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Learn about LAN connectivity hardware, network adapters, and troubleshooting techniques. Explore various types of network adapters and their installation procedures. Discover IRQ assignments and the importance of CMOS in networking hardware.
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Chapter Six Networking Hardware
Objectives • Identify functions of LAN connectivity hardware • Install and configure a network adapter (network interface card) • Identify problems associated with connectivity hardware
Objectives • Describe the factors involved in choosing a network adapter, hub, switch, or router • Describe the functions of repeaters, hubs, bridges, switches, and gateways • Describe the uses and types of routing protocols
Network Adapters • Also called network interface cards (NICs) • Connectivity devices enabling a workstation, server, printer, or other node to receive and transmit data over the network media • In most modern network devices, network adapters contain the data transceiver
Types of Network Adapters • For a desktop or tower PC, network adapter is likely to be a type of expansion board • Expansion boards connect to the system board through expansion slots • The circuit used by the system board to transmit data to the computer’s components is the computer’s bus
Types of Network Adapters • PC bus types you may encounter: • Industry Standard Architecture (ISA) • MicroChannel Architecture (MCA) • Extended Industry Standard Architecture (EISA) • Peripheral Component Interconnect (PCI) Figure 6-1: The four primary bus architectures
Types of Network Adapters Figure 6-2: A system board with multiple bus types
Types of Network Adapters • PCMIA • Developed in early 1990s to provide standard interface for connecting any type of device to a portable computer • More commonly known as PC Cards Figure 6-3: Typical PC Card network adapter
Types of Network Adapters • USB (universal serial bus) port • Standard external bus that can be used to connect multiple types of peripherals Figure 6-4: A USB network adapter
Types of Network Adapters Figure 6-5: A parallel port network adapter
Types of Network Adapters Figure 6-6: Wireless network adapters
Types of Network Adapters Figure 6-7: A variety of Ethernet network adapters
Types of Network Adapters Figure 6-8: Token Ring network adapters
Types of Network Adapters Figure 6-9: Ethernet network adapters for printers
Installing Network Adapters • To install modern network adapters, first install hardware, then install software shipped with NIC • In some cases you must perform a third step: • Configure the firmware • Electrically erasable programmable read-only memory (EEPROM) • Type of ROM found on a circuit board • Configuration information can be erased and rewritten through electrical pulses
Installing and Configuring Network Adapter Hardware Figure 6-10: A properly inserted network adapter
Installing and Configuring Network Adapter Hardware Figure 6-11: Installing a PC Card network adapter
Installing and Configuring Network Adapter Hardware • Jumper • Small, removable piece of plastic that contains a metal receptacle Figure 6-12: A jumper and a row of pins indicating two different settings
Installing and Configuring Network Adapter Hardware • DIP switch • Small, plastic toggle switch that represents “on” or “off” status Figure 6-13: DIP switches on a NIC
Installing and Configuring Network Adapter Software • Ensure that the correct device driver is installed for the network adapter and that it is configured properly • Device driver • Software that enables an attached device to communicate with computer’s operating system
Installing and Configuring Network Adapter Software Figure 6-14: Windows 2000 Upgrade Device Driver Wizard
IRQ (Interrupt Request Line) • Message to the computer that instructs it to stop what it is doing and pay attention to something else • An interrupt is the wire on which a device issues voltage to signal this request • Each interrupt must have a unique IRQ number
IRQ (Interrupt Request Line) Table 6-1: IRQ assignments
IRQ (Interrupt Request Line) • When two devices attempt to use the same IRQ, any of the following problems may occur: • Computer may lock up or “hang” either upon starting or when operating system is loading • Computer may run much slower than usual • Though computer’s network adapter may work properly, other devices may stop working • Video or sound card problems may occur • Computer may fail to connect to the network • Computer may experience intermittent data errors during transmission
IRQ (Interrupt Request Line) Figure 6-15: Computer resource settings in Windows 2000
IRQ (Interrupt Request Line) • CMOS (complementary metal oxide semiconductor) • Firmware on a PC’s system board that enables you to change its devices’ configurations • Information saved in CMOS is used by the computer’s BIOS (basic input/output system) • BIOS is a simple set of instructions enabling a computer to initially recognize its hardware
