results with conventional TCP/IP over ATM based on Digital Equipment’s Gigaswitch/ATM are reported. Moreover, the behaviour and performance of application-level remote procedure call protocols with mass data transfer extensions over ATM is discussed. It becomes obvious that current protocols must be tuned specifically in order to exploit ATM performance. Moreover, the lack of reservation facilities, especially in heterogeneous environments, has been identified as another significant problem; currently, no quality of service guarantees are possible.In order to address the quality of service issues, the second part of the paper describes advanced concepts and an implementation of IPng (IP next generation) and RSVP (Resource Reservation Protocol) over ATM. Particular emphasis is put on the problem of mapping quality of service and traffic parameters in an adequate way. Moreover, the issue of address mapping from IPng onto ATM is also discussed. First implementation results in these areas are presented. The paper finally concludes with an outlook to future work in the area of resource reservation in advance.KeywordsATMTCP/IPIPngRSVPquality of serviceresource reservationperformance measurements

Although the mobile agent paradigm provides great potential advantages ever traditional approaches in distributed computing applications, there are still several issues to be addressed before the technology can be widely accepted. The performance of the communication protocol is one of the critical issues in mobile agent systems. A practical communication protocol for mobile agents must satisfy three basic requirements: location transparency, reliability and efficiency. Although many communication protocols have been proposed for mobile agent systems and most of them are location transparent, these protocols usually compromise some aspects of reliability and efficiency. In this research we develop a communication scheme for efficient location tracking of agents and reliable message delivery in mobile agent systems by using a proxy-based scheme. The location update and message delivery protocols are developed and shown to be reliable even when agents migrate during message delivery. A simulation model is developed to estimate the performance relative to a (nonproxy-based) home-server protocol. Sensitivity analysis is used to reveal the important circumstances (domain/agent dimensions and exogenous demand/movement characteristics) for efficient communication performance.

Patient monitoring is becoming a requirement for offering a better healthcare to an increasing number of patients in nursing homes and hospitals. During the monitoring, vital signs of patients could fluctuate significantly and/or match certain undesirable patterns and therefore alerts or emergency messages must be delivered to healthcare professionals. There has been some work in using infrastructure-oriented wireless networks for transmission of emergency messages, however, the network coverage and reliability of message delivery have not been satisfactory. To overcome these, we propose that ad hoc networks can be formed among patients’ devices for improved transmission of emergency messages. We also propose several design enhancements to improve the quality and coverage of patient monitoring. The performance results for the proposed ad hoc network based architecture show that reliable message delivery and low monitoring delays can be achieved by using multicast or broadcast-based routing schemes.

In distributed systems, a group of processes are cooperated to execute an application program. A group is established among multiple processes and only processes in the group communicate with each other. This type of group communication is named intra-group communication. The communication system has to support the reliable intra-group communication in the presence of the process fault. In order to tolerate the process fault, each process in the group is replicated into a collection of multiple replicas named a cluster. In this paper, we would like to propose a new intra-group communication protocol which supports the causally ordered delivery of messages for the processes within the group. In addition, the protocol supports the reliable delivery of messages in the presence of the Byzantine faults of the processes.

Reliable delivery of messages is an important problem that needs to be addressed in distributed systems. In this paper we briefly describe our basic strategy to enable reliable delivery of messages in the presence of link and node failures. This is facilitated by a specialized repository node. We then present our strategy to make this scheme even more failure resilient, by incorporating support for repository redundancy. Each repository functions autonomously. The scheme enables updates to the redundancy scheme depending on the failure resiliency requirements. If there are N available repositories, reliable delivery guarantees will be met even if N-1 repositories fail.

In this paper, we exploit the heterogeneity of wireless channels and propose an efficient opportunistic cognitive routing (OCR) scheme for dynamic spectrum access (DSA) networks. We first introduce a novel routing metric by jointly considering physical characteristics of spectrum bands and diverse activities of primary users (PU) in each band. To effectively explore the spectrum opportunities, a proper channel sensing sequence for fast and reliable message delivery is determined by secondary users (SU) in a distributed way. We then develop a greedy forwarding scheme that SUs can select the next hop relay based on the geometry information and channel access opportunity of their one hop neighbors. For the proposed OCR, as routing control messages are locally exchanged, SUs can efficiently make the routing decision and opportunistically access the available channels. We further evaluate the performance of OCR via extensive simulations. It is shown that our proposed scheme outperforms existing opportunistic routing schemes in DSA networks by exploiting the heterogeneity of spectrum bands for opportunistic channel access.

