Chapter 11

I am somehow informed about the issues to be considered when connecting and configuring computers, switches, and routers to build an Ethernet-based local area network. The chapter also presentd the Cisco Internetwork Operating System (IOS) software and the configuration files for routers and switches. Accessing and using the IOS CLI modes andconfiguration processes, and understanding the significance of the prompt and help functions were also included. I also learned that the planning and designing are important proccesses to consider for the contribution for the successful installation of an operating network.Managing IOS configuration files and using a methodical structured approach to testing and documenting network connectivity are key network administrator and network technician skills.The various LAN and WAN media types and their associated cables and connectors were considered so that the most appropriate interconnection decisions can be made.Determining the number of hosts and subnets in a network required now - and simultaneously planning for future growth - ensures that data communications are available at the best combination of cost and performance.Similarly, a planned and consistently implemented addressing scheme is an important factor in ensuring that networks work well with provisions to scale as needed. Such addressing schemes also facilitate easy configuration and troubleshooting.The IOS operational details vary on different internetworking devices, depending on the device's purpose and feature set.The services provided by the Cisco IOS are generally accessed using a command line interface (CLI). The features accessible via the CLI vary based on the version of the IOS and the type of device.There are several ways to access the CLI environment. The most usual methods are: Console, Telnet or SSH, AUX port, Console.The CLI can be accessed through a console session, also known as the CTY line. A console uses a low speed serial connection to directly connect a computer or terminal to the console port on the router or switch. The console port is a management port that provides out-of-band access to a router. The console port is accessible even if no networking services have been configured on the device. The console port is often used to access a device when the networking services have not been started or have failed.Examples of console use are, the initial configuration of the network device, disaster recovery procedures andtroubleshooting where remote access is not possible, password recovery procedures.The hostname is used in CLI prompts. If the hostname is not explicitly configured, a router uses the factory-assigned default hostname "Router." A switch has a factory-assigned default hostname, "Switch." Imagine if an internetwork had several routers that were all named with the default name "Router." This would create considerable confusion during network configuration and maintenance.

When accessing a remote device using Telnet or SSH, it is important to have confirmation that an attachment has been made to the proper device. If all devices were left with their default names, we could not identify that the proper device is connected. By choosing and documenting names wisely, it is easier to remember, discuss, and identify network devices. To name devices in a consistent and useful way requires the establishment of a naming convention that spans the company or, at least, the location. It is a good practice to create the naming convention at the same time as the addressing scheme to allow for continuity within the organization. The hostnames used in the device IOS preserve capitalization and lower case characters. Therefore, it allows you to capitalize a name as you ordinarily would. This contrasts with most Internet naming schemes, where uppercase and lowercase characters are treated identically. RFC 1178 provides some of the rules that can be used as a reference for device naming. Throughout this chapter, we have discussed commands that are generic to IOS devices. Some configurations are specific to a type of device. One such configuration is the configuration of interfaces on a router. Most intermediary network devices have an IP address for the purpose of device management. Some devices, such as switches and wireless access points, can operate without having an IP address.Because the purpose of a router is to interconnect different networks, each interface on a router has its own unique IPv4 address. The address assigned to each interface exists in a separate network devoted to the interconnection of routers. There are many parameters that can be configured on router interfaces. We will discuss the most basic interface commands, which are summarized in the figure.Router Ethernet interfaces are used as the gateways for the end devices on the LANs directly connected to the router.Each Ethernet interface must have an IP address and subnet mask to route IP packets. To configure an Ethernet interface follow these steps:enter global configuration mode,enter interface configuration mode,specify the interface address and subnet mask,enable the interface. One of the most effective tools for monitoring and troubleshooting network performance is to establish a network baseline. A baseline is a process for studying the network at regular intervals to ensure that the network is working as designed. It is more than a single report detailing the health of the network at a certain point in time. Creating an effective network performance baseline is accomplished over a period of time. Measuring performance at varying times and loads will assist in creating a better picture of overall network performance.The Cisco Internetwork Operating System (IOS) software and the configuration files for routers and switches were presented. This included accessing and using the IOS CLI modes and configuration processes, and understanding the significance of the prompt and help functions.Managing IOS configuration files and using a methodical structured approach to testing and documenting network connectivity are key network administrator and network technician skills.

Chapter 10 Planning and Cabling Network

        I learned that before we can form a functioning network we must connect end devices and intermediary devices via cable or wireless connection.It is this network that will support our communication in the human network. Choosing the appropriate

device is a big thing to consider in froming functioning network.Routers are the primary devices used to interconnect networks. Each port on a router connects to a different network and routes packets between the networks. Routers have the ability to break up broadcast domains and collision domains.outers are also used to interconnect networks that use different technologies. They can have both LAN and WAN interfaces.

