A simulation of fiber distributed data interface for token ring lan protocols

The survivable adaptable fiber optic embedded network (SAFENET) program, an effort by the US Navy to develop standard computer network profiles that meet the requirements of navy shipboard mission-critical computer systems, is discussed. The two SAFENET standards currently in development are described. The distinction between them is restricted to the commercial local area network (LAN) upon which each is based. SAFENET I uses the IEEE 802.5 token ring LAN, which operates at 16 Mb/s. SAFENET II uses the fiber distributed data interface (FDDI) LAN, which operates at 100 Mb/s. The SAFENET transmission system, optical power budget, and application methodology are examined. >

It is well known that Fiber Distributed Data Interface (FDDI) offers an excellent cost-benefit and guarantees a reliable and powerful network. It is also fact that the FDDI is suitable for synchronous traffic because of the high speed and the performance guarantees it provides. However, these guarantees are achieved at the expense of asynchronous traffic because the synchronous messages are given highest priority over asynchronous messages, resulting in excessive delays and low throughput for asynchronous message. This paper, presents a modification of the FDDI's MAC(Media Access Control) protocol to control the maximum token rotation time not to exceed the TTRT (Target Token Rotation Time) in the worst case, the realization of this condition leads to set the TTRT to the message generation period (Tg) instead of one half of it (Tg/2). The new protocol of FDDI’s MAC increasing both the throughput of asynchronous traffic and the capacity of synchronous sources. The proposed MAC is evaluated by means of computer simulation. The simulation results confirm that the new proposed MAC provides FDDI more efficient for supporting multimedia applications.

FDDI-2 is an extension of the fiber distributed data interface (FDDI) standards that integrates isochronous circuit switched services with the timed token protocol packet services of FDDI. An expression is derived to describe the effects of hybrid mode operation on the packet channel token rotation time, which is dependent on the maximum isochronous transmission rate. The management of packet data in several possible latency adjustment buffer (LAB) implementations during steady state and programming template changes is described. One basic choice is to operate the LAB as a strict FIFO, keeping a fixed network delay, and another performs more efficient delay management by bypassing the isochronous delay when possible. LAB operation and programming template changes greatly affect the operation of the packet channel. Both affect the range of the token rotation time that is used in the packet channel.

Performance issues of the FDDI-II protocol, an upward-compatible enhancement of the basic fiber distributed data interface (FDDI), are discussed. The main characteristics of the FDDI protocol are examined. The performance of FDDI-II is studied for scenarios including asynchronous traffic, synchronous traffic and isochronous traffic. The results make clear that basic FDDI meets the requirements imposed by traditional local area network (LAN) application and that from a performance point of view FDDI-II is an excellent candidate for complex communications environments. When compared to the distributed-queue-dual bus (DQDB) protocol, FDDI-II yields much better efficiency in traditional LAN applications. >

The problem of fast filtering in bridging Ethernet local-area-networks (LANs) through high speed fiber distributed data interface (FDDI) networks is addressed. A filtering algorithm, called MFA is introduced, which sets the minimum power requirements for a bridge connecting an Ethernet LAN to an FDDI backbone. A hardware solution based on the use of content addressable memories is described. The MFA tries to avoid packet broadcasting on the FDDI ring. This is done by keeping track of remote Ethernet addresses coupled with the FDDI address of the related bridge. With MFA, the bridge performs filtering and routing operations only on packets coming from the Ethernet side, while the filtering from FDDI side is directly performed by the FDDI media access control. As a result, MFA has only to cope with the maximum Ethernet transmission rate, slower by one order of magnitude, and thus requiring less processing power. >

