Jagan P. Agrawal

A dynamic high speed multi-media local area network (MLAN) protocol architecture

The design of a multimedia LAN (MLAN) protocol using a broadcast bus system topology suitable for a campus environment is considered. It minimizes the bus access time by using an advanced reservation technique, and accommodates requests for several packet sizes expressed in multiples of asynchronous transfer mode (ATM) cell size. The architecture presented assumes a MLAN speed of 50 Mb/s, and can be easily extended to the STS-3 signal bit rate of 150 Mb/s. The bus access techniques, bandwidth allocation for various types of traffic, clock synchronization, etc. are monitored and changed/adjusted dynamically according to traffic conditions on the bus.<<ETX>>

Supporting connection-oriented service in MLAN protocol

With the emerging ATM broadband networks, there will be a need for connectivity between LANs and broadband networks. The possibility of seamless internetworking between these networks has generated a significant research interest in providing connection-oriented service over LANs. Also, the multimedia nature of traffic is likely to necessitate a connection-oriented service for communication among the LAN terminals as well as between a LAN terminal and non-LAN terminals on ATM networks. We present a technique to provide connection-oriented service on LANs employing a bandwidth reservation scheme. Then we show how this technique is incorporated into a multimedia LAN (MLAN) protocol to provide connection-oriented service. The performance of the protocol under connection-oriented service is evaluated and the results are presented.

Introducing connection-oriented service in MLAN to provide seamless interface to ATM networks

ATM being a connection-oriented technology, there will be a need for connection-oriented service on LANs to be able to provide seamless internetworking between LANs and ATM broadband networks. We present a general technique to provide connection-oriented service on LANs and then show how this technique is incorporated into a recently designed multimedia LAN (MLAN) protocol. The results are presented of a performance evaluation of the MLAN protocol with connection-oriented service.<<ETX>>

A j-bit bus architecture for multimedia local ATM network (MLAN)

With the emerging multimedia services, there is a need to support these services in the local area environment. In the last few years, many LAN protocols have been proposed or modified to fulfill this need. One such protocol is multimedia local ATM network (MLAN) protocol that is based on the bidirectional broadcast bus topology. The MLAN, suitable for campus environment, operates in the native ATM mode and does dynamic and fair bandwidth allocation to service multimedia traffic, and, offers connectionless as well as connection oriented service for MLAN-ATM network communication. From the previously published performance results, it is clear that MLAN provides excellent performance for distances from 1 to 3 km. To support applications requiring longer distances, we propose a new j-bit bus architecture for MLAN protocol. In this architecture, a terminal does not require j separate interfaces but is attached to the j-bit bus using one parallel interface. With the j-bit bus architecture, the MLAN can be extended to many times of the original coverage, depending upon the value of j employed. The MLAN protocols performance has been determined by computer simulation using a multimedia traffic model. Based on the results, the proposed j-bit bus MLAN architecture is well suited for designing high speed multimedia ATM LANs.

Architecture of PLAN: a pipelined-access local ATM network protocol for multimedia applications

This paper presents a shared media ATM LAN architecture known as PLAN (pipelined-access local ATM network) suitable for both LAN and MAN applications. The protocol has been designed for a bidirectional broadcast bus system topology. Stations can be connected at regularly spaced connection points along the bus. This segmentation allows to reduce the bus propagation delay between two successive transmissions to as little as the propagation delay of one segment. This feature helps to effectively reduce the overhead due to bus propagation delay and keep it fixed irrespective of the offered load. The protocol supports tree topology at the cost of slight increase in overhead. The protocol operates in two consecutive phases: one reservation and the other transmission. Although DQDB also limits the propagation delay overhead, the protocol requires the use of 2 buses. Moreover, 2 interfaces per station are required, tree topology networks are not supported, real time traffic is not supported, and an AAL is required to interface with ATM networks. The MLAN protocol addresses most of these problems but suffers from performance deterioration as the number of stations and bus length is increased-hence it is not suitable for the MAN environment. The proposed PLAN protocol (i) operates in the native ATM mode, (ii) guarantees continuous access to real-time traffic and high priority data traffic, (iii) achieves throughput approaching 100% for a 200 station LAN of 1 km length operating at 150 Mbps. The throughput decreases by a fraction of a percent for each kilometer increase in bus length. Based on these and other results, the proposed broadcast bus system PLAN architecture is seen to be well suited for high speed multimedia ATM LAN and MAN applications.

A Distributed Binary Tree Protocol with Advanced Reservation (DBTP/AR) for Local Area Networks

When several different types of services such as data, speech, video, facsirmile, etc., are integrated into a local area network (LAN) and/or when traffic is quite high, a multipacket-user environment is created. In this paper, we propose and evaluate a new protocol called Distributed Binary Tree Protocol with Advanced Reservation (DBTP/AR) where a terminal with multiple packets is allowed to make advanced reservation in the next transmission cycle thereby reducing the number of collisions. The performance of DBTP/AR has been compared with that of the conventional Distributed Binary Tree Protocol (DBTP). Mean throughput and mean packet delay performances of both DBTP/AR and DBTP protocols have been determined by computer simulation with channel bit rate, packet length, and packet arrival rate as parameters. From the results it is seen that the throughput under moderate to high traffic conditions approaches to 1 packet/slot in the case of DBTP/AR compared to 0.5 packet/slot for DBTP, depending upon the above parameters. For example at a bit rate of 3 Mbps and a packet size of 24 bits the maximum throughput for DBTP/AR protocol was found to be about 49% with a mean packet delay of 42 ms while those for DBTP protocol were found to be 25% and 120 ms, respectively. Based on the results it is seen that the DBTP/AR protocol is well suited for designing a high throughput and low mean packet delay local area network for operation in a normal as well as integrated services environments.