The NBS computer networking program, Lecture notes of Computer Networks

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THE NBS COMPUTER NETWORKING PROGRAM

Blanc, R. (^) , J. Heafner, R. Rosenthal, and S. Watkins Institute for Computer Sciences and Technology National Bureau of Standards ABSTRACT This (^) report provides a description of the NBS program in computer networking. The description includes activities in computer network protocol development for large global networks, (^) protocol development and measurement (^) research for local area computer networks, and protocol (^) and format development for computer based (^) office systems. These efforts include the development of standards and the performance of the necessary research to support that standards development. Descriptions of the specific products being developed are also included. Key words: Computer based (^) office systems; computer networking; interfaces; local (^) area networks; measurement techniques; (^) protocols; and standards. 1

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4. LOCAL AREA NETWORKING 13

4.1 Standards 13 4.2 Selection Guidelines 13 4.3 (^) Measurement 14 4.3.1 Measurement and Control Objectives..^14 4.3.2 Approach 14

5. REQUESTS FOR ADDITIONAL INFORMATION 16

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Page 2 standards (^) by the communication service providers attest to this need. Likewise, within the Federal Government there is a strong need to develop communications and higher level protocol standards as well as standards to permit the interchange of documents among computer based office systems. (^) In recognition of these critical needs, NBS has been funded (^) to develop such standards. This program is being (^) conducted in coordination with voluntary standards activities, (^) with the efforts of manufacturers of computing equipment (^) to develop network architectures, with the providers (^) of computer based office systems, and (^) with agencies of the Federal Government. 1.2 Program Structure This report describes the computer networking programs of the (^) Systems and Network Architecture Division which has responsibility (^) for the principal portion of the NBS computer networking program. These programs fall into three major areas; (^) (1) high (^) level computer network protocols (^) , (2) computer based office systems (^) , and (^) (3) local area computer networks. The goal of these programs, collectively, is to provide (^) for distributed computing within the Federal Government (^) and to enable Government organizations to select components (^) of distributed systems based on cost and performance (^) without the constraints imposed by incompatibilities . The computer (^) network protocols program develops high-level network (^) protocols to enable the effective exchange of information (^) among computers as well as between terminals and computers. (^) The computer based office systems program develops (^) guidelines and standards to enable the effective transfer (^) of documents among systems through the electronic interchange (^) of information as well as through media interchange. (^) The local area networking program produces standards (^) and guidelines for the selection of local area data (^) networks, for the connection of devices to local area networks, and for the interconnection of local area networks to (^) national and international global networks. The overall (^) NBS effort has three major components; (1) developing (^) standards and guidelines for the benefit of all agencies (^) within the Federal Government, (^) (2) providing direct assistance (^) on a reimburseable basis to Federal agencies requesting (^) such assistance in technical problems related to computer (^) networking, and (^) (3) conducting computer network research in (^) direct support of specific standards development and (^) agency assistance activities.

Page 3 1.3 (^) Organization Programmatically, the computer network program^ is^ one^ of^ the major components of the computer network and systems interface standards (^) program being conducted by the Center for Computer (^) Systems Engineering of the Institute for Computer (^) Sciences and Technology (ICST). ICST is one of three major (^) operating units (MOU's) of the National Bureau of Standards. (^) The development of standards and guidelines pertaining (^) to the high level computer network protocols, computer (^) based office systems, and local area networks is carried (^) out by (^) the Systems and Network Architecture Division. (^) This work (^) is complemented by the programs conducted in the System (^) Components Division that address the development of (^) base level communication protocols and interface (^) standards to enable the effective interconnection of computer (^) system components as well as the interoperation of computer (^) and data communications systems. Sections (^2) through (^4) of this report describe the three program areas in (^) terms of standards development, advisory services and (^) research activities.