This paper studies two methods of interconnecting heterogeneous local area networks (LANs) such as Carrier-Sense Multiple-Access (CSMA) and token ring networks in an open systems environment, and evaluates the associated system performance. The first interconnecting method is to link the two LANs through gateways; the second is to use an architecture in which some stations on the ring LAN are also linked to the CSMA LAN via a multiplexer. Through such interconnected LANs, the Department of Defense end users can process data and applications seamlessly in an open systems environment. It has been shown that the second method (a type of dual interface) gives better performance in minimizing the response time and token rotation time, causing less traffic congestion. By allowing routing at the stations on the ring, the comparison becomes rather arbitrary. An optimal traffic routing ratio is determined for the second interconnection method. Moreover, a threshold routing ratio, beyond which the first interconnection is superior in performance, is computed. >

Different techniques for improving the exploitation of resources in a high-speed local area network (LAN) are assessed. The techniques analyzed are all based on the exploitation of the redundant resources often introduced in the transmission system to increase the network's fault tolerance. The different strategies are defined for a 100-Mb/s token ring LAN. In order to assess the different strategies, the network is modeled using generalized stochastic Petri nets; the model allows evaluation of the increase in throughput and the construction of diagrams relating access delay to throughput. In comparing the different solutions, the fairness among the various users of the network is also considered. The technique of access to independent channels is shown to be excellent as far as available throughput is concerned, but it introduces unfairness in access to the network and requires particularly complex management strategies. The technique of access to correlated channels, on the other hand, has performance levels which are similar to those provided using the other technique. In addition, it exhibits intrinsic fairness in the access mechanism and does not require complex network management. >

Fiber optic local area networking (FOLAN) is rapidly becoming a reality. It has gone from an engineering curiosity to a commercially available product within the last few years thanks to the emerging standards and general acceptance of fiber optics. FOLANs are ideal for high speed data transport. They eliminate ground loop problems; the media does not require shielding and, in general, requires less space and is lighter weight. Fiber optic media has a much higher bandwidth than equivalent wire systems which will allow for future expansion without requiring a cable plant change. The question of what is presently available and how a typical system is implemented will be answered. There are several FOLANs commercially available or under development at this time. Generically most of them fall in one of these categories: token rings, token buses, and continuous sense multiple access/collision detect (CSMA/CD) networks. Perhaps the most well-known token ring is the fiber distributed data interface (FDDI). One implementation of the token bus is the manufacture automated protocol (MAP). The most popular implementation of CSMA/CD is Ethernet. A brief description of each of the protocols, connection schemes, and available hardware used to implement the networks will be given. The FDDI network will be used to illustrate a typical network realization. The last portion of the presentation will discuss what the future has in store for high speed fiber networks. What are some of the emerging technologies? What is SONET, HPPI, and high-speed channel?

In the distributed‐control ring LAN (local area networks), a reconfiguration control is required to cope with the independent asynchronous failure detection in the stations. This paper proposes a wrapback reconfiguration mechanism in the dual‐token ring LAN with a parallel dual structure of distributed‐control token‐ring LAN. Here, the ring is wrapped back automatically by the distributed‐control of the stations when a fault is detected in the communication function in the physical layer or MAC (medium access control) layer. Each station connected by the dual ring determines its operation based only on the state of the two input links. When an abnormality is detected in a link, a failure‐detecting beacon is transmitted and the failure domain is located by the reception priority competition control, where the transmission is stopped by receiving the beacon. The stations adjacent to the failure domain artificially generate a fault in the output link paired to the failure link, so that the station to wrap back the ring at both sides of the failure link‐pair can be located by the same procedure as for the localization of the failure domain. In parallel to the ring wrapback, the active monitor is established, which is needed in the initialization of the ring. Each station discriminates between the current link and standby link, and the ring wrapback by the failure of the standby link is avoided. Applying the international standard (IEEE 802.5) to the token‐ring LAN, the failure recovery time is evaluated. The effectiveness of the proposed reconfiguration mechanism has already been verified by an experiment using the actual equipment.

