# Network Topology And Data Link Control Computer Science Essay

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A computer network is made of computers which are linked to one another with communication lines and hardware elements. Network topology is one of the examples of computer networking.

Network topology is called a geometric shape that are distributed work stations and cables that connect. The workstations on a network communicate with each other through a physical connection and the topology of the object is to find the most economical and efficient connectivity. While providing the reliability of the system, to avoid waiting times at data transmission, allowing for better control of the network in an efficient and allow an increased number of computers on the network.

Topology describes the configuration of a communication network. In which the elements of a network map or arrangement is known as a method of network topology. Network topology describes the difference between physical and logical interconnection nodes. It can be divided into physical network topology, logic and signal topology. A physical topology describes the network nodes and their physical connection between the mapping. Topological description of the signal path, in which signal, and they need via the network. The mapping is the data path as information travel on the network known as the logical topology. Terms, the signal topology and logical topology are closely related.

Topology can be considered as a virtual shape or network structure. This shape does not meet the actual physical design of computer network equipment. Computers on a home network can be arranged in a circle, but it does not necessarily mean that it is a ring topology.

Any particular network topology is decided only by the physical nodes and / or logical connection configuration of the graphical map. In the study of network topology graph, the physical interconnection between nodes, transmission rate, and / or signal types may be different from, but the topology of the two networks may be the same.

Local Area Network (LAN) is an example of the network, exhibits both physical topology and logical topology. LAN any given node has one or more links to one or more nodes of the network, and the geometry of links and nodes of a graph may be used to describe the results of the physical network topology map. Similarly, the flow of data between network nodes determines the mapping of the logical topology of the network. Physical and logical topology may or may not be the same in any given network.

Data Link Control is a non-routable protocol used only on computers performing these tasks and is not configured as a primary protocol for use between workstation computers. A device driver for the Data Link Control protocol interface is also included with WindowsÂ 2000.

Data Link Control is the service provided by the data link layer of function defined in the Open System Interconnection (OSI) model for network communication. The Data Link layer is responsible for providing reliable data transfer across one physical link (or telecommunications path) within the network. Some of its primary functions include defining frames, performing error detection or ECC on those frames, and performing flow control.

In local area networks (LANs) where connections are multipoint rather than point-to-point and require more line-sharing management, the Data Link layer is divided into two sub layers: the Logical Link Control layer and the Media Access Control layer. The Logical Link Control layer protocol performs many of the same functions as the point-to-point data link control protocols described above. The Media Access Control (MAC) layer protocols support methods of sharing the line among a number of computers. Among the most widely used MAC protocols are Ethernet, Token Bus, and Token Ring and their derivatives.

Data Link Control is a specialized network protocol that is used primarily for two purposes. First, it is to provide connectivity with IBM mainframe or AS/400 environments, such as System Network Architecture (SNA), which are configured to Data Link Control. Data Link Control complements System Network Architecture because System Network Architecture operates only at higher levels of the OSI model. Besides that, it is providing connectivity for network print devices (such as certain Hewlett Packard printers that have their own network cards and are connected directly to the network).

Data Link Control is not used as a network protocol in the usual sense of enabling communication among computers on the network. It is not used by the redirector in the Microsoft Windows NT and Windows 2000 operating systems and so cannot be used for session-level communication over a network. DLC is not routable; it is designed only to give devices direct access to the data-link layer.

## Define Question 1

Topology can be considered as a virtual shape or network structure. This shape does not meet the actual physical design of computer network equipment. Computers on a home network can be arranged in a circle, but it does not necessarily mean that it is a ring topology.

Interconnected network topology is the layout of the various elements of the computer network (links, nodes, etc.). Network topology may be physical or logical. Is a physical topology, including equipment, installation location and physical design of the cable network. Logical topology is how the data is actually transmitted over a network, rather than its physical design.

A network consists of multiple computers connected using some type of interface, each having one or more interface devices such as a Network Interface Card (NIC) and/or a serial device for PPP networking. Each computer is supported by network software that provides the server or client functionality. The hardware used to transmit data across the network is called the media. It may include copper cable, fiber optic, or wireless transmission. The standard cabling used for the purposes of this document is 10Base-T category 5 Ethernet cable. This is twisted copper cabling which appears at the surface to look similar to TV coaxial cable.

Network topology refers to the way in which the network of computer is connected. Each topology is suited to specific tasks and has its own advantages and disadvantages. The communications traffic on the Internet backbone is exchanged at large Internet Exchange Points (IXP), sometimes called Network Access Points (NAP) or Metropolitan Area Exchanges (MAE), constituting the top level of the Internet network topology.

Any particular network topology is decided only by the physical nodes and / or logical connection configuration of the graphical map. In the study of network topology graph, the physical interconnection between nodes, transmission rate, and / or signal types may be different from, but the topology of the two networks may be the same. Local Area Network (LAN) is an example of the network, exhibits both physical topology and logical topology.Local area network is one of the connector. Its maximum segment length is 100 meters. In Network Topology, there are several types of topology. Letââ‚¬â„¢s see the different types of network topologies in detail.

## Top of Form

Bus topology: In this type of network topology, all network nodes connected to a common transmission medium has two endpoints. All data transmitted over the network through a common transmission, the backbone of the bus or network-known media. When the transmission medium has exactly two endpoints, the network topology is known the name of the 'linear bus topology. In the case of the transmission medium, also known as the backbone of the network, with more than two endpoints, the network is said to have a distributed bus topology. Bus topology is easy to handle and implement, is ideal for small networks. However, the shortcomings of this topology are that the limited cable lengths limit number of stations, limiting the performance to a small number of nodes.

