Comparison of Network Topologies for Optical Fiber Communication

International Journal of Engineering Research & Technology (IJERT) ISSN: 2278-0181 Vol. 1 Issue 10, December- 2012

Comparison Of Network Topologies For Optical Fiber Communication

Mr. Bhupesh Bhatia Ms. Ashima Bhatnagar Bhatia Department of Electronics and Communication, Department of Computer Science,

Guru Prem Sukh Memorial College of Engineering, Tecnia Institute of Advanced Studies, Delhi Delhi Ms. Rashmi Ishrawat Department of Computer Science,

Tecnia Institute of Advanced Studies, Delhi

Abstract advent of the Information age. Optical In this paper, the various network topologies technologies can cost effectively meet have been compared. The signal is analyzed as it corporate bandwidth needs today and passes through each node in each of the network tomorrow. Internet connections offering topology. There is no appreciable signal degradation in the ring network. Also there is bandwidth on demand, to fiber on the increase in Quality factor i.e. signal keeps on LAN. Fiber to the home can provide true improving as it passes through the successiveIJERT IJERTbroadband connectivity for nodes. For the bus topology, the quality of signal telecommuters as well as converged goes on decreasing with increase in the number multimedia offerings for consumers [2]. of nodes and the power penalty goes on increasing. For the star topology, it is observed These different communication networks that received power values of each node at a can be configured in a number of same distance from the hub are same and the topologies. These include a bus, with or performance is same. For the tree topology, it is without a backbone, a star network, a observed that the performance is almost identical ring network, which can be redundant to the performance of ring topology, as signal quality is improved as it passes through the and/ or self-healing, or some successive nodes of the hierarchy. combination of these. Network topology is the study of the arrangement or I. Introduction mapping of the elements (links, nodes, Communication systems have etc.) of a network, especially the revolutionized the telecommunications physical (real) and logical (virtual) industry and played a major role in the interconnections between nodes A local

www.ijert.org 1 International Journal of Engineering Research & Technology (IJERT) ISSN: 2278-0181 Vol. 1 Issue 10, December- 2012 area network (LAN) is one example of a received by all nodes in the network network that exhibits both a physical and virtually simultaneously. Star is the a logical topology. Any given node in topology in which each of the nodes of the LAN will have one or more links to the network is connected to a central one or more other nodes in the network node with a point-to- point link. All data and the mapping of these links and that is transmitted between nodes in the nodes onto a graph results in a network is transmitted to this central geometrical shape that determines the node, which is usually some type of physical topology of the network [1]. device that then retransmits the data to some or all of the other nodes in the network, although the central node may also be a simple common connection point without any active device to repeat the signals. In ring topology, each of the nodes of the network is connected to two other nodes in the network and with the first and last nodes being connected to IJERTIJERTeach other, forming a ring. All data that is transmitted between nodes in the network travels from one node to the next node in a circular manner and the Fig. 1. Diagram of different network topologies. data generally flows in a single direction Fig. 1 shows the different types of only. In tree topology, the central ‘root’ topologies. Bus is the network topology node (the top level of the hierarchy) is in which all of the nodes of the network connected to one or more other nodes are connected to a common transmission that are one level lower in the hierarchy medium which has exactly two (i.e. the second level) with a point-to- endpoints (this is the ‘bus’, which is also point link between each of the second commonly referred to as the backbone, level nodes and the top level central or trunk) – all data that is transmitted ‘root’ node, while each of the second between nodes in the network is level nodes that are connected to the top transmitted over this common level central ‘root’ node will also have transmission medium and is able to be

www.ijert.org 2 International Journal of Engineering Research & Technology (IJERT) ISSN: 2278-0181 Vol. 1 Issue 10, December- 2012 one or more other nodes that are one clients are connected via a shared level lower in the hierarchy. communications line, called a bus. This Optical networks are the next revolution topology is easy to implement and in technology, because they deliver the install. It is well-suited for temporary or increased bandwidth demanded by the small networks not requiring high speeds information explosion. Optical networks (quick setup), resulting in faster are spreading outward from Internet networks. Cost effective and easy backbones to cities to corporations and identification of cable faults is possible. even to the home. Cities are in a Moreover, Bus networks are the simplest strategic position to create a leading- way to connect multiple clients, but edge optical infrastructure that will drive often have problems when two clients economic growth [3]. Optical want to transmit at the same time on the technologies can cost-effectively meet same bus. Thus systems which use bus corporate bandwidth needs today and network architectures normally have tomorrow. Internet connections offering some scheme of collision handling or bandwidth on demand, to fiber on the collision avoidance for communication LAN. Fiber to the home can provide true on the bus, quite often using Carrier broadband connectivity forIJERT IJERTSense Multiple Access or the presence of telecommuters as well as converged a bus master which controls access to the multimedia offerings for consumers [2]. shared bus resource. Many active Based on optical fiber cables, digital architectures can also be described as a microwave and satellite subsidiary, a ‘‘bus’’, as they provide the same logical transport network with fully coverage, functions as a passive bus, for example, large capacity and high rate has been switched Ethernet can still be regarded basically formed. However, the as a logical bus network, if not a development of the transport network is physical one. The limitations of Bus still slower as more and more capacity is Network topology are limited fiber needed for various communication length, higher Maintenance costs, if technologies. there is a problem with the cable, the entire network breaks down. Moreover, II. Bus network topology: the performance degrades as additional computers are added or on heavy traffic A bus network topology (fig. 2) is a (shared bandwidth). network architecture in which a set of www.ijert.org 3 International Journal of Engineering Research & Technology (IJERT) ISSN: 2278-0181 Vol. 1 Issue 10, December- 2012

