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 6-20:
Stackable hubs
Figure 6-21:
Rack-mounted
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 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
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
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 MIB
Diagnose 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
To determine the best path, routers
communicate with each other through routing
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

Convergence time
The time it takes for a router to recognize a best path in the
event of a change or outage

Bandwidth overhead
Burden placed on an underlying network to support the
routing protocol
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
Gateways
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
Chapter Summary
Network interface cards (NICs) come in a variety of
types
In addition to network adapters that interface with
network cabling, network adapters can be designed
for wireless transmission
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
protocols
The 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