NETWORKING
PHYSICAL
CABLING
LOGICAL
NETWORK
NETWORK
TOPOLOGIES Classification TOPOLOGIES
PROTOCOLS
HARDWARE
TYPES
Linear
Coaxial
Ethernet
OSI model
Hubs,
LAN
Star
Twisted Pair
Token Ring
TCP/IP
Switches
MAN
Ring
Fiber Optic
FDDI
IPX
Repeaters,
WAN
Tree
ATM
NetBIOS/NetBEUI
Bridges
CAN
Mesh
Routers,
TAN
Brouters
Gateway
DEFINITIONS: A NETWORK consists of two or more computers that are linked in
order to share resources (such as printers and CD-ROMs), exchange files, or allow
electronic communications. The computers on a network may be linked through
cables, telephone lines, radio waves, satellites, or infrared light beams.
 When any one of these computers are connected to a LAN they are referred
to as a WORKSTATION. All computing devices on a network; workstations,
printers, etc., are referred to as NODES.

When connecting a workstation, the interface hardware is referred to as an
ADAPTER. Networking adapters are also commonly referred to as
NETWORK INTERFACE CARDS or NICS.


Most NIC's break the information into FRAMES or PACKETS of information.
The LAN connection for a printer, however, is referred to as a PRINT
SERVER and not a NIC.
The SERVER is the computer whose resources are shared with other
computers.
SEGMENTS are trunks of cabling connecting devices to a routing device.
A BACKBONE is the foundation of the LAN/WAN where the servers are linked
together in a common series of concentration devices.
A network where a server acts as a dedicated server and supplies information
to workstations is called a CLIENT/SERVER network.
A PEER-TO-PEER network is a network where all computers act as both
servers and clients and data files can be shared. This network has no one
dedicated server.





A basic network is made up of primary components.
1. A hub (which acts as the traffic cop on your small information highway. The
hub acts as a switch to route information from one terminal to another
through the use of cables.
2. an interface card (hardware in each computer that connects to the hub)
3. a server (the central storage computer for information).
4. special cabling
5. computers, printers, scanners, etc.
TYPES OF NETWORKS: The three basic types of networks include:

Local Area Network (LAN): A Local Area Network (LAN) is a network that is
confined to a relatively small area. It is generally limited to a geographic area




such as a writing lab, school, or building. Rarely are LAN computers more
than a mile apart.
Metropolitan Area Network (MAN): A Metropolitan Area Network (MAN)
covers larger geographic areas, such as cities or school districts. By
interconnecting smaller networks within a large geographic area, information
is easily disseminated throughout the network. Local libraries and government
agencies often use a MAN to connect to citizens and private industries.
Wide Area Network (WAN): Wide Area Networks (WANs) connect larger
geographic areas, such as Florida, the United States, or the world. Dedicated
transoceanic cabling or satellite uplinks may be used to connect this type of
network.
CAN: Campus Network
TAN: Tine Area Networks are 2 - 3 computers networked at home or in a
small business.
NETWORK TOPOLOGIES
There are two types of topology: physical and logical.


The physical topology of a network refers to the configuration of cables,
computers, and other peripherals.
Logical topology is the method used to pass the information between
workstations as can be seen in protocols.
PHYSICAL TOPOLOGIES
1. LINEAR BUS
A linear bus topology or 10BASE2 bus topology consists of a main run of cable
with a terminator at each end. All nodes (file server, workstations, and peripherals)
are connected to the linear cable. ETHERNET AND LOCALTALK networks use a
linear bus topology. Networking is simple. The network may have or hub or not.
DISADVANTAGES




Entire network shuts down if there is a break in the main cable.
Terminators are required at both ends of the backbone cable.
Difficult to identify the problem if the entire network shuts down.
Not meant to be used as a stand-alone solution in a large building.
2. STAR TOPOLOGY
A star topology is designed with each node (file server, workstations, and
peripherals) connected directly to a central network hub or concentrator. A
concentrator is a device that provides a central connection point for cables from
workstations, servers, and peripherals. Most concentrators contain the ability to
amplify the electrical signal they receive.
DISADANTAGES