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1. Transport and Session Control Protocols —^ these protocols encompass functions commonly referenced in the (^) transport control layer and session control layer of the ISO Reference Model,^ (1981) .
2. File Transfer and Data Presentation Protocols these protocols, implemented at^ the^ application layer and the presentation layer, provide^ a^ common representation and access method to files,^ (1981).
3. Common Command (^) Language Protocol —^ these commands provide (^) a common user interface applicable to data transfer, remote job entry, and other^ network operations, (^) (1982).
4. Virtual Terminal Protocol —^ this protocol results in a presentation layer protocol that will permit terminals (^) with different character isics to connect to (^) any network computer system, (1982) .
5. (^) Remote Job Entry Protocol —^ this protocol (s) permits batch jobs to be initiated and executed remotely (^) in a network, (1983) .
6. Network (^) Interconnection Protocol —^ this protocol permits the interconnecting of computer networks through a gateway facility, (^) (1983) .
7. Unified (^) Presentation Layer Protocol —^ this protocol (^) integrates other specific presentation layer (^) protocols to provide a uniform data transformation capability, (^) (1983) .
8. Network Interprocess Communication Protocol —^ this protocol facilitates initiation and control of asynchronous (^) processes on distributed computers, (1984) .
9. Distributed (^) Data Protocols — (^) this set of protocols facilitates user access to distributed data in a networking environment, (^) (1985) . As part of the development of these standards, NBS staff is providing (^) briefings to managers and technical experts in Government (^) and industry and has received information from them on (^) their networking activities and developments.

Page (^6) 2.2 Protocol Research And Development In order to (^) develop computer network protocol standards for this dynamic technology it is necessary to perform a certain amount of directed research and development. This section describes NBS research and development efforts which support the protocol standards program. 2.2.1 Protocol Design And Specification Research - The (^) ability to communicate using networks of heterogenous computers requires (^) computer network protocol standards. A family of (^) protocols, organized in a hierarchical relationship, (^) that together satisfy the requirements of a broad spectrum (^) of applications, makes implementations easier and provides (^) greater compatibility. With the growing number of different (^) networks and diversity of uses, it is becoming increasingly (^) more difficult to define efficient protocols that match (^) applications needs effectively. Among the problems of modern protocol design are the following:

1. There are no agreed upon syntax and semantics for expressing (^) the service and functional capabilities of (^) a protocol. Hence, it is difficult for users and designers (^) to devise complex protocols, and readily (^) reach a common understanding of them.
2. There is no (^) taxonomy of applications as they relate to (^) the requirements imposed on protocols. Nor is there a (^) viable methodology in constructing such a taxonomy.
3. There is no procedure for expressing the quantitative (^) and qualitative association of application needs and protocol features.
4. Finally, (^) there is no demonstratable technique for selecting (^) the optimal protocol set based upon sufficiency of need and cost/performance. Resolving (^) these problems would simplify the design of computer (^) network protocol standards. In order to begin answering (^) these questions, NBS has a small research project to (^) construct (^) a methodology for precisely defining the service features (^) provided by a protocol. Initial results from (^) this project (^) have already been obtained. As this methodology develops, it will become important^ in^ defining