The router's LAN interfaces allow routers to connect to the LAN media. This is usually UTP cabling, but modules can be added for using fiber-optics. Depending on the series or model of router, there can be multiple interface types for connection of LAN and WAN cabling. To create a LAN, we need to select the appropriate devices to connect the end device to the network. The two most common devices used are hubs and switches. A hub receives a signal, regenerates it, and sends the signal over all ports. The use of hubs creates a logical bus. This means that the LAN uses multiaccess media. The ports use a shared bandwidth approach and often have reduced performance in the LAN due to collisions and recovery. Although multiple hubs can be interconnected, they remain a single collision domain.A switch receives a frame and regenerates each bit of the frame on to the appropriate destination port. This device is used to segment a network into multiple collision domains. Unlike the hub, a switch reduces the collisions on a LAN.When selecting a device for a particular LAN, there are a number of factors that need to be considered. These factors include; cost,speed and types of ports/interface,expandability,manageably,additional features and services.When planning the installation of LAN cabling, there are four physical areas to consider; work area, telecommunications room, also known as the distribution facility, backbone cabling, also known as vertical cabling, distribution cabling, also known as horizontal cabling.Horizontal cabling refers to the cables connecting the telecommunication rooms with the work areas. The maximum length for a cable from a termination point in the telecommunication room to the termination at the work area outlet must not exceed 90 meters. This 90 meter maximum horizontal cabling distance is referred to as the permanent link because it is installed in the building structure. The horizontal media runs from a patch panel in the telecommunications room to a wall jack in each work area. Connections to the devices are made with patch cables.Backbone cabling refers to the cabling used to connect the telecommunication rooms to the equipment rooms, where the servers are often located. Backbone cabling also interconnects multiple telecommunications rooms throughout the facility. These cables are sometimes routed outside the building to the WAN connection or ISP. Backbones, or vertical cabling, are used for aggregated traffic, such as traffic to and from the Internet and access to corporate resources at a remote location. A large portion of the traffic from the various work areas will use the backbone cabling to access resources outside the area or facility. Therefore, backbones typically require high bandwidth media such as fiber-optic cabling. Choosing the cables necessary to make a successful LAN or WAN connection requires consideration of the different media types. As you recall, there are many different Physical layer implementations that support multiple media types: UTP (Category 5, 5e, 6, and 7), fiber-optics, wireless.The total length of cable required to connect a device includes all cables from the end devices in the work area to the intermediary device in the telecommunication room (usually a switch). Attenuation is reduction of the strength of a signal as it moves down a media. The longer the media, the more attenuation will affect the signal. At some point, the signal will not be detectable. Cabling distance is a significant factor in data signal performance. Signal attenuation and exposure to possible interference increase with cable length. There are types of interfaces in networking that corresponds to their designed functionality, namely; Straight-through UTP Cables, Crossover UTP Cables. A straight-through cable has connectors on each end that are terminated the same in accordance with either the T568A or T568B standards. Identifying the cable standard used allows you to determine if you have the right cable for the job. More importantly, it is a common practice to use the same color codes throughout the LAN for consistency in documentation.For two devices to communicate through a cable that is directly connected between the two, the transmit terminal of one device needs to be connected to the receive terminal of the other device.The cable must be terminated so the transmit pin, Tx, taking the signal from device A at one end, is wired to the receive pin, Rx, on device B. Similarly, device B's Tx pin must be connected to device A's Rx pin. If the Tx pin on a device is numbered 1, and the Rx pin is numbered 2, the cable connects pin 1 at one end with pin 2 at the other end. These "crossed over" pin connections give this type of cable its name, crossover.The various LAN and WAN media types and their associated cables and connectors were considered so that the most appropriate interconnection decisions can be made.

Determining the number of hosts and subnets in a network required now - and simultaneously planning for future growth - ensures that data communications are available at the best combination of cost and performance.Similarly, a planned and consistently implemented addressing scheme is an important factor in ensuring that networks work well with provisions to scale as needed. Such addressing schemes also facilitate easy configuration and troubleshooting.Terminal access to routers and switches is a means to configure addresses and network features on these devices.

Chapter 8 OSI Physical layer

The OSI Physical layer makes available the means to transport across the network media the bits that make up a Data link layer frame. This layer allows a complete frame from the data link layer and encodes it as a series of signals that are transmitted onto the local media. The encoded bits that comprise a frame are received by either an end device or an intermediate device. The physical media and associated connectors, a representation of bits on the media, encoding of data and control information, and transmitter and receiver circuitry on the network devices are required Physical layer elements for the delivery of frames across the local media. The purpose of the Physical layer is to create the electrical, optical, or microwave signal that represents the bits in each frame. These signals are then sent on the media one at a time. There are three basic forms of network media on which data is represented namely copper cable, fiber, wireless. The representation of the bits depends on the type of media. For copper cable media, the signals are patterns of electrical pulses. For fiber, the signals are patterns of light and for the wireless media the signals are pattern of radio transmissions. In addition, there are three elementary roles that physical layer take part, the physical components, data encoding, and signaling. The physical elements refer to the electronic hardware devices, media and connectors that transmit and carry signals to represent the bits. Encoding is a method of converting a stream of data bits into a predefined code. Signaling is the method of representing the bits into electrical, optical, or wireless signals that represent the 1’s and 0’s on the media. However, the speed of transfer of bits varies in type of media and it can be measured through bandwidth, throughput and goodput. The capacity of a medium to carry data is describe as bandwidth. Throughput is the measure of the transfer of bits across the media over a given period of time. On the other hand, goodput measures the transfer of usable data. The physical layer is concerned with network media and signaling. This layer produces the representation and groupings of bits as voltages, radio frequencies, or light pulses. The most commonly used media for data communication is cabling that uses copper wires to signal data and control bits between network devices. Nowadays, fiber optic cable is an alternative replacement for copper cables and somehow varies in speed, capacity and expense.

Coms113 Data Communication