Requires more cable length than a linear topology. If the hub or concentrator
fails, nodes attached are disabled.
More expensive than linear bus topologies because of the cost of the
concentrators.
This configuration is common with twisted pair cable; however, it can also be used
with coaxial cable or fiber optic cable. A simple star topology is also used for
10BASE-T ETHERNET networks.
3. STAR-WIRED RING (TOKEN RING)
A STAR-WIRED RING topology may appear (externally) to be the same as a star
topology. Instead of having a concentrator at the center of the ring network, there is
a device called a MAU (MULTISTATION ACCESS UNIT). Internally, the MAU of a
star-wired ring contains wiring that allows information to pass from one device to
another in a circle or ring. The MAU does the same thing a hub does, but it works
with TOKEN RING networks instead of Ethernet.
A Token ring using Unshielded twisted pair in star or modified star transfers at 4
Mbps.
A Token Ring configuration using shielded twisted pair in star or modified star
configuration transfers at 4 or 16 Mbps. A local Ring Hub allows four-node
connections on one MAU port cable. 64 - 72 (max.) nodes are recommended per ring
for optimal performance. A double ring may have a maximum of 12 MAU's, each
which can support 8 nodes. THe maximum distance between MAU and workstation is
45 m.; MAU to MAU is 120 m.
In difference, FDDI (FIBER DISTRIBUTED DATA INTERFACE), pronounced fidee, also uses A COMPLEX token ring topology. FDII networks run on optical fiber
cables instead of copper cabling. It's similar to Token Ring but can be connected to
2 MAUS so if one fails, the other can work. The FDDI has an added alternate ring. If
a break occurs in either ring, it automatically reroutes the data transmission to the
alternate ring. This ring supports speeds up to 100 Mbps. Has become the defacto
high speed backbone. Maximum stations are 1000. THe distance limitation is 2 miles.
4. TREE TOPOLOGY
A tree topology combines characteristics of linear bus and star topologies. It consists
of groups of star-configured workstations connected to a linear bus backbone cable.
Tree topologies allow for the expansion of an existing network, and enable schools to
configure a network to meet their needs.
DISADVANTAGES



Overall length of each segment is limited by the type of cabling used.
If the backbone line breaks, the entire segment goes down.
More difficult to configure and wire than other topologies.
5-4-3 RULE: A consideration in setting up a tree topology using Ethernet protocol
is the 5-4-3 RULE. One aspect of the Ethernet protocol requires that a signal sent
out on the network cable reach every part of the network within a specified length of
time. Each concentrator or repeater that a signal goes through adds a small amount
of time.




This leads to the rule that between any two nodes on the network there can
only be a maximum of 5 segments
connected through 4 repeaters/concentrators.
In addition, only 3 of the segments may be populated (trunk) segments if
they are made of coaxial cable. A populated segment is one which has one or
more nodes attached to it.
This rule does not apply to other network protocols or Ethernet networks
where all fiber optic cabling is used.
2. MESH TOPOLOGY
In a mesh topology, each device on the network is networked (cabled) to eachother.
ADVANTAGES: Mesh topologies are installed where FAULT TOLERANCE is important.
A single cable failure would not stop network communications between any two
computers. The mesh topology is highly fault tolerant. DISADVANTAGES: More
expensive and difficult to install. Requires more cabling since each device is cabled to
eachother.
CABLING
XBaseX classification: 10BaseT, 100BaseT and 10Base2 are networking standards
and there are others.


The first number is an indication of the transmission speeds involved. It is
listed in Mbps (Mega Bits Per Second).
The second portion designates Baseband or Broadband, how the data is
sent across the cabling. In Baseband one signal takes up the entire bandwith
of the cable. This data is digital.
With Broadband, the total bandwith of the cabling is divided and there will be many
signals traveling through the cabling at a time. Broadband is analog. Broadband
signals can travel father then Baseband.

The last portion is an indication of wire type and the approximate distances
involved or the type of cabling.
TYPES OF CABLE
There are three types of network wiring.



