File Transfer Service Research Articles

Handling of QoS characteristics

Network users can apply principles of software evaluation to networking services. We introduce a specific method for measuring important service characteristics. The method and the measurement procedure allows to compare the actual characteristics of service quality with the required characteristics. Since the approach can easily and efficiently be implemented in any organisation, it may help-end-users in choosing network service providers. GMD, the German National Research Center for Computer Science, provided from 1991 to the end of 1993 the “German Networking, Research and Information Centre” (GeNeRIC) for electronic mail, file transfer, remote login, packet switching, and information services in a multi-protocol environment (OSI, EARN/BITNET, Internet). The users and the contractors required a guaranteed quality of service (QoS). Provider-specific approaches were chosen to achieve this, since there is still no accepted definition of QoS characteristics. GMD also participated in the ESPRIT project “Software Assessment and Certification Program Europe” (SCOPE) from 1989 to 1993. In this paper, we show how the software evaluation method developed in SCOPE can be used to handle the QoS characteristics of networking.

International links for research collaboration

Abstract The European and US Research Communities have been linked for fifteen years by various communication channels. Recently, it has been decided to upgrade some of the connections to higher speed links. These links can support not only the conventional services like terminal access, file transfer, electronic mail and directory services, but also video conferencing using compressed video. Moreover the channels are being provided by different agencies with different missions and support different protocols and services. Some of the technical aspects of the links, and the policy and administrative questions which have had to be resolved, are discussed in this paper; there is particular emphasis on the UK-US link, but the discussion includes extension to other European countries. We then discuss at length the provision of video conferencing facilities over the UK-US channel, and consider how such facilities could be provided on a broader European basis.

Operations and management of a campus packet network

The operation and management of the Kansas University Packet Switch Network (KUPSN),which provides interactive and file transfer services to its users, is discussed, focussing on the problems encountered and solutions developed. Areas of network management of particular concern are identified, and tools developed to deal with them are described. Management system integration and the evolution of problem-handling procedures are discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Upgrading the intercontinental links for research collaboration with emphasis on the UK-US scene

The UK and US Research Communities have been linked for fifteen years by various communication channels. Recently, it has been decided to upgrade the connection to a 512 kbps link. The link is to support not only the conventional services like terminal access, file transfer, electronic mail, and directory services, but also video conferencing using compressed video. Moreover, the channel is being provided by different agencies, which have different missions, support different protocols, and different motivations. Some of the technical aspects of the link, and the policy and administrative questions which have had to be resolved, are discussed in this paper. A brief status report on other European-US links for speeds higher than 64 kbps is given also.

OSI PRODUCT SURVEY

As OSI standards are becoming finalized, computer manufacturers and vendors are beginning to provide networking solutions based on OSI protocols. Products which implement OSI protocols are available from most major suppliers. They cover all seven layers and support several technologies and applications. Technologies supported include X.25 networks and various types of local area networks; applications supported are file transfer, virtual terminal, message handling, and directory services. Several projects are underway to promote conformance and interoperability testing of OSI products. This article describes some of these testing projects and a sample of OSI products available.

Process control: How to process distributed data in less than a second?

Physical and natural distribution is also a property for large process control realisations. The next step in automatization concerns the optimized designs of data flows and data processing on the floor. The most performant architecture with regards to database distribution, is certainly to distribute data, that is, to consider the usage of cooperating servers. ISO is actually working on a communication support to distributed transactions that must be atomic. The Distributed Transaction Processing protocol is an open protocol in that it is a support to the transaction concept but is not meant to interfer whatsoever in the containt of the transaction. Between the times a transaction starts and terminates, an application process may use indifferently RDA services, MMS services or file transfer services. Presently, the so called application layer may be considered as a pool of protocols that offer specific services to the application process. However, there remains a work to be accomplished in ISO under the pression of network users with regards to interoprability between protocols. This is a goal that can be achieved in the determination of the standardized so called protocol “profils” options. To this aim, all potential users should participate in this work at SPAG, in ESPRIT projects within the European Community and in ISO working groups.

A Performance Model Of Packet Switched Networks With Bursty Traffic

AbstractTransport of bursty traffic is becoming increasingly in demand in telecommunication networks for still image transfer, facsimile, electronic mail and other file transfer services. End-to-end delay is an important performance criterion for this traffic, particularly in real time applications such as when it is an accompaniment to a telephone conversation or the response to a data base query. Packetized transport of this traffic is desirable from the viewpoint of bandwidth efficiency so long as it meets the end-to-end delay requirements. This paper presents a new, computationally efficient, analytical modelling technique for performance analysis of bursty traffic in a packet switched network which allows estimation of end-to-end delay. A comparison of the analytical results with a simulation shows that the analytical model is within the 90 per cent simulation confidence intervals for a large range of parameter values. The model is based on approximate Mean Value Analysis of a closed network in conju...

