Transcript Network Architecture

Chapter 11
PCs on a Network
You Will Learn…
• How local networks are structured
• How to connect a PC to a LAN and divide a
•
network into segments
How to connect networks to each other
Network Architecture
• Describes overall design of the network

Physical components
 Network technologies
 Interfacing software
 Protocols needed to establish reliable
communication among nodes
Physical Network Architectures
• Ethernet (most popular)
• Token ring
• FDDI (Fiber Distributed Data Interface)
• Wireless LAN technology
Network Architecture Terminology
•
Network adapter



•
Most often an expansion card called a network interface
card (NIC)
Must match type and speed of physical network in use
Network port must match type of connectors used on the
network
Network protocols


Hardware protocols (eg, Ethernet, Token Ring)
OS protocols (eg, NetBEUI, TCP/IP)
continued…
Network Architecture Terminology
• Packets, datagrams, or frames

Packets have maximum size depending on type of
network
• CRC (cyclical redundancy check)

Technique of calculating and comparing values
Ethernet Variations, Distinguished
by Speed
•
10-Mbps Ethernet

•
100-Mbps Ethernet or Fast Ethernet


•
Uses either shielded twisted-pair (STP) cable, unshielded
twisted-pair (UTP) cable, or coaxial cable
Uses UTP or STP cable
100BaseFX uses fiber-optic cable (single-mode, multimode, and plastic)
1000-Mbps Ethernet of Gigabit Ethernet

Uses twisted-pair and fiber-optic cable
Cable Types Used with Ethernet
continued…
Cable Types Used with Ethernet
Comparison of Ethernet Version
Cable Types
Ethernet Topology
• Bus topology

Connects each node in a line
 Does not have a centralized point of connection
• Star topology

Connects all nodes to a centralized hub
 More popular
Ethernet Topology: Bus or Star
Ethernet Using Star Topology
Ethernet Hub
Ethernet Using
Star Bus Topology
Ethernet Network
• A passive network
• Contention-based system

Each computer contends for an opportunity to
transmit on the network
 Requires collision control
How Ethernet Controls
Data Traffic
• CSMA/CD (Carrier Sense Multiple Access
•
•
with Collision Detection)
CSMA/CA (Carrier Sense Multiple Access
with Collision Avoidance)
Token method
Repeaters
Token Ring
• Physical star; logical ring
• Data packet is preceded by a token
• Transmits data at 4 Mbps or 16 Mbps
• Uses a centralized device called a MAU
(Multistation Access Unit)
Token Ring
FDDI
• Use a token that travels in a ring
• Data frames travel on the ring without the
•
•
token
Multiple nodes can have data on the ring at the
same time
Provides data transfer at 100 Mbps
Wireless LANs (WLANs)
•
Make connections using wireless NICs

•
•
Can be used in combination with a wired LAN
Standards

•
•
Include antennas or infrared transmission to send and
receive signals in places where networking cables are
difficult to install

1999 IEEE 802.11b (Wi-Fi, AirPort)
Bluetooth
Slower than wired networks
Security is an issue
WLANs
Connecting a PC to a Network
•
Requirements



•
•
•
NIC
Network cable (patch cable)
Device for PC to connect to (eg, hub)
How NICs work and how to install them
How to set up a network protocol
Using bridges and switches to divide a network into
segments for improved performance
How NICs Work
• Plug into motherboard expansion slot
• Provide port(s) on back of card for connection
•
to network
Manage communication and hardware network
protocol for the PC
A FDDI Network Card
A Token Ring Network Card
An Ethernet Network Card
How NICs Work
•
•
Network in use is transparent to applications software
using it
Network card

Sends and receives data to and from system bus in parallel
 Sends and receives data to and from network in series
 Uses a transceiver for signal conversion
•
Network nodes are identified by a MAC (Media
Access Control) address
Ethernet Combo Card
Network Cards
• Requirements

IRQ
 I/O address
 Upper memory addresses (for DOS and
Windows 9x real mode)
• May be PnP or can use jumpers or DIP
switches to determine resources to request
Considerations When Selecting a
Network Card
• Speed and type of network (except for wireless
•
•
connections)
Type of cable (shielded twisted-pair, coaxial,
or fiber-optic)
Type of slot (PCI or ISA)
Installing a Network Card and
Protocol under Windows 9x
• Windows 95 supports Ethernet, token ring, and
•
ARCnet networking cards
Windows 98 supports ATM, Ethernet, token
ring, FDDI, IrDA, and ARCnet networking
cards
Installing a NIC Using
Windows 9x
• Set DIP switches or jumpers and physically
•
•
•
install the card
Turn on PC; Windows detects and configures
new device
Select Device Manager to verify installation
View Properties window to confirm resources