Coaxial
Twisted-Pair
Fiber
Each type of cabling has different requirements if it is to meet network standards.
IEEE 802.X SPECIFICATIONS
THE INSTITUTE OF ELECTRICAL AND
ELECTRONIC ENGINEERING (IEEE) published
the 802 specifications. This designed standards for
the physical components of a network.








802.1 Internetworking
802.2 Logical Link Control (LLC)
802.3 CSMA/CD LANs (Ethernet)
802.4 Token Bus LAN
802.5 Token Ring LAN
802.6 MAN
802.7 Broadband Technical Advisory
Groups
802.8 Fiber Optic Technical Advisory
Group



802.9 Integrated Voice and Data Networks
802.10 Network Security
802.11 Wireless Network, etc.
The 802 standards break the Data Link Layer
further:


LOGICAL LINK CONTROL (LLC) - For
error correction and control.
MEDIA ACCESS CONTROL (MAC) - gives
physical addresses to device. Like the TO:
and FRO: of an envelope.
1. COAXIAL CABLE
Following the IEEE 802.3 Standard, coaxial cable is used for 10BASE2 (thin-net,
CheaperNet) and 10BASE5 (thick-net) networking. No concentrator is needed.
10BASE2 is not the most reliable cabling. 10BASE2 and 10BASE5 are used in a
LINEAR BUS topology.
With Ethernet 10Base2




255 devices cab be connected
maximum length of a segment is 185 meters
is usually standard industry RG-58 cable
o has a solid copper center conductor
o braided outer conductor
o 50 ohm cable
o requires termination at both ends of segment using 50 ohm
terminator.
Each computer connects to the computer with a T-Connector (BNC - British
Naval Connector).
With Ethernet 10Base5




is usually standard industry RG-8 or RG-11 cable
maximum length of a segment is 500 meters
50 ohm cable
requires termination at both ends of segment using 50 ohm terminator.
10Base5 wire is connected not by BNC connectors but by AUI connectors. AUI
connectors are a DB15 connector, that is, a D-shaped plug with 15 pins. These
look just like RS-232 modem connectors, only about half as broad. These are
common on equipment such as routers.
10Base5 cable may also be connected by a vampire connector with clamps holding
the cable in place. A vampire tap is a connection to a coaxial cable in which a hole is
drilled through the outer shield of the cable so that a clamp can be connected to the
inner conductor of the cable. This cable connection is made with a unit that clamps
onto and "bites" into the cable, hence the vampire name.
2. TWISTED PAIR CABLING (STP and UTP)
Coaxial and SHIELDED TWISTED PAIR (STP) have a copper braid of foil that
offers good resistance to electrical noise, but the extra foil creates a larger, thicker
cable, making it difficult to pull the cable through conduit and walls during
installation. UNSHIELDED TWISTED PAIR (UTP) does not contain this aluminum
shielding and is thinner and therefore easier to install. It offers less resistance to
electrical noise.
STP is used in Token Ring, ARCnet and Appletalk networks. UTP is used in Star
Topologies.
Unshielded Twisted Pair(UTP) is the next step up from Coaxial. TP cabling is a cable
made up of four pairs of insulated copper wires. UTP are 8 copper conductor, four
pair wires.
RJ45 connectors are fitted on each end of the cable. They resemble a normal
telephone plug (RJ11) with the exception of eight pins rather than four. The RJ45
cable connects to a NETWORK PATCH PANEL which is connected to the hub. The
RJ45 is an 8 wire (4 pair) media connector.
EAI/TIA 568 COMMERCIAL BUILDING
WIRING STANDARD for Unshielded
TP(UTP):
UTP comes in levels of Category 1 - 5. The
Electronics Industries Association and the
Telecommunication Industries Association
(EIA/TIA) created this standard for Unshield
Twisted Pair cabling. The higher category cables
contain more wire paths and higher number
of twists to prevent EMI.




