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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 ty

Chapter Six

Networking Hardware

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

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

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

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

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

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:

when operating system is loading

other devices may stop working

transmission

IRQ (Interrupt Request Line)

Figure 6-15: Computer resource settings in Windows 2000

IRQ (Interrupt Request Line)

CMOS (complementary metal oxide

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

Connectivity devices that regenerate and amplify an analog or digital signal

Figure 6-16: Repeaters

Multiport repeater containing multiple ports

to interconnect multiple devices

Figure 6-17: Detailed diagram of a hub

Elements shared by most hubs (cont.):

 Traffic (transmit or receive) LED

 Collision LED (Ethernet hubs only)

 Power supply

 Ventilation fan

Figure 6-18: Hubs in a network design

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

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)

Choosing the Right Hub

Factors to consider when selecting the right hub for your network:

Like a repeater,

a bridge has a

single input and

single output port

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

Spanning tree algorithm

modify the way multiple bridges work together, in order

to avoid such patterns

Cut-Through Mode and Store 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

These higher-layer switches may also be

called routing switches or application

switches

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

Router Features and Functions

Filter out broadcast transmission to alleviate

network congestion

Prevent certain types of traffic from getting to a

network

Support simultaneous local and remote activity

Provide high network fault tolerance through

redundant components

Monitor network traffic and report statistics to a MIBDiagnose internal or other connectivity problems and trigger alarms

Router Features and Functions

Static routing

 Technique in which a network administrator programs

a router to use a specified paths between nodes

Dynamic routing

 Automatically calculates best path between nodes

and accumulates this information in a routing table

Hop

 Term used in networking to describe each trip data take from one connectivity device to another

Router Features and Functions

Figure 6-28: The placement of routers on a LAN

Routing Protocols

protocols

In addition to its ability to find the best path, a

routing protocol can be characterized according to its convergence time and bandwidth overhead

Routing Protocols

The four most common routing protocols:

 RIP (Routing Information Protocol) for IP and IPX

 OSPF (Open Shortest Path First) for IP

 EIGRP (Enhanced Interior Gateway Routing Protocol) for IP, IPX, and AppleTalk

 BGP (Border Gateway Protocol) for IP

Brouters and Routing Switches

Bridge router

 Also called a brouter

 Industry term used to describe routers that take on some characteristics of bridges

Routing switch

 Router hybrid that combines a router and a switch

Combination of networking hardware and

software that connects two dissimilar kinds of networks

Popular types of gateways include:

 E-mail gateways

 IBM host gateways

 Internet gateways

 LAN gateways

Installing a NIC involves attaching it to the bus (or port), installing the NIC device drivers, and

configuring its settings

Firmware combines software and hardware

An IRQ is the means by which a device can request attention from the CPU

Chapter Summary

Repeaters are connectivity devices that perform the regeneration of a digital signal

At its most primitive, a hub is a multiport repeater

A MIB is a collection of data used by

management programs to analyze network

performance and problems

Bridges resemble repeaters in that they have a single input and single output port, but differ from repeaters because they can interpret the data

they transmit

Chapter Summary

Switches, like hubs, subdivide a network into

smaller logical pieces

A switch running in cut-through mode will read a frame’s header and decide where to forward the data before it receives the entire packet

In store and forward mode, switches read the

entire data frame and check it for accuracy

before transmitting it

In addition to improving bandwidth, switches can create virtual local area networks (VLANs)

Chapter Summary

A router is a multiport device that can connect

dissimilar LANs and WANs running at different

transmission speeds and using a variety of protocols

To determine the best paths across networks, routers communicate with each other using routing protocolsThe networking industry has adopted the term

“brouter” to describe routers that take on some

characteristics of bridges

Gateways are combinations of networking hardware and software that connect two dissimilar kinds of

networks