Open Systems Interconnection Protocols Research Articles

Design of fieldable cross-layer optimized network using embedded software defined radios: Survey and novel architecture with field trials

The proliferation of wireless devices and their ever increasing influence on our day-to-day life is very evident and seems irreplaceable. This exponential growth in demand, both in terms of the number of devices and Quality of Service (QoS) had spawned the concept of cross-layer optimization several years ago. The primary goal of the cross-layer approach was to liberate the strict boundary between the layers of the traditional Open Systems Interconnection (OSI) protocol stack. The objective was to enable information flow between layers which then can be leveraged to optimize the network’s performance across the layers mitigating the challenges due to scarce resources while meeting QoS demands. The initial decade focused on establishing the theoretical feasibility of this revolutionary concept and gauging the effectiveness and limits of this idea. During the next phase, the advent of software defined radios (SDR) accelerated the growth of this domain due to its added flexibility. Even with the immense interest and progress in this area of research, there has been a gaping abyss between solutions designed in theory and ones deployed in practice. To establish this, we first present an elaborate survey of the cross-layer protocol stack literature with emphasis on their maturity scale. Next, we briefly discuss how a commercial off-the-shelf (COTS), low SWaP (Size, Weight, and Power) embedded SDR (e-SDR) was transformed into a standalone, fieldable transceiver. Thereafter, we provide the software design ethos that focuses on efficiency and flexibility such that the optimization objectives and cross-layer interactions can be reconfigured rapidly. To demonstrate our claims, we provide results from extensive outdoor over-the-air experiments in various settings with up to 10-node network topologies. The results from the field trials demonstrate high reliability, throughput, and dynamic routing capability. To the best of our knowledge, this is the first time in literature, a COTS e-SDR has been leveraged to successfully design a cross-layer optimized transceiver that is capable of forming an ad hoc network that provides high throughput and high reliability in a ruggedized, weatherized, and fieldable form factor.

Why Then Did the X.400 E-mail Standard Fail? Reasons and Lessons to be Learned

The X.400-series of recommendations specifies the elements, protocols, and services of the e-mail system associated with the Open Systems Interconnection (OSI) protocol stack. The paper looks at the various reasons that led to X.400's failure to gain the widely expected level of market acceptance. A brief literature review suggests that common explanations for success in a standards battle cannot explain the demise of X.400. The same holds for two popular explanations for the victory of Internet over OSI. Therefore, alternative reasons are proposed and discussed, including poor timing of the standardisation activity, inadequate first implementations, and an ill-advised paradigm shift that occurred in the cause of events. Finally, some lessons to be learned for the future are identified.

Partial ASN.1/BER decoding scheme in a multiprocessor environment

In many cases, the most time-consuming part of the Open Systems Interconnection (OSI) protocol stack is the encoding and decoding of transfer syntax done in the presentation layer. The conventional ASN.1/BER decoding scheme runs on a whole Presentation Protocol Data Unit (PPDU). To overcome this problem, we present a new ASN.1/BER decoding scheme called Partial Decoding. The Partial Decoding scheme allows us to start decoding partially on each segment of a PPDU before a whole PPDU has been received. The measures show that the new scheme has a performance improvement as high as 40% over the conventional decoding scheme at large message size. Parallel processing for the network layer through the presentation layer is also used for a high performance protocol implementation on the basis of the proposed scheme.