Category 1: not rated for performance
Category 2: used for telephone wiring sasta rate of 1 magabit per second.
Category 3: lowest level that can be
used for networking. Used for ETHERNET
10BASE-T. Data rate of 16 megabits per
second.Used for data up to 10 Mps
Category 4: used for Token Ring and

10BASE-T. Maximum dat rate is 20
megabits per second.
Category 5: used for Ethernet 10BASET. Maximum date rate of 155 megabits
per second. Used for voice/or data.
UTP (Unshieded Twisted Pair) is most commonly used in Category Three (CAT3) or
Category Five (CAT5). The difference between the ratings is the number of twists
per inch. Higher is better. CAT5 is probably the most commonly seen and used. It is
inexpensive, reliable, easy to maintain and expand.
COATING ON CABLES: Cable through the ceilings must be plenum-rated and
riser-rated and capable of withstanding environmental and fire conditions(riser)
without giving off toxic gases(plenum) when it burns. PVC rated is the least
expensive but highly flammable.
Stripping and Terminating a Cat5 Cable: Illustrated Tutorial.
3. FIBER OPTIC CABLE
Standard IEEE 802.8. Rather than using electrical impulses over wire, optical fiber
transmits data using pulses of light. It is expensive to install and maintain. The
average network administrator lacks the expertise to terminate each end. Fiber can
carry data as high as 622 megabits per second. Fiber is not affected by EMI like
copper cable and does build up a magnetic field to allow crosstalk. It is very lightweight compared to copper-based cable.
LOGICAL TOPOLOGIES
A protocol is a set of rules that governs the communications between
computers on a network. These rules include guidelines that regulate the
following characteristics of a network: access method, allowed physical
topologies, types of cabling, and speed of data transfer. Logical
topologies instruct the hardware how to packet and transmit
data across a physical topology.
1. ETHERNET
The Ethernet protocol is by far the most widely used. The Ethernet
protocol allows for linear bus, star, or tree topologies. Data can be
transmitted over twisted pair, coaxial, or fiber optic cable at speeds of
10 Mbps.
The foundations of Ethernet is CSMA/CD (Carrier Sense Multiple
Access/Collision Detection). In an Ethernet network, all computers
share a single network segment, called a collision domain. When 2
computers transmit data along the segment simutaneoulsy, collision
occurs. Each computer then can transmit data only when no other
computer is transmitting.
Ethernet uses CSMA/CD described in the IEEE standard 802.3.
Cabling
MAX
Distance/
Segment
Devices/
Segment
Topology
Max
IRLs
Max
Length of
Cable
Devices
Attached
To:
Termination Grounded
2.5km (1.5
miles)
Standard
Thick
Ethernet
(10Base5)
COAXIAL
1640 ft.
(500 m)
10 Mbps
Speed
100
Workstations
per trunk
maximum
lngth of
trunk 500
m.
Bus
2
entire
network
trunk
maximum
2500 m.
Backbone
by use of
transceivers
50-ohm
resistor
(both ends)
To earth
NICs with
built-in BNC
transceivers
50-ohm
resistor
(both ends)
To earth
5-4-3 RULE
925m
(3035 ft.)
Thin
Ethernet
(10Base2)
COAXIAL
Shielded
(STP)
10Base-T
TWISTED
PAIR
Unshielded
(UTP)
10Base-T
TWISTED
PAIR
607 ft.
(185 m)
10 Mbps
30
Workstations
per trunk
328 ft.
(100 m)
16 - 155
Mbps
328 ft.
(100 m)
10 Mbps
Speed
Bus
2
1024
workstations
per network
minimum
cable length
between
workstations
20"
Token
Ring
3
500m
Central hub
managed or
unmanaged
None
needed
Star
3
500m
Central hub
managed or
unmanaged
None
needed
1023
workstations
without
bridging
5-4-3 RULE
Workstations