all links between devices. To implement a ring network, one typically uses FDDI, SONET, or Token Ring technology. Ring topologies are found in some office buildings or school campuses.

Fig. 2. Bus network layout

Fig. 3. Ring network layout III. Ring network Topology

IV. Star network topology In a ring network (fig.3) each node connects to exactly two other nodes, Star networks are simplest form of forming a single continuous pathway the network topologies. This network for signals through each node - a topology consists of one central ring. Data travels from node to node,IJERT computer, which acts as a central with each node along the way IJERTnode, to which all other nodes are handling every packet. Ring network connected. This central node Performs better than a bus topology provides a common connection point under heavy network load and does for all nodes through a hub. If the not require a central node to manage central node is passive, the the connectivity between the originating node must be able to computers. But the limitations are tolerate the reception of an echo of that one malfunctioning workstation its own transmission, delayed by the can create problems for the entire two-way transmission time (i.e. to network or a node failure or cable and from the central node) plus any break might isolate every node delay generated in the central node. attached to the ring. Communication An active star network(fig. 4) has an delay is directly proportional to active central node that usually has number of nodes in the network. In the means to prevent echo-related adition, bandwidth is also shared on problems. The star topology reduces

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the chance of network failure by all peripheral nodes on the network, connecting all of the systems to a sometimes including the originating central node. When applied to a bus- node. All peripheral nodes may thus based network, this central hub communicate with all others by rebroadcasts all transmissions transmitting to, and receiving from, received from any peripheral node to the central node only. The failure of transmission line linking any peripheral network, a cable failure in one of the star node to the central node will result in the networks will isolate the node that it isolation of that peripheral node from all links to the central node of that star others, but the rest of the systems will be network, but only that node will be unaffected. isolated. The limitations of the tree topology are If the backbone line breaks, the entire segment goes down and it is more difficult to configure and wire than other topologies.

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Fig. 4. Star network layout.

V. Tree network topology

A tree topology combines characteristics of linear bus and star topologies. It consists of groups of star-configured workstations connected to a linear bus Fig. 5. Tree topology layout backbone cable (fig. 5). Tree topologies allow for the expansion of an existing VI. Conclusion network, and enable schools to configure In this paper, the various network a network to meet their needs. It is easy topologies comprising of various nodes to add or remove nodes from each star have been compared. For bus network network as there is Point-to-point wiring topology, the quality of signal goes on for individual segments. In a tree decreasing with decrease in signal input www.ijert.org 5 International Journal of Engineering Research & Technology (IJERT) ISSN: 2278-0181 Vol. 1 Issue 10, December- 2012 power and the power penalty goes on Using optical fiber various topologies increasing. It is also observed that power came into being. Each topology has its received goes on increasing with strengths and weaknesses, and some increase in input power. The main network types work better for one limitation of bus topology is its limited application while another application cable length and number of stations. If would use a different network type. there is a problem with the cable, the References: entire network goes down. Maintenance costs may be higher. In Ring network [1] G.P. Agarwal, Applications of Nonlinear topology, the quality of signal keeps on Fiber Optics, Academic Press, SanDiego, CA, improving as it passes through the the 2001. successive nodes. In a simple ring, [2] G.P. Agrawal, Optical Communication Systems, Wiley, New York,1992. break in the ring can disable the entire [3] E. Zouganeli, Migration to optical network. Unidirectional traffic can be a networking, in: Proceedings of International disadvantage in the ring network. The Conference on Transparent Optical Networks, star topology reduces the Chance of vol. 1, Nottingham, June 2006, pp. 98–101. network failure by connecting all of the

Systems to a central node. The failure ofIJERT IJERT a transmission line linking any peripheral node to the central node will result in the isolation of that peripheral node from all others, but the rest of the systems will be unaffected. Although more cabling is required in a star network than in some other topologies. The tree topology can support more number of users by increasing the signal input power. However, it is more difficult to configure and wire than other topologies. Finally we conclude that optical fiber better accommodates today’s increasingly complex network architectures than copper alternatives.