Ring topology: In a ring topology, each node in the network connections to other nodes, and two of the first and last node is connected to each other. And the transmission, each node in the network by passing data until the ring reaches the destination node. In a ring network, data and signals, in the past the network pass in one direction. Double ring topology changes between nodes in a network each of the two connections. In the two rings along the two directions of data flow, and thus formed. Ring topology does not require a central server to manage connections between nodes and network operations to facilitate an orderly manner. However, a single station of a network failure can paralyze the entire network. Change and form a network of stations in the mobile network operations.

Mesh topology: In a fully meshed network, each network node connected to each other nodes in the network. Because of this node arrangement may be a signal transmitted from one node to several other nodes. In the part of the mesh network connectivity, only a few network nodes connected to multiple nodes. This is all nodes in a point-to-point link between the redundancy caused by favorable conditions for fully connected mesh. A mesh network routing node needs to have some logic, so that the signal and data transmission across the network to take the shortest path for each.

Star topology: In this type of network topology, each network node is connected to a central node, which is known as a center. That the transmission of data between network nodes through the central hub. Distributed Star is the star of two or more separate network interconnection. The nature of the star provides a centralized network of a certain amount of simplicity, but it also achieves the network on each devise isolated. However, the disadvantage of star topology is the network transmission is heavily dependent on the central hub.

Tree topology: it is also known as hierarchical topology, with a central root node is connected to one or more of the low-level nodes. In a symmetric hierarchy, the network each node has a connection at a lower level of the specific number of years these nodes.

Hybrid topology: This is a combination of any two or more network topologies. Hybrid topology can occur where two basic network topologies, when connected together, can still retain the basic network character, and therefore not be a hybrid network. For example, a tree network connected to a tree network is still a tree network. Therefore, a hybrid network accrues only when two basic networks are connected and the resulting network topology fails to meet one of the basic topology definitions. For example, two star networks connected together exhibit hybrid network topologies. A hybrid topology always accrues when two different basic network topologies are connected.

## Define Question 2

Data link control is the development of network communication systems interconnection model defined in the data link layer services. Data link layer is responsible for providing the data within the network across an actual link (or communication path) of the reliable transmission. Some of its basic functions include: the definition of the frame, the frame to perform error detection or ECC, the implementation of flow control (to prevent fast senders to slow receiver that a lot of information.)

In Data Link Control, data link layer might be important in data link control. Data link layer algorithms may be embedded in the network hardware. Itââ‚¬â„¢s rather than running as software process on a machine. Generally, computer algorithms don't have to be run as software on general-purpose machines. User can design dedicated hardware to run them. Usually that hardware is increasing speed for fundamental algorithms run constantly or some combination of dedicated hardware plus limited-programmable.

Data link layer is the source of the most basic services to the computer network layer reliable transmission of data to adjacent nodes in the network layer of the target computer. To that end, the data link layer must have a corresponding function, are: how the data is combined into data blocks (in the data link layer data block will be referred to this frame, the frame is the data link layer transmission unit); how to control the transmission of frames in the physical channel, including how to deal with transmission error, how to adjust the sending rate in order to make and receiving way match; in between two network entities established to provide data link paths, maintenance and release management.

Between two devices, the real exchange digital data, the need to use some form of data link control. This is due to the possibility of transmission errors; and the data receiver is sometimes necessary to adjust the data arrival rate, or may handle the received data leaving no time to receive buffer overflow. Therefore, synchronization, and interface technology alone is not enough. Investigated here, all the common data link control protocol flow control, error detection and correction, and link (line) procedures and other infrastructure technologies, and describes the most commonly used protocol HDLC.

To achieve based on two-point data link connected directly to the high efficiency of the purpose of data communications, data link control functions include frame synchronization, flow control, error control, addressing, control information and data combined link, link management.

Flow control determines the sender once the amount of data that the receiver can only adjust the flow of data from sender to prevent receiver buffer overflow. Transfer model based on the frame, such as the use of stop and wait flow control, should avoid sending the data frame or the loss of its acknowledgment frame to be trapped in an infinite wait. Sliding window flow control can be applied to an occasion to send multiple frames. Line utilization is the main factor to consider flow control.

Error detection relies on the calculation of error detection code implementation; the code is transmitted as a function of the bit group. Linear block code, the sender will transmit error detection code attached to the back of the bit group; receiver group according to the received bit error detection codes are calculated, and then receive the error detection code and compare to check wrong.

Error control means is used to detect and correct errors in the transmission mechanism. It might be loss or damage to both the frame error types. The most commonly used error control techniques are based on all or part of the following mechanisms: error detection, positive acknowledgment after the retransmission timeout, retransmission denied. The combination of these mechanisms has become stop and wait ARQ, step back N ARQ, choose to reject ARQ three standard ARQ (Automatic repeat request error control techniques). There are other error control techniques FEC (forward error correction) and HEC (mixing error correction) and so on. By the way that single-bit error, burst error and other error categories.

## Conclusion & Recommendation

In Question 1, most suitable network topologies for business are bus topology, ring topology, tree topology and hybrid topology. In my opinion, the bus topology are better use for all worker, it is because all worker can share one line by using bus topology. For the ring topology, it is suitable for some worker and manager. They can use ring topology to transfer their information directly though the top manager. For those customer can use the line with tree topology and hybrid topology, so that they can share or transferring data and all information can be control by the business company.