only 328 ft.
from
concentrator
minimum
cable legnth
between
stations 8 ft.
1023
workstations
without
bridging
5-4-3 RULE
Unshielded
328 ft.
(UTP)
(100 m) Workstations
100Base-T 100 Mbps only 328 ft.
TWISTED
Speed
from
PAIR
concentrator
Star
3
500m
Central hub
managed or
unmanaged
None
needed
Star
2
4km
Fiberoptic
hub or
repeater
None
needed
minimum
cable legnth
between
stations 8 ft.
10Base-FL
FIBER
OPTIC
1.2 miles
(2
km)(w/5
segments
max. is
500m)
100 Mbps
- 2 Gbps
2
The Ethernet standard has grown to include faster networks.
Cable Type
Data Transfer
100BASE-T (fast
Ethernet)
Speed
100 megabits per
second
Maximum Distance
20 m.
100BASE-FX (Fast
Ethernet on optical
fibers)
none
100BASE-T4
20 m.
2. TOKEN RING
Uses IEEE Standard 802.5, Token Ring is very different from Ethernet. In token ring
a single packet is passed around the network. Every computer waits its turn. There are
no collisons. Token Ring has the same bandwidth as Ethernet. Too many computers
result in network slowness. FDDI is a faster Token Ring configuration (as described
above).
3. ATM (Asynchronous Transfer Mode
Following IEEE Standard 802.9, ATM is one of the newer topologies. It can carry
voice and data over network wire or fiber. ATM transmits packets as 53-byte cells that
have a variety of identifiers to detmine such things as Quality of Service or wich packet
is to be routed first. Packets are sent their need for bandwidth. For example, email
would have a low priority and voice and video a higher priority and be sent first. ATM
runs 25 - 622 megabits per second. It is also expensive.
NETWORK PROTOCOLS
On top of the Logical Topologies are protocols. Protocols handle the translation of
data from applications to the logical topology.
THe OSI model explain how a network should work. The lower the level the less
abstract and more concrete the layer is. Each layer communicates only with the layer
above or below it while moving data.
OSI MODEL (Open Systems Interconnect)
The seven-layer OSI (Open systems Interconnection) model, created by the ISO
(International Standards Organization), defines internetworking environments. It
provides a description of how software and hardware interact to permit communication
between computers. An interface separates each layer from those above and below it;
each layer provides services to the layer directly above it.
This handy mnemonic will help you keep the layers in proper order:
LAYER
Application
Layer
(Rx. the
7.
All
Application
6.
People
Presentation
5.
Seem
Session
4.
To
Transport
3.
Need
Network
2.
Data
Data Link
1.
Processing
Physical
FUNCTION
Allows application
processes to access
network services.
PROTOCOLS
FTP, SNMP,
SMPT NCP
HARDWARE
Gateway
dashboard of
your car. The
different
gauges make
you aware of
the
information
that you need
to know in
order to
maintain
speed limits
and optimal
performance
for your
vehicle.
Manages
communication
between
applications. Flow
control and error
recovery is handled
here.
Presentation
Layer
(RX. the
universal
signs both on
the highway
and inside
your vehicle.)
FORMAT Functions as the
network’s translator
– handles protocol
conversion, data
translation and
encryption, and
data compression.
The redirector
operates here.
NCP
Gateway
Session Layer
(Rx. the
designated
traffic lanes
TRAFFIC COP.
Provides
synchronization
between computers;
allows applications
on two computers to
establish a session.
None
Gateway
Transport
Layer
(Rx Speed
recognition
devices on a
highway)
RESPONSIBLE
FOR THE
ACCURACY OF
THE DATA
TRANSMISSION.
Ensures reliable
delivery of packets.
