Showing papers on "Media access control published in 1989"

FDDI bit error rate tester

Abstract: Methods and apparatus are set forth which facilitate continuous bit error rate monitoring at the physical (PHY) management layer in a Fiber Distributed Data Interface (FDDI), duel token ring network. The monitoring is performed using existing line status information from PHY. Simple error detection logic, in combination with an error counter and a timer, is used to detect errors during active or idle line state conditions, independent of Media Access Control (MAC) layer support.

Implementation of physical and media access protocols for high-speed networks

Abstract: Existing protocols for high-speed local area networks (HSLANs) and metropolitan area networks (MANs) are dealt with from an implementation standpoint. Emphasis is put on the lowest layers of the ISO OSI (Open Systems Interconnection) Reference Model, i.e. the physical layer and media access control sublayer of the data-link layer. Seven representative state-of-the-art HSLAN and MAN media-access protocols are surveyed and classified, and implementations of these protocols that are used in prototype and commercial networks are analyzed. The complexity, technology, and performance of the implementation are described and compared. >

FDDI-II operation and architectures

Abstract: FDDI (fiber distributed data interface) provides both the high bandwidth and low latency needed to match the increased capacity of future personal computers, at least for traditional LAN applications. The improved latency, however, is not low enough for a true multimedia LAN. What is needed is an access method that simplifies the interface to video and sound networks as well. FDDI-II is an extension of FDDI that provides this additional service. The authors discuss the FDDI-II architectural models and operations as defined in the FDDI hybrid ring controller (HRC) specification and present example implementation architectures for FDDI-II systems. It is shown that FDDI-II implementations can be quite simple, with the extensions to an FDDI implementation requiring only variations on the time-division multiplexing circuitry that has already been well-developed by telecommunication designers. >

LAN interconnection via frame relaying

Abstract: The authors begin with a discussion of the criteria for evaluating wide-area networks (WANs) used to interconnect remote bridges. Then they assess various WANs, point out the advantages of frame relaying, and describes this experience with operating implementation interconnecting token-rings via a prototype frame relay. The quality of a bridge service is considered to be the quality of MAC (media access control) service as seen by end-stations on different LANs that are bridged either directly by a single bridge or indirectly via multiple bridges and associated LANs. It depends critically on the route (which is dependent on the network topology) between the source and destination LANs and the quality of service provided by the individual brides and, in the case of remote bridges, WANs along the route. >

SNMP over Ethernet

Abstract: This memo describes an experimental method by which the Simple Network Management Protocol (SNMP) can be used over Ethernet MAC layer framing instead of the Internet UDP/IP protocol stack. This specification is useful for LAN based network elements that support no higher layer protocols beyond the MAC sub-layer.

FDDI MAC services design considerations

Abstract: The FDDI MAC (media access control) standard outlines a set of services that are to be made available to other entities, such as logical link control (LLC) and station management (SMT). The number of services and the method by which MAC provides these services using the standard FDDI facilities and operation are not specified, however, and are implementation-dependent. The author addresses some of the considerations that arise when choosing the appropriate set of services for the media access control (MAC) sublayer of an FDDI station, whether one is designing or purchasing these MAC functions. >

VLSI architecture for IEEE 802.5 token-ring LAN controller

Abstract: A description is given of the architecture of the token-ring LAN controller (TRC) compatible with IEEE 802.5 media access control (MAC) protocol, which integrates a frame transmit/receive hardware, a high-speed protocol processor, a three-channel DMA controller (DMAC) and large-capacity dual-port RAMs. The performance analysis of the frame transmit/receive shows that the TRC is suitable not only for small computers, but also for high-performance applications

Random access systems: ALOHA's progeny

Abstract: Random access algorithms allow a large number of bursty data sources to share a common transmission medium. Such algorithms are essentially refinements of the distributed algorithm first introduced in the ALOHA system. Unlike techniques such as time division multiple access (TDMA), frequency division multiple access (FDMA) and polling, the performance of random access algorithms is insensitive to the number of stations in the system. The weakness of early random access systems is extreme sensitivity to traffic, resulting in instability. Later implementations of the technique have improved throughput, eliminating instability. This paper discusses the three forms of random access techniques: stable backoff algorithms, tree search algorithms and carrier sensing techniques. Forms of the last of these have been used in an optical-fibre local area network. The particular application of random access techniques to satellite communication systems is also considered.

The Impact of Security Service Selection for LANs

Abstract: IEEE 802 has defined a Local Area Network (LAN) architecture that contains a Logical Link Control (LLC) and a Media Access Control (MAC) protocol layer. Within this architecture, IEEE 802.10 is attempting to define protocols and interfaces that provide security. The authors of this paper submitted a protocol that implemented a specific set of security services and was placed between the LLC and MAC layers. This paper explains why the placement between the two layers was preferred to the placement being above LLC or within the LLC or MAC layers. It describes the security services that can be obtained by different placements, but then describes the reasons that between the MAC and the LLC was deemed the best option.