Memory Range and Base I/O Port • Memory range • Hexadecimal number indicating the area memory that the network adapter and CPU will use for exchanging, or buffering, the data • Base I/O port • Setting that specifies, in hexadecimal notation, which area of memory will act as a channel for moving data between the network adapter and CPU
Firmware Settings • Once you have adjusted the network adapter’s system resources, you may need to modify its transmission characteristics • These settings are held in the adapter’s firmware • Loopback plug • Plugs into port and crosses over the transmit line to the receive line so that the outgoing signal can be redirected back into the computer for testing
Choosing the Right Network Adapter Table 6-2: Network adapter characteristics
Repeaters • Connectivity devices that regenerate and amplify an analog or digital signal Figure 6-16: Repeaters
Hubs • Multiport repeater containing multiple ports to interconnect multiple devices Figure 6-17: Detailed diagram of a hub
Hubs • Elements shared by most hubs: • Ports • Uplink port • Port for management console • Backbone port • Link LED
Hubs • Elements shared by most hubs (cont.): • Traffic (transmit or receive) LED • Collision LED (Ethernet hubs only) • Power supply • Ventilation fan
Hubs Figure 6-18: Hubs in a network design
Hubs • Passive hubs • Only repeats signal • Intelligent hubs • Possesses processing capabilities
Standalone Hubs • Hubs that serve a group of computers that are isolated from the rest of the network • Best suited to small, independent departments, home offices, or test lab environments • Disadvantage to using a single hub for many connection ports is that it introduces a single point of failure on the network
Stackable Hubs • Physically designed to be linked with other hubs in a single telecommunications closet Figure 6-21: Rack-mounted stackable hubs Figure 6-20: Stackable hubs
Modular Hubs and Intelligent Hubs • Modular hubs • Provide a number of interface options within one chassis • Intelligent hubs • Also called managed hubs • Network administrators can store the information generated by intelligent hubs in a MIB (management information base)
Installing a Hub • As with network adapters, the best way to ensure a hub is properly installed is to follow the manufacturer’s guidelines Figure 6-22: Connecting a workstation to a hub
Choosing the Right Hub • Factors to consider when selecting the right hub for your network: • Performance • Cost • Size and growth • Security • Management benefits • Reliability
Bridges • Like a repeater, a bridge has a single input and single output port • Unlike a repeater, it can interpret the data it retransmits Figure 6-23: A bridge
Bridges • Filtering database • Collection of data created and used by a bridge that correlates the MAC addresses of connected workstations with their locations • Also known as a forwarding table Figure 6-24: A bridge’s use of a filtering database
Bridges • Spanning tree algorithm • Routine that can detect circular traffic patterns and modify the way multiple bridges work together, in order to avoid such patterns • Transparent bridging • Method used on many Ethernet networks • Source-route bridging • Method used on most Token Ring networks • Translation bridging • Method that can use different logical topologies
Switches • Subdivide a network into smaller logical pieces Figure 6-25: Examples of LAN switches
Cut-Through Mode andStore and Forward Mode • Cut-through mode • Switching mode in which switch reads a frame’s header and decides where to forward the data before it receives the entire packet • Cut-through switches can detect runts, or packet fragments • Store and forward mode • Switching mode in which switch reads the entire data frame into its memory and checks it for accuracy before transmitting the information
Using Switches to Create VLANs • Virtual local area networks (VLANs) • Network within a network that is logically defined by grouping its devices’ switch ports in the same broadcast domain • Broadcast domain • Combination of ports that make up a Layer 2 segment and must be connected by a Layer 3 device
Using Switches to Create VLANs Figure 6-26: A simple VLAN design
Higher-Layer Switches • Switch capable of interpreting Layer 3 data is called a Layer 3 switch • Switch capable of interpreting Layer 4 data is called a Layer 4 switch • These higher-layer switches may also be called routing switches or application switches
Routers • Multiport connectivity device • Can integrate LANs and WANs running at different transmission speeds and using a variety of protocols • Routers operate at the Network layer (Layer 3) of the OSI Model
Router Features and Functions • Modular router • Router with multiple slots that can hold different interface cards or other devices Figure 6-27: Routers