Repackages
messages, dividing
them into smaller
packets.
Uses protocols
TCP,
SPX(Sequenced
Packet
Exchange)
from IPX/SPX
stack, and
NWLink
(Microsoft's
implementation
of IPX/SPX),
NetBEUI
SPX and TCP
packets are
connection
Gateway
protocols.
Network Layer
(Rx highway
exit
numbering
scheme)
Establishes THE
UNIQUE
NETWORK
ADDRESS AND
MANAGES THE
TRANSPORT OF
INFORMATION
PACKETS
BETWEEN
DIFFERENT
NETWORKS.
Routes the packets
and determines the
best route for
sending them.
Manages network
traffic problems,
packet switching,
routing, and
reassembling data.
IP, IPX,
NetBEUI, DLC
Router, Brouter
Data Link
Layer
(Rx. Entry
ramp/toll
booth that
allows access
onto the
highway)
DETERMINES
HOW DEVICES
CONNECTED WILL
GAIN ACCESS.
Determines how 1's
nd 0's are
asssembled into
frames or packets of
data. Sends data
frames from the
Network Layer to
the Physical Layer.
Contains the
physical address of
a device. Like the
FROM: and TO: of
a envelope.
None
Bridge, Remote Bridge,
Brouter, Switch
Physical Layer
(Rx.
determining
if the road
infrastructure
will be built
of concrete
or asphalt.)
Transmits data bits
between computers.
Defines how 1's and
0's are interpreted
from the medium.
DEFINES CABLES,
NETWORK
INTERFACE
CARDS, AND
OTHER PHYSICAL
None
IEEE 802.X Standards
Ethernet, Token Ring,
FDDI
The NIC CARDS,
REPEATERS,
CONCENTRATORS/HUBS,
MAU's, SWITCHING
HUBS etc.
CABLES - IEEE 802.X
ASPECTS.
1. TCP/IP Network Protocol
1. DEFINITION: Stands for Transmission Control Protocol/Internet
Protocol. This is the protocol that carries data over the Internet. It is actually
a set of protocols
o PPP - Point to Point Protocol
o SMPT - Simple Mail Transport
o TCP - Transmission Control Protocol
o IP - Internet Protocol that handles addresses, etc.
o FTP - File Transfer Protocol
o MIME - Multipurpose Internet Mail Extensions, is more of a standard
than a protocol. Used by e-mail applications, it is a method for sending
files back and forth between computers through electronic mail. This
allows formatted documents created through word processors or
spreadsheet programs to be attached to an electronic mail message
and arrive on the other end exactly as they were sent.
TCP/IP uses 5 layers of the OSI model(1,2,3,4, and 7)
2. IP ADDRESSES: To communicate on the Internet, computers must have
unique identifiers in order to differentiate one computer from another. This is
accomplished through IP addresses. IP is made up of a 32-bit address or 4
"octet" address. An IP address consists of 4 parts separated by decimal
points.
199.250.132.1
128.30.7.10
Every host has at least one unique IP address. In addition, every router has a
unique IP address for every network adapter it possesses. However, all hosts
on the same physical network must have the same network prefix. (For
example, Take a look at the IP addresses on the side of each machine in the
lab)
3. DYNAMIC and STATIC NAMING: IP addresses can be assigned uniquely by
the administrator or assigned dynamically by a DHCP (DOMAIN HOST
CONFIGURATION PROTOCOL) server. DHCP is a dynamic router in that it
builds and updates its own routing tables. It automates what the
administrator has to do manually. Instead of dynamically naming a unique
number for a network address, the server assigns a network address to
whoever goes on the network next. Thus the network address of a computer
or workstation will be different each time. It can also assign other things too,
as a default gateway, DNS server, WINS server, and SUBNET MASK.
4. There are really 2 addresses in the TCP/IP packet