IRQ and I/O address of the card can be found on
Resources tab
Using Device Manager to Verify
Installation
Installing NetBEUI Using Windows
98
Assigning NetBIOS Names
• Only configuration required by NetBEUI
• Limited to 15 characters
• Windows 9x assumes that a computer name is
•
a NetBIOS name
Access Control Panel; double-click Network
icon; click Identification tab
Assigning NetBIOS Names
Assigning NetBIOS Names
Installing a NIC Under
Windows 2000/XP
•
•
Windows 2000 automatically detects an installed card
and guides installation of drivers
Options for verifying error-free installation

Device Manager
 Network and Dial-Up Connections applet in Control Panel
•
•
Installing NetBEUI Protocol will automatically bind
itself to the NIC providing the connection
Give a host name to the computer
NIC Properties Window Under
Windows 2000
Assigning a Host Name Under
Windows 2000
Installing a Wireless NIC
•
Use NIC’s configuration software to specify wireless
network parameters



•

State
Current Channel
Current Tx Rate
Throughput, Link Quality, and Signal Strength
Computer must be within acceptable range of an
access point or another wireless device that it will
communicate with directly

Distance determined by type of technology used
Wireless NIC Configuration
Software
Configuring a Wireless NIC
Changing NIC Functions
• Mode
• SSID (service set identifier)
• Tx Rate
• PS Mode
Enabling Encryption on a Wireless
LAN
Symptoms of NIC Problems
•
•
•
•
•
Cannot make connection to network
Network Neighborhood or My Network Places does
not show any other computers on the network
Error message during installation
Device Manager shows yellow exclamation point or
red X beside name of NIC
No lights on NIC
Troubleshooting a Network
Connection
•
•
•
•
•
•
•
Check connections in rest of network
Reboot PC and reset network connections
Make sure NIC and its drivers are installed
For TCP/IP network, use ping 127.0.0.1 command to
determine whether NIC and IP protocol are working
Check for an IRQ conflict
Check cabling and ports
Confirm most current version of motherboard BIOS
Segmenting a Network
• Decreases amount of traffic on overall network
• Done through use of bridges and switches

More intelligent than hubs
 Make decisions about whether or not to allow
traffic to pass, or where to forward that traffic
 Use MAC addresses, which they store in routing
tables, to determine where to send packets
Bridges
Bridges
Bridges
Bridges and Switches
•
Bridges



•
Send broadcast messages; do not work well with large
networks
Effective at separating high-volume areas on a LAN
Work best when used to connect LANs that usually do not
communicate outside their immediate network
Switches

Send a packet only to network segment for which it is
destined
Bridges Compared with Switches
Connecting Networks
• Communication between networks uses
•
TCP/IP (not MAC addresses)
Methods of network connection

Routers
 Bandwidth technologies
Routers
•
•
•
Use IP addresses to
determine path by which to
send a packet
More efficient than switches
in choosing routes for
packets over long distances
Stateless devices

Unconcerned about data;
concerned about destination
address of data
Using Routers to Connect Networks
Networking Protocols
•
A router can transmit a data packet to a remote
network only if a routable protocol:

•

Routable

•
Was used to produce the data packet
Can be routed to a remote network

TCP/IP
IPX/SPX
Not routable

NetBEUI
Brouter
• Functions both as a bridge and a router
• As a router

Can route routable protocols (TCP/IP and IPX/SPX
packets)
• As a bridge

Forwards packets that are not routable (NetBEUI
packets) to other local networks
Bandwidth
• Measures how much data can travel over a
•
•
given communication system in a given
amount of time
Also called data throughput or line speed
Greater bandwidth = faster communication
Bandwidth Technologies
continued…
Bandwidth Technologies
continued…
Bandwidth Technologies
Common Bandwidth Technologies
• Regular telephone lines
• Cable modem
• ISDN (Integrated Services Digital Network)
• DSL (Digital Subscriber Line)
• Satellite access
• Wireless access
Chapter Summary
• How local networks are built
• How bridges and switches can segment large
•
•
•
local networks
How routers connect networks
Technologies used to connect PCs and
networks to the Internet
Servicing PCs that are connected to a network