Wireless messaging, in the form of two-way paging, is an integral part of universal Personal Communications Services (PCS). Basic wireless messaging services include providing reliable (acknowledged) message delivery, reply capabilities, and message origination from a messaging device. Many more advanced services can also be envisioned. Wireless networks and end devices impose many limitations on system design. To overcome the problems caused by such an environment, we have introduced network based proxies, called user agents, to assist simple end devices, and a novel way to define messages, called flexible messages, so that advanced messaging services may be offered. In this paper, we describe how user agents and flexible messages assist in providing messaging services in the Pigeon two-way messaging research prototype at Bell Laboratories.

RelM: reliable multicast for mobile networks

No doubt, the usages of mobile agent and mobile phone technologies are rapidly increased. The mobile agent has a promising room in the industry area. Unfortunately, this technology faces some security problems from mobile agents and hosts sides. Two of the fundamental issues in designing protocols for message passing between mobile agents (MAs) are tracking the migration of the target agent and forwarding messages to it. Even with an ideal fault-free network-transport mechanism, messages can be dropped during MA migration. Therefore, in order to provide reliable message delivery, protocols need to overcome message loss caused by asynchronous operations of agent migration and message forwarding. As mobile devices and third generation mobile networks have become a reality, location based services are thought to be a major growing area. Mobile devices are given context sensitiveness so that they can be aware of the users/services surrounding physical environment and state. In this paper we propose message forwarding approaches, namely push and pull, are explored to design adaptive and reliable message delivery protocols.Also location aware services scheme by using an agency, which helps in discovering the required services for the mobile users. The agency consists of five agents: Manager Agent (MA), Route Monitoring Agent (RMA), Local Service Management Agent (LSMA), Global Service Management Agent (GSMA) and Area Monitoring Agent (AMA).

In this paper, we address the relation between message delivery delay and reliability for the communication between a vehicle and a road side unit (RSU). We focus on sparse or low density vehicular ad hoc networks (VANETs), where timely message delivery and reliable transmission are of significant importance. We present an exact message delivery delay distribution for a two-lane road, where vehicles in one direction act as message carriers for the ones in the other direction and have the freedom to leave the road from randomly distributed exits with a certain probability. Our analysis offers a tool for an intelligent transportation system (ITS) service provider to determine the minimal separation between two consecutive RSUs for meeting a probabilistic requirement of the message delay. Simulation results show the accuracy of our analysis.

IEEE- and ASTM-adopted Dedicated Short Range Communications (DSRC) vehicle safety-related communication services, which require reliable and fast message delivery, usually demand broadcast communications in vehicular ad hoc networks (VANETs). In this paper, we propose and justify a distributive robust scheme for DSRC one-hop safety-critical services. The new scheme enhances broadcast reliability using dynamic receiver-oriented packet repetitions and mini-slot within DIFS in IEEE 802.11 for one-hop emergency warning message dissemination. In addition, we investigate the reliability and performance of the proposed broadcast scheme for DSRC VANET safety-related services on highway analytically and by simulations. The analytic model accounts for the impact of the beacon message broadcast and the fading channel conditions on the reliability and performance.

Dedicated short-range communications (DSRC) is one of the key technologies enabling safety-critical applications for intelligent transportation system (ITS). Considering the significance of such safety-of-life applications, it is of utmost importance to guarantee reliable delivery of basic safety messages (BSMs). However, in accordance with a V2X network being inherently dynamic in key aspects such as vehicle density and velocity, the networking behavior of a DSRC system is usually highly complicated to analyze. In addition, the United States Federal Communications Commission (US FCC) recently proposed the so-called “5.9 GHz band innovation,”which includes a plan to reduce bandwidth for DSRC to 10 MHz at best from 75 MHz. Motivated from these challenges, the necessity of “lightening”load of a DSRC network has become essential to keep safety-related operations from performance deterioration. To this end, this paper proposes a protocol that prioritizes transmission of a BSM from a vehicle according to the level of accident risk of the vehicle. The proposed protocol uses the distance of a vehicle from a danger source as the metric to determine the priority for transmission. Our results show that this protocol effectively prioritizes the transmission opportunity for dangerous vehicles, and hence results in higher performance in terms of key metrics-i.e., average latency, packet delivery rate (PDR), and inter-reception time (IRT).