o IP Addresses (starting address and ultimate ending address)
o MAC addresses (Stopping point along the way)
5. IP ADDRESS CLASSES: IP addresses are grouped in different classes.
Classes are allocated to organizations that request them in address blocks.
The INTERNIC assigns the addresses. Three classes are used for HOSTS.
A network is divided into subnets. A SUBNET is a network on where you are
currently located. That network can be made longer by adding more subnets.
When a network packet is not addresed to its own network or subnets, it is
forwarded to a DEFAULT GATEWAY (like a post office).
THE NUMBER OF HOSTS THAT MAY BE ALLOWED IN A NETWORK IS
DETERMINED BY CLASS: Each class uses special numbering scheme for
Domain Names.
o
Class A Addresses (very few left). Example: X.0.0.0
X = from 1 - 126. That is, 1.X.X.X - 126.X.X.X.
First octet identifies the network, i.e. 1-126; and the last three identify
the node.
CLASS A
DEFAULT SUBNET MASK = 255.0.0.0
11111111. 00000000 00000000 00000000
Network
o
node
node
node
Class B Addresses
128.0.0.X - 191.255.X.X.
The first two octets identify the network and the last two the node.
CLASS B
DEFAULT SUBNET MASK = 255.255.0.0
11111111. 11111111 00000000 00000000
Network
o
Network
node
node
Class C Addresses: 192.0.0.X - 223.255.255.X
The first three octets identify the network, and the last octet is the
node.
CLASS C
DEFAULT SUBNET MASK = 255.255.255.0
11111111. 111111111 11111111 00000000
Network
Network
Network
Network
6. PORT NUMBERS: TCP/IP has its own protocols. Different TCP/IP Internet
protocols use different port numbers to connect to web servers.
o HTTP uses default port 80 or 8080
o FTP (File Transfer Protocol) uses default port 21
o TELNET (text communication) uses default port 23
o SMNP uses default port 161
o SMTP (Simple Mail Transfer protocol) uses default port 25
7. DOMAIN NAME: Your IP address not only comes in numbers but has a
Domain Name. It is easier to remember a name than a number.
The DNS breaks addresses into groups and gives each level the responsibility
for the levels under them. Each level is called a domain. A period separates
each domain name from the next one. The right most portion of the address
identifies the top level domain name which references the organization type.
The following table lists commonly used domain names:
.com = Commercial organizations
.edu = Educational organizations
.gov = Government (non-military)
.mil = Military organizations
.org = Non-profit association
.net = Network resources
Two services that the TCP/IP protocol uses to resolve domain name to IP
adresses are
HOST FILE : a test file that is kept on the local machine and
contains a list of other hosts and IP numbers. The domain
name resolver goes to this text field first.
 DNS Server: Every company has a DNS server that
workstations may consult for a name to IP address resolution.
THE DNS server contains FQDN (Fully Qualified Domain
Names) to IP address matches. This database contains entries
for every host within the organization. Only one DNS server will
keep the master database.
 LMHosts - WINS: A LMHost file resolves a NetBIOS name to
an IP address. The file must be installed and kept up to date on
each machine. The WINS server is a database that keeps track
of IP addresses and NetBIOS names. The WINS server is
dynamic in its configuration and updates.
TROUBLESHOOTING TCP/IP UTILITIES:
 PING: The ping command is used to test connectivity to a
host. It is a loop-back address. You can also Ping an address on
the other side of your router to test the default gateway.