Integrated MANs with hierarchical architecture

Abstract: A description is given of metropolitan area networks (MANs) for integrated services that consist of local clusters connected through bridges to a backbone network. The services integration as well as the required flow control functions are obtained with simple procedures which operate at the media access control (MAC) level. The effectiveness of this hierarchical architecture is evaluated in the case where the local clusters and the backbone network are implemented using L-express buses. The efficiency of this architecture is compared with that of other alternatives and detailed performance results in saturation condition, obtained with simulations, are presented. >

Modeling and performance evaluation of MAC layer of FDDI

Abstract: This paper presents a computer simulation of the Media Access Control sublayer of the Fiber Distributed Data Interface. FDDI is a proposed ANSI standard for a high-speed optical token ring computer network. FDDI's MAC layer is reviewed, the modeling environment is presented, and the simulation results are discussed.

Packet protocol communication device

Abstract: PURPOSE:To easily switch systems when a packet protocol converter becomes detective by providing a multi-address communication means which delivers and receives call controlling packets between terminal equipment and plural packet protocol converters after putting the call controlling packets on frames of a multi-address fram in addition to a route connecting means. CONSTITUTION:This packet protocol communication device is constituted in such a way that a multi-address frame transmitting section 8 and multi-address frame receiving sections 9 are respectively provided to terminal equipment 3 connected with an LAN 2 and the packet protocol converters 4, and MAC (Media Access Control) frames of a multi-address form are used for CR(Call Request) packets which are partner connection controlling originating call (call controlling) packets for connecting communication partners. When the MAC frames of s multi-address form are adapted to the CR packets in such way, connection switching to the packet protocol converters 4 of a double-system constitution can be realized extremely easily with a simple constitution.

FDDI and BWN backbone networks: a performance comparison based on simulation

Abstract: An analysis is conducted of two multiple-token-ring protocols serving as backbone networks, namely the fiber distributed data interface (FDDI) and the backbone wideband network (BWN) developed in the framework of an European research project (ESPIRIT 73). The traffic on the local area network comprises file transfer as well as interactive traffic. The performance of both media-access-control strategies is evaluated with respect to buffer space requirements and packet/file delays, and the sensitivity of the FDDI protocol is studied for several target token rotation times. Both protocols are shown to work very well for typical numbers of stations ( >

Fast Ring: a distributed architecture and protocol for local area distributed processing

Abstract: A ring-based media access control protocol and architecture, Fast Ring, which combines the best features of the token ring and contention ring, is proposed. For this protocol, a free token circulates on the ring when the ring is idle. A ready station can transmit either by capturing the token or sensing the ring idle. The protocol works in such a way that the ready node which captures the free token, before or while transmitting, is able to continue transmission. All the other contending nodes have to stop their transmissions and then send the abort signal when they receive the upstream transmission. After its transmission, the successful station puts a free token on the ring and the protocol enters the token mode. It behaves like the token ring protocol until the ring becomes idle again when all the ready nodes complete their transmissions. Comparison of the performance of Fast Ring with those of contention ring, token ring, and carrier-sense multiaccess with collision detection protocols shows that the Fast Ring outperforms all these local area network protocols over the whole throughput range at all transmission rates. >

Modeling and performance evaluation of FDDI ring

Abstract: A computer characterization of the fiber distributed data interface (FDDI) is presented The FDDI's first three sublayers, physical medium dependent (PMD), physical layer protocol (PHY), and media access control (MAC), are reviewed and simulated Simulations for each sublayer are performed individually, and results from lower sublayers are incorporated at higher levels Results are presented and discussed >

Applying the SRPT Principle to Improve the Performance of the CSMA/CD Media Access Control Protocol

Abstract: The optimal preemptive strategy SRPT1 reduces the mean delay time by preferring short jobs or messages especially in systems with a high coefficient of variation of the message length. In packet switching networks the service time, i.e. the transmission time, is known in advance, so that this strategy can be applied. The CSMA/CD2 media access control (MAC) protocol of the widely used Ethernet LAN’s with their heterogeneous mixed traffic load is a promising object for a first application of SRPT. In this paper the optimized CSMA/CD/SRPT protocol based on this strategy is introduced. Access to the channel is allowed only to messages which are shorter than the rest of the message currently transmitted. Short messages can interrupt the transmission of a longer one by provoking a collision. After such a collision stations start their transmission according to the message length in reserved slots. This is similar to the hyperchannel priorities for station numbers. Simulation results for a realistic network topology and user scenario show that the mean transfer time of interactive terminal traffic and paging traffic as well as that of the total traffic can be substantially reduced.

Access Control and Authentication in LANs

Abstract: This paper explores the uses for security mechanisms confined to OSI layer 2, even in LANs that also employ wide area protocols up through layer 7. These mechanisms must be integrated into the protocol architecture in a way that will not interfere with or be redundant to very similar security mechanism implemented in higher layers operating across the wide area network. A model for such mechanisms in the context of IEEE 802 LANs is proposed.

A study of priority at the transport layer in local area networks

Abstract: In the computer integrated manufacturing (CIM) environment and other integrated services types of networks, short time critical messages share network resources with bulk data transfer, creating the need for priority schemes. The OSI (open systems interconnection) reference model defines priority to be primarily a part of the functionality of the medium access control sublayer of the data link layer. Results from a simulation study that establish the need for an additional priority scheme at the transport layer over and above the existing scheme at the MAC (medium access control) layer are presented. >