The (un)revised OSI reference model

In 1988, SC21, the ISO committee responsible for the Open Systems Interconnection (OSI) Reference Model, determined that it was time to undertake revising ISO 7498-1, The Basic OSI Reference Model. Since the model had been published in 1984, this was in accordance with ISO practice of reviewing and revising standards every five years, and there was good reason for considering the task. Over the intervening five years, the groups developing the OSI protocols had raised many questions about the architecture and these had been answered and documented in the Approved Commentaries [1994]. Many of these commentaries contained information that could be usefully incorporated into the Reference Model itself. In addition, the addendum describing connectionless mode, i.e. datagrams, had been completed several years before and needed to be incorporated. There was also considerable demand for interworking connection-mode and connectionless mode communication, something not supported by the Reference Model or any architecture. Also, when the original version of the Reference Model was frozen about 1983 some aspects of OSI such as the upper layers were not well understood and were only described in the most cursory manner. And while connection-mode and connectionless mode had been brought within OSI, there was no indication as to how broadcast and multicast were to be handled. Thus, the revision might be able to provide a more comprehensive description of these areas.This paper describes how the revision was carried out, describes the changes and additions that were made, considers the effect and contribution this revision has made to our understanding, and describes the outstanding issues that were not addressed by this revision.

Efficient Encoding Rules for ASN.1-Based Protocols

Abstract syntax notation one (ASN.1) describes the data structures of protocol messages. In the open-systems interconnection (OSI) standards, the manner in which the data values are encoded is negotiated at the start of communications. In principle, there can be several different ways to encode the data values. Until recently, however, there was only one OSI-standardized way to do so. This standard was the basic encoding rules (BER) for ASN.1. Almost all OSI application-layer standards have specified their protocol messages in ASN.1, as have several integrated services digital network (ISDN) signaling standards based on OSI protocols. All have mandated use of the BER for their encoding. Many commercial products are also available that encode and decode protocol messages, as specified in ASN.1, to and from BER-encoded bit streams. Experience with the BER has led to criticism of their efficiency, particularly for real-time applications. Thus, there has been a move to standardize alternative encoding schemes that address these efficiency concerns. This paper introduces the alternative encoding schemes and compares them to the BER. The distinguished encoding rules (DER), canonical encoding rules (CER), packed encoding rules (PER), and lightweight encoding rules (LWER) are the alternative encoding schemes discussed.

SORTEZ: a relational translator for NCBI's ASN.1 database.

The National Center for Biotechnology Information (NCBI) has created a database collection that includes several protein and nucleic acid sequence databases, a biosequence-specific subset of MEDLINE, as well as value-added information such as links between similar sequences. Information in the NCBI database is modeled in Abstract Syntax Notation 1 (ASN.1) an Open Systems Interconnection protocol designed for the purpose of exchanging structured data between software applications rather than as a data model for database systems. While the NCBI database is distributed with an easy-to-use information retrieval system, ENTREZ, the ASN.1 data model currently lacks an ad hoc query language for general-purpose data access. For that reason, we have developed a software package, SORTEZ, that transforms the ASN.1 database (or other databases with nested data structures) to a relational data model and subsequently to a relational database management system (Sybase) where information can be accessed through the relational query language, SQL. Because the need to transform data from one data model and schema to another arises naturally in several important contexts, including efficient execution of specific applications, access to multiple databases and adaptation to database evolution this work also serves as a practical study of the issues involved in the various stages of database transformation. We show that transformation from the ASN.1 data model to a relational data model can be largely automated, but that schema transformation and data conversion require considerable domain expertise and would greatly benefit from additional support tools.

CMISE functions and services

The common management information service element (CMISE), an application service element (ASE) developed to support the management application of the Open Systems Interconnection (OSI) applications layer, is discussed. It was developed in response to the need to monitor and control the health of OSI communications entities. Similarly, the simple network management protocol (SNMP) was developed in the Internet community to manage network resources. Although CMISE was developed to manage resources such as OSI protocol entities, its applicability in managing the telecommunication network elements has been accepted in CCITT and ANSI T1 standards because of its powerful features.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Standard conformance test specification language TTCN

The International Standards Organization (ISO) has defined a protocol test language called TTCN (Tree and Tabular Combined Notation) to specify abstract test suites for Open Systems Interconnection (OSI) protocols. TTCN combines a tree notation for dynamic behaviour description with a tabular representation of various language constructs. TTCN allows tabular constraints to enforce values on the Abstract Service Primitive (ASP) or Protocol Data Unit (PDU) parameters. For application layer protocols, Abstract Syntax Notation One (ASN.1) constraints are used. Dynamic behaviour description in TTCN is shown to address many important aspects of conformance testing such as modularity support in terms of test cases, steps and default behaviour tables and sophisticated timer management. TTCN has a machine processable form called TTCN-MP that defines all the TTCN syntax using BNF. Semantics of the tests specified in TTCN is operationally defined rendering TTCN almost a formal notation.