o
To check if you have a path to an Internet host, enter the Ping
command and the host's IP address at the command line, as in
the following example:
PING 204.32.23.67
NOTE: You can also use Ping with the DNS name of the host,
such as www.wavetech.com.

TRACERT:This utility allows you to find the route used between
you and the remote computer host. For example, say that you
are having trouble reaching a host named www.yahoo.com.
Type the following command at the command prompt:
TRACERT WWW.yahoo.com
and press enter.

WINIPCFG/IPCONFIG: A good utility to use to check the
TCP/IP configuration on a Windows 95 workstation is
WINIPCFG. You can quickly determine a computer's IP address,
subnet mask, and default gateway using this utility. Windows
NT has a command line utility, IPCONFIG that presents similar
data about the IP configuration on an NT platform.
2. IPX Network Protocol
IPX stands for Internet Packet Exchange. It is a Novell NetWare designed
transport protocol. Novell Netware is an operating system made of FAT and
DET(Directory Entry Table). Performs addressing and routing functions. Resides in
the NETWORK layer. Requires some configuration. Requires the administrator to
uniquely assign a network or cable segment address.
3. NetBIOS/NetBEUI Network Protocol
Stands for Network Bios Input Output Sustem and Network Advanced User
Interface. Microsoft designed this protocol for fast packet delivery in a small
network without much configuration. It is not routable, but operates on the
NETWORK and TRANSPORT layers of the OSI model.
NETWORK HARDWARE
More than any feature, network hardware may determine the
speed, quality and performance of a network.
Hubs
A hub is a central connecting device that joins computers in
a star configuration. Hubs may be passive or active. A passive
hub merely connects computers to the network and does not
process data in any way. Active hubs, sometimes called
repeaters, regenerate the data in order to maintain signal
strength. Some hubs have intelligence and can perform additional
duties such as bridging, routing and switching.
SWITCHES
Fast Ethernet switches allow dedicated, high-speed connections at either 10BASE-T
or 100BASE-TX. They are ideal for connecting servers or multiple hubs in small
businesses that want the highest network performance possible to exchange large
data files and images, and access real-time information. A switch does this by
providing dedicated bandwidth to every device—server, PC, or hub—connected to
one of its ports. They are intelligent in that they give priority to large
bandwidth data.
Repeater
A repeater is the simplest and least expensive of the three. Repeaters are usually
small enough to fit in your hand and are used to connect two segments of
network cable. Extends the signal and distance of the LAN. The repeater
retimes and regenerates signals but does not change the data frame or packet in any
way.
Transceiver
A tranceiver connct different Ethernet nodes together in an organized fashion, and
allows multiple Ethernet segment nodes to connect to eachother to create a
segment.
Bridge
A bridge is like a smart repeater. Bridges, like repeaters, can connect two network
segments, but bridges are a little smarter about the data they transport. Most
bridges have the capacity to listen to the network and figure out the
address of each computer on both sides of the bridge. The bridge can then
inspect each message that comes from one side and broadcast it to the
other side of the bridge, if the message is intended for a computer that is on the
other side. If the paket's destination is on the same side of the bridge, it is is
discarded. This creates a more efficient scheme for data transport. The bridge


can connect segments that use different cable media types, like
10BaseT(Twister Pair) and 10Base5(Coaxial).
cannot connect different transport protocols - like Ethernet and Token Ring
networks.
Routers
A router is like super-intelligent bridge. They can link multiple LANs and look deeper
into the data packet to determine its destination. Routers not only know the
addresses of the computers on the network but are aware of all the other
bridges and routers on the network and can decide the most efficient path
in which to send data. The router uses a routing table of network addresses to
determine where to forward the packet.When a router receives data, it discards the
outer packet or frame or MAC address, repackages the data with network address,
and retransmits the signal. By stripping off the outer layers of data before sending a
packet, the total number of bits moving across the network is reduced. The router at
the receiving end then repackages the data into a packet of frame that is appropriate
for its network. There are ROUTABLE and NON-ROUTABLE protocols.


TCP/IP and IPX/SPX are routable
NetBEUI is non-routable because it cannot work out of its own subnet.
Brouters
A brouter is like a bridge that have advanced intelligence that allows them to take on
duties that would normally require a router. These bridges are called brouters.
Gateways
A gateway is like a super-intelligent router. Gateways are designed to connect
radically different networks. Although slower than a bridge or router, a gateway
has its own processor and memory to perform complex functions such as interpreting
between computers that speak different languages through both protocol and
bandwidth conversion. A gateway can convert a TCP/IP packet to a NetWare IPX
packet and vice versa. An example of a gateway is a messaging gateway, which
converts messages between different protocols.
Keys To Remember:
Repeaters, bridges, routers and gateways all extend and segment networks. Because
of this, they’re often confused, as they may take on similar duties. The difference
between these devices lies in the different degrees of data discrimination and
handling capability.
Repeater: Regenerates signals to span longer segments of network. Does not alter
data.
Bridge: Links two subnets (networks) that use the same media and protocol. May
control data traffic and speed.
Router: Allows the interconnection of two or more physically distinct networks and
have advanced intelligence enabling it to determine the most efficient method of
delivering data.
Gateways: Designed to connect radically different networks.
FAULT TOLERANCE
Fault tolerance involves storing data on multiple hard drives to insure against the
failure of any individual drive. There are several levels of fault tolerance, referred to
as RAID (Random Array of Inexpensive Disks) levels.
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RAID Levels
FAULT TOLERANCE
RAID Levels