This paper presents a new control scheme to realize concurrent transmission for multi-users in multimedia communication on token ring local area networks (LANs). When a token arrives-at a station continuously transmitting a frame to another station, the station will insert a control pattern called insertion pattern IP to the data field of the frame. A destination station will detect such a pattern and release a new token to the ring. Thereby, concurrent transmissions between stations can be performed. Simulation results show that the scheme has better performance than that of conventional token rings. >

Asynchronous transfer mode (ATM) networks can support a wide variety of applications with varying data rates. Fiber Distributed Data Interface (FDDI) networks are targeted to support similar applications, but only in a LAN environment. Both of these networks are characterized by high data rates and low error rates. In addition, they can provide applications with varying degrees of performance guarantees. A problem of designing a high-performance gateway architecture for internetworking between these two important classes of networks was addressed in [Kapoor, 1991b]. An important part of the gateway design philosophy was to partition the internet functions into critical and non-critical paths. The critical path consists of per packet processing, an is implemented in hardware. The non-critical path consists of connection, resource, and route management, and is implemented in software. In order to establish the feasibility of this approach to the design of future high-speed gateways, an extensive simulation of the prosed gateway architecture was carried out. The primary focus of this paper is on the description of the simulation model, and its use in characterizing the performance of the proposed gateway architecture.

The Advanced TOMAHAWK Weapons Control System (ATWCS) is being developed to support current and future tactical cruise missiles onboard navy ships. The ATWCS utilizes the Navy's standard Tactical Advanced Computer (TAC) 3 components and commercial standard Local Area Networks (LANs) to provide a flexible, robust system with excellent growth potential. Aggressive use of systems engineering principles has refined the system design so that it is adaptable to various Navy platforms. An excellent example of the success in meeting this design goal is the Submarine ATWCS.The primary data pathway for ATWCS is a Fiber Distributed Data Interface (FDDI) LAN connecting the four TAC 3 processors. Existing Common Display Consoles (CDCs) are used for display and control of the TAC 3 processors. The Submarine ATWCS builds on software already developed for surface ships. The open system architecture of this software is based on Computer Software Configuration Items (CSCIs) and several are obtained from other programs. Direct weapons interface in the Combat Control System (CCS) provides optimum efficiency in weapons control while gaining the functionality advantages of ATWCS.This paper describes the systems engineering solutions for both software and hardware to achieve a modern cruise missile weapons control capability for submarines utilizing non‐development items (NDI). Commercial Off The Shelf (COTS) technology, LANs and open system architecture.

In this paper, we present a performance analysis of how effective video server applications can be supported on personal computers (PCs) connected through a local area network (LAN). We considered both the standard 16-Mbit/s token ring and a 100-Mbit/s token ring, which follows closely the specifications for the Fiber Distributed Data Interface (FDDI). We examined three I/O architectures for a PC-based video server: an interrupt-driven I/O architecture, a peer-to-peer I/O architecture, and a concurrent, object-based I/O architecture that we proposed. The video server must support multiple MPEG-1 video streams at the same time to multiple clients on the LAN. We found that the network protocol layers require a lot of processing power, and that an implementation of our proposed I/O architecture, which takes advantage of the available power of the host processor to off-load I/O adapters, can deliver much better performance, and is more cost-effective, than other I/O architectures in a video server environment.

The author examines two broadly supported ring designs, IEEE 802.5 and the Fiber Distributed Data Interface (FDDI), X3T9.5 currently emerging as local area network (LAN) standards, and explores the basis of this interest in ring topologies. The advantages that ring designs offer are presented, and on this basis a proliferation of rings is envisioned for the next decade.

In modern times, where the speed of transmission is of utmost importance, often need arises for a reliable transmission medium. With innovations in LAN (local area networks) such as FDDI (fiber distributed data interface), fiber optic data links and associated interface schemes are gaining more and more acceptance and actually are becoming real necessities. In this article, the author describes a simple design methodology for a fiber optic data link and presents criteria to evaluate the performance and frequency response properties of these data links. In addition, a simple wavelength division multiplexing (WDM) scheme for improved data rate is also presented.