A New File Transfer Protocol

We describe a new File Transfer Protocol (FTP) that provides a simple and efficient way of transferring files between heterogeneous systems, such as the UNIX™ operating system, Duplex Multi-Environment Real-Time (DMERT), and IBM/MVS. This FTP has been adopted as an AT&T standard. In this protocol, global functions requiring close coordination are separated from local functions. Functions that require global coordination are mandatory parts of the protocol and must be implemented uniformly. Local functions, such as file management and user interface, can be adjusted to local needs and might even be optional. This results in a flexible protocol that can be implemented at various levels of complexity. Thus, FTP implementations can range from very simple ones that provide basic file transfer service to highly complex ones that provide extensive security checking and allow a variety of file management services.

Anticipating the ISO file transfer standards in an open systems implementation

Abstract This paper describes a special case of conversion belonging to the Application Layer of the ISO Reference Model for Open Systems Inter-connection. It discusses the construction of a module, which provides a File Transfer Service as that defined in the ISO Working Draft on File Transfer, Access and Management (FTAM), ISO TC 97/SC 16 N1190, N1222, N1223, N1224. It is described how the semantics of the ISO FTAM service is mapped onto an existing and widely accepted interim FTAM protocol, the Network Independent File Transfer Protocol NIFTP-B(80) (the ‘blue book’). The intended goal of this approach, as demonstrated in the Danish PAXNET project, is to provide new FTAM implementations which bridge the current gap between existing implementations and the anticipated ISO/OSI FTAM service. The paper shows, how the requirements of ‘open working’ in the sense of the NIFTP-B(80) may be met in an actual implementation. Some general problems, characteristic for the construction of gateways, are illustrated.

Anticipating the ISO file transfer standards in an open systems implementation

This paper describes a special case of conversion belonging to the Application Layer of the ISO Reference Model for Open Systems Inter-connection. It discusses the construction of a module, which provides a File Transfer Service as that defined in the ISO Working Draft on File Transfer, Access and Management (FTAM), ISO TC 97/SC 16 N1190, N1222, N1223, N1224. It is described how the semantics of the ISO FTAM service is mapped onto an existing and widely accepted interim FTAM protocol, the Network Independent File Transfer Protocol NIFTP-B(80) (the ‘blue book’). The intended goal of this approach, as demonstrated in the Danish PAXNET project, is to provide new FTAM implementations which bridge the current gap between existing implementations and the anticipated ISO/OSI FTAM service. The paper shows, how the requirements of ‘open working’ in the sense of the NIFTP-B(80) may be met in an actual implementation. Some general problems, characteristic for the construction of gateways, are illustrated.

Managed file distribution on the universe network

The file distribution system on the Universe Network consists of a distributed set of co-operating agents which provide clients with a reliable bulk file collection, transfer and delivery service. The agent systems incorporate specialised techniques for optimizing use of the satellite channel, as well as making available facilities for broadcast file distribution. The distributed system architecture and protocols are described, with emphasis on the separation of control and data transfer. A detailed presentation is given of the way in which agents interact with both hosts and other agents to achieve both reliability and robustness in the face of breaks in host or network availability. A description is given of the special transfer methods used and some of the possible applications for such a system. An indication is given of possible future developments to enable evolution from an experimental to service system.

A file transfer protocol and implementation

This paper presents a file transfer service in a heterogeneous computer network (HMINET). The basic architecture models are presented, the file transfer protocol is described and the implementation in the HMINET is shown with the functional capabilities and the command structure. A transfer of files between different computer system can be regarded as a service, which is divided into four steps: A: access to a file, which is administrated in a File Management System (FMS), residing on one computer system B: transfer the file data by any transport medium C: creation of a file copy in another EMS D: additional operations on the transferred file, e.g. print out or conversion The usual case of file transfer (FT) between different computer systems is an offline transport by means of any storage medium (disks, tapes, etc.). Some disadvantages arise by this method: - offline transfer takes a long time - incompatibility of peripheral devices, storage medium and dat a representation can make file transfer impossible or lead to an additional overhead - for step A and C the user must be familiar with the control languages of every participated operating and file management system - additional operations on the transferred file must be organised under the system control of the destination host A lot of advantages offers a File Transfer Service, integrated in a network, which links together the above mentioned computer systems (hosts): - with a reliable transport system in the network a fast online transfer of the file data can satisfy step B - step A and C are controlled by the File Transfer Service with only one standard interface to the user - additional operations on the copied file can he managed during the transfer of the data (conversion of file structure, file dat a and subsequent operations e.g. print) - peripheral device support by involved operating and file management system under File Transfer Service control The HMINET is a private star-shaped, heterogeneous network, which connects 22 process control computers and 3 mainframes. One basic function in that computer network is such a file transfer service. Typical applications of this service are: Copy of data files from and to mainframes and process control computers Transfer of programms and runable modules Remote Job Entry and remote spool services, etc.