A base for portable communications software

The emerging international standards for interconnecting computers will be important in IBMs future plans. The Open Systems Interconnection (OSI) protocols are already part of IBMs Systems Application Architecture® (SAA™), implying that they will be implemented across the dissimilar SAA operating systems. Building these complex OSI protocols is costly, and additional expense is involved in verifying conformance and interoperation with other systems. “Porting” a common implementation of these protocols to all SAA systems offers major cost savings, but the difference between systems and the need for high-performance, robust implementations poses problems. The OSI/Communications Subsystem Base solves many of these problems in a general way that may apply to other layered protocols and other systems. The Base provides all necessary operating system services to support the layered communications protocol machines of OSI and allows access to the I/O services of the native operating system as required. This paper discusses the sophisticated communications-oriented environment provided by the OSI/Communications Subsystem Base, which includes multiple threads, back-pressure flow control, resource monitoring, layer modularity, and steps to minimize process switches and data copying. The paper is addressed primarily to systems engineers and communications architects interested in OSI and portability in general.

High-speed transport components

An overview of research of high-speed transport components is given. High-speed protocols as well as high-speed implementations are considered. The use of parallelism to increase the performance of communication nodes is considered. A parallel implementation of Open Systems Interconnection (OSI) protocols on transputer networks based on the parallel concepts discussed is described. Selected performance values of the implementations are presented. The outlook on the design of high-speed transport components for future communication systems is examined.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Technology 1991: data communications

Significant developments during 1990 are examined, and future trends are delineated. Two major events were the rapid acceptance by end users of the 10BASE-T standard for Ethernet interconnections using unshielded twisted-pair wiring and the widespread acceptance of the fiber distributed data interface (FDDI) by corporate planners and MIS (management information system) people, as well as government planners, as the way to wire the corporate backbone. 1990 also saw commercialization begin of the FDDI interface by which data is transmitted on an optical-fiber network at 100 Mb/s rates. The development of twisted-pair wiring for Ethernet and FDDI will lead to integration of Ethernet. Token Ring, and FDDI local networks in one concentrator in one wiring closet, while the pace of growth of the LAN market continues to accelerate. The seven layers of the Open Systems Interconnection (OSI) protocol received a big boost last year from the US government, and it is likely to become the routine way of organizing data networks worldwide.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Communication protocol standards for space data systems

The main elements and requirements of advanced space data networks are identified. The communication protocol standards for use on space missions during the coming decades are described. In particular, the blending of high-performance space-unique data transmission techniques with off-the-shelf open systems interconnection (OSI) protocols is described.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Government Open Systems Interconnection: Profile in progress

The emergence of Open Systems Interconnection protocols, as specified within the U.S. Government Open Systems Interconnection Profile (GOSIP) Federal Information Processing Standard (FTPS), provides both an opportunity for, and a means of achieving, interoperability within multi‐vendor networks. The GOSIP can easily benefit inexperienced users, yet provides the flexibility to serve more sophisticated users. The standard mandates specifications that will be met by a multitude of vendor products, with initial offerings already available. While meeting a useful set of initial networking needs, the FTPS will evolve to include new applications, improvements to the initial applications, new network technologies, and major new functions. GOSIP will permit government agencies to gain better control over their computer network procurements, accruing greater and greater cost savings as the number of government computer networks increases.