Page 8 result in either (^) draft or final reports in calendar year

2.3.1 Impact of Satellite Communications A study has been initiated which will result in an analysis of the impact of satellite communications on network protocol design. This analysis will factor in the impact of high speed, long propagation delay communications on all high (^) levels protocols (levels (^) 4, 5, 6 and 7 in the ISO Reference Model). Recommendations will be made on how protocol design should reflect these considerations. 2.3.2 Impact of Security Considerations The computer network protocol program is not attempting to solve the network security (^) problem, however, it is essential that the protocols (^) be specified in such (^) a way so as not to preclude computer (^) security. A study will soon be initiated to analyze the (^) impact of security on the design of high level protocols. This analysis will result in protocol specifications (^) that can support computer security as security is (^) needed in a particular environment. 2.3.3 The Impact of Tariff (^) Structures It is possible that changing tariff structures in the United States and in other countries will have a significant impact on the design (^) of computer network protocols. It is necessary that (^) the protocols (^) be specified in such a way to maximize the benefits (^) to the users under different tariff structures. A study (^) has been initiated to evaluate the impact of current tariff structures on high level network protocols (^) and to analyze protocol features that should be made dynamic in order (^) to accomodate changing tariffs. 2.3.4 Management (^) Protocols ICST intends to initiate a program to identify and,^ as appropriate, specify network management protocols. This activity will closely parallel associated activities within ISO and ANSI to develop such (^) a set of management protocols. 2.3.5 Guidance on the Use of Standard Protocols ICST intends (^) to develop a set of guidance documents, the first (^) in (^) 1981, to provide assistance in utilizing standard protocols in different application and communication environments. These guidance documents will assist^ users^ in specifying protocols and in selecting the appropriate features (^) of individual protocols for different application environments. (^) In addition, examples will be given of software (^) specifications to interface the transport protocol to different (^) kinds of lower level technologies.

Page 9 2.3.6 Distributed (^) Data Protocols All of the protocol described so far (with the exception of network interprocess (^) conununication) require the user to deal with a (^) "network of computers", that is, the user must be aware (^) that many systems are connected to a network in order to (^) use those systems. Research has been initiated in defining (^) a set (^) of distributed data protocols to locate, structure and present (^) data on behalf of the user without the user having (^) to deal with individual systems. These protocols (^) will use the services of the lower level protocols described (^) herein including the extension of the session control (^) protocol which is called the "network interprocess communication protocol".

Page 11 when (^) operators switch from one formatter to another. A Message (^) Processing Directives Standard is also scheduled for issuance in (^) 1984. It will establish a common set^ of user directives or (^) commands for computer based message systems. This will (^) ensure a minimum common functionality on the part of all (^) computer based message systems considered for Federal (^) use, as well as reduce the amount of retraining required (^) when operators switch from one message system to another 3.2 Guidelines Development A document entitled (^) Guidance on Requirements Analysis for Office (^) Systems has been issued in 1980. It addresses the justification (^) and evaluation criteria for the installation of (^) computer-based office equipment. A (^) FIPS Office Automation (^) Glossary will be issued in 1981. It (^) will (^) ensure the use of a common vocabulary among the individuals (^) involved with office automation, and will provide (^) a uniform basis for the standards development program. 3.3 Laboratory (^) Facilities NBS operates (^) an Office Systems Laboratory to support its program (^) in (^) Computer-Based Office Systems. Included in the laboratory (^) are (^) a number of modern text processing systems. The (^) Office (^) Systems Laboratory shares facilities and space with the (^) Local Networking Laboratory. Nodes on NBSNET (a local area (^) network developed at NBS) connect laboratory terminals (^) to other (^) on-campus computing resources, including the variety (^) of text processing software available in the ICST (^) Experimental Computing Facility. Special purpose I/O equipment (^) is also (^) available for use in the Office Systems Laboratory (^) such (^) as voice recognition (input) equipment and (^) a voice (^) synthesizer (^) (output).

Page 12 3.4 Future Direction Based (^) on the responses to the draft message format standard and (^) interaction between NBS and others working in the area of (^) computer based message systems (CBMS), a number of standards and developmental activities are being initiated. A logical (^) extension to the message format standard is a message (^) presentation standard. This standard will address the user (^) interface to a CBMS with respect to a how a message received (^) by a CBMS is displayed to the user (e.g., the order of presentation (^) of the message fields). There are a number of developmental activities with respect to (^) CBMS which NBS will (^) be addressing in the timeframe of 1981 through 1985. Among these future activities are: an architecture for CBMS, specification of message recipient and (^) originator identities (i.e., addressing), a message prbtocol, and incorporation of multi-media messages into^ the message (^) format standard.