Protocol specification for OSI

The collection of Open Systems Interconnection (OSI) standards are intended to allow the connection of heterogeneous computer systems for a variety of applications. In this context, the protocol specifications are of particular importance, since they represent the standards which are the basis for the implementation and testing of compatible OSI systems. This paper has been written as a tutorial on questions related to protocol specifications. It provides certain basic definitions related to protocol specifications and specification languages. Special attention is given to the specification formalisms used for OSI protocol and service descriptions, including semi-formal languages such as state tables, ASN.1 and TTCN, and formal description techniques (FDTs) such as Estelle, LOTOS, and SDL. The presentation is placed within the context of the general protocol and software development life cycle. An outlook to available methods and tools for partially automating the activities during this cycle is given, and ongoing research directions are discussed.

Conformance Testing Methodologies for OSI Protocols

As open systems interconnection (OSI) protocol standards mature and systems are developed to implement them, facilities to test protocol implementations for conformity to relevant international standards and recommendations are becoming the key to vendor interoperability. This paper examines the test methods applicable to OSI conformance testing as defined by the International Organization for Standardization (ISO) and the International Telegraph and Telephone Consultative Committee (CCITT). The advantages and disadvantages of each test method are discussed. Each test method is analyzed in terms of its technique in providing synchronization between the test system and the system under test (SUT), and its ability to supply a controlled environment for comprehensive protocol testing. We also discuss the applicability of each test method to different OSI protocols, and the generic aspects oftest system architecture common to all test methods. Specific attention is paid to those test methods that will be used to test X.25 implementations and network management protocols.

Analysis of transport measurements over a local area network

Measurements of the end-of-end delay and maximum throughput are reported for a typical implementation of the bottom four layers of the Open Systems Interconnection (OSI) protocols. These comprise the transport, network, data link, and physical protocols. An overview of the four protocols is given, and the experimental environment is described. The measurement results are discussed, and some of the implementation factors that affect the performance of OSI protocols are identified. >

Office communications

A short overview of the Open Systems Interconnection protocol standards related to office communications, covering approved and ongoing standardization work in the International Organization for Standardization, the Consultative Committee on International Telephone and Telegraph, and the European Computer Manufacturers' Association, is given. The relationship between office communications and the OSI Reference Model is discussed, and the Distributed Office Architecture Model is presented, establishing a common set of guidelines and requirements to be observed in the development of distributed office applications. The principal applications of this class are then described in turn, including those dealing with Message Handling, Document Filing, Document Printing and Remote Data Access. The supportive Referenced Data Transfer and Directory applications are also discussed, as are security considerations as they relate to distributed office applications. The paper concludes with a discussion of plans for future standardization activities.

Structured systems analysis methodology for design of an ATM network architecture

The asynchronous transfer mode (ATM) network design problem is treated as a resource-allocation problem. Traffic control is applied to different entities: packets, bursts, calls, and flows. Each of these entities can be controlled locally, within an exchange, or globally, at the network level. This gives rise to a multistrata architecture, where the resource-allocation stratum is defined both by the layer of traffic flow and the control level. Dedicated and virtual connections can be set up in all strata: for bursts, calls, subscriptions, and flows, at the exchange, subnetwork, and network levels. The open systems interconnection protocols are used to map heterogeneous user entities onto uniform network entities. The critical load is defined, which is where burst and call fluctuations begin to result in long queues and big packet delays. The critical load is used to determine thresholds, at the network and exchange level, for the number of virtual or dedicated connections which can be established in each traffic class. >

Testing OSI (Open Systems Interconnection) protocols at the National Bureau of Standards

Testing OSI (Open Systems Interconnection) protocols at the National Bureau of Standards

Design and implementation of a LAN monitoring tool

The seven layer Open Systems Interconnection (OSI) protocol reference model has achieved the goal of dividing network operations into distinct implementation modules. High level protocols shield the user from activities occurring at the lower levels. Unfortunately, these high level protocols also keep the user from seeing low level problems that can cause insidious network events. The LANalyzer EX 5000E is an Ethernet network analysis tool created to provide insight into network problems, and to assist in the debugging of network applications and protocols. This paper discusses the conception and implementation of the EX 5000E. Design tradeoffs are addressed, and the hardware and software architecture of the product is explained.