Lesson 1:
Access Methods …………… 108
Lesson 2: How
Networks Send Data ….. 117
Lesson 3. Ethernet ……………………… 125
Lesson 4: Token
Ring ………………..… 141
Lesson 5: Apple
Talk and ArcNet ……. . 152
CLASSROOM NOTES: MINIMUM STANDARDS FOR WINDOWS 98 UPGRADE
DX266 (486) Minimum
CPU processor
RAM must be 16MB
HD 195MB
Upgrade at least to
DOS version 5 or more, and WIN 3.1 WFW 3.11, Win95
DX266 (486) Minimum CPU Processor
WIN98 – can boot off the CD-ROM, CD Rom El-torito, is the standard
Default CMOS A and C bootable, the CD-ROM is the first choice
Create WIN98 boot disk on A:\ with Win98 Driver
If UPGRADE to the system:
Type set-up to install WIN98
but this file is only created if there is a failure.
will be in a continuous loop.
DANGER If the system dies when copying files, you can permanently
damage your Hard Drive, and the CD ROM also. Do not
rush it wait to you hear it stop working and all the lights are
off. It will do the same thing as a record player, leave a large
scratch on the Hard Drive and/or the CD-ROM.
6. Netlog.txt, set-up Networking information. If there are any errors, they will
be listed in this text file.
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EXERCISE:
1. 1.
Right Click on My Computer/Properties
2. 2. Choose General – ensure it is
registered properly, if not you will need to reinstall
|
Computer: Genuine Intel Pentium ® II Processor Intel MMX ™ Technology 256.0MG RAM System: Microsoft WIN98 4.10.1998 |
TIP Always Ground yourself before installing a Computer, Important,
you can hurt yourself, and you can also damage the Hard Drive, and
not even know it, till much later, when you start having problems.
3. Select Device Manager Network Adapter General, note NT, has no Device Manager
Very hard to work with for troubleshooting.
D-Link
DFE-538TX 10/100 Adapter
BOARD NOTES:
(review, Networking book pages 77-85)
System Configuration
Options and Settings:
1. IRQ (Interrupt Request) Setting = 10
2.
3. Base Memory Address
4. DMA (Direct Memory Access) Not many devices use it, only floppy or old sound cards
It bypasses the CPU, and goes directly to RAM. It is very slow, because it puts the CPU
into a WAIT STATE and cycles. Bogs down the system.
5. 5. Bus Mastering (DMA gone right!!!) Great king of Network type of card.
Boot-Prom – PXE regular PC’s (keyboard and monitor only, similar to the dumb
terminals used on a Mainframe system.
EXERCISE:
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Cache
Cache is a separate buffer. Note: CD –RAM takes up extra storage, it is not such a
problem in this day and age with lots of storage, but years ago it would take up almost
all available memory. The most frequently used commands are stored in RAM, it usually uses
up 1.2MG of RAM.
File/System/Properties (Removable disk buffer)
Trouble Shooting – backward compatability, do not click on these, or it will return to
16-bit mode and work very slowly.
Advanced Graphic Setting: Leave as is, fine.
Virtual Memory:
Swap File (WIN98 SWP)
A Swap file manages your RAM or Virtual Memory, and you NEVER turn it off.
· will be on Hard Drive, note only $15.00 for 128 MG.
· Let WIN98 use default settings
· Move swap file size min/max. same, loose HD space forever.
·
Move swap file onto not
========================================================================
*** CHAPTER 3 ***
INTRODUCTION
In this chapter, we explore the three principal methods used to access the wires. The first method, called
contention, is based on the principle of “first come, first served,” or CSMA/CD, and CSMA/CA.
The second method, token passing, is based on the principle of waiting to take turns, which is Token Passing.
The third method, demand priority is relatively new and is based on prioritizing access to the network.
Access Methods (p 108)
In Networking, to access a resource is to be able to use that resource. This lesson introduces the role
of access methods in putting data on a network cable. It focuses on three major access methods:
carrier-sense, multiple-access methods, token passing, and demand priority.
Traffic Control on the Cable
The set of rules that defines how a computer puts data onto the network cable and takes data from the
cable is called access method. It helps to regulate the flow of the data, in quite the same way as a
traffic light. The access methods need to be consistent in the way they handle the data.
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Carrier-Sense Multiple Access with Collision Detection
(CSMA/CD)
CSMA/CD, each computer on the network including the clients and servers, checks the cable for
network traffic. The NIC card listens to the wire to see if there is no traffic, if not it sends out its
signal of data. Remember if two or more computers send data at the same time, there will be a
data collision. When this happens all the data is destroyed, and it must be individually retransmitted.
Each computer determines its own waiting period, which will reduce the chances of another collision.
It is important that each end of the cable are properly terminated with terminators, or the signals will
bounce from end to end. Also, they should be grounded at one end, but not both, or you will have
a continuous loop. This is a common and popular method, and it is a method of contention, because
there is constant fighting to send data.
Carrier-Sense Multiple Access with Collision Avoidance
(CSMA/CA)
CSMA/CA, is the least popular of the three methods. In CSMA/CA each computer signals its
intent to transmit before it actually transmits data.
Apple computer uses a built-in operations system already on their computers when you purchased
them. It was called Apple-Talk, but this system was unique to MacIntosh only, which is dumb.
This is also a contention method, computers are fighting for access to the data line. CSMA/CA
looks at the time and prioritizes inside the packet, therefore the packet was larger and more
cumbersome to transmit
Only peer-to-peer installed on computer when you bought it. Very costly, most computers at that
time were $5,000.00, but Mac’s were close to $12,000.00
Token Passing
The Token
with the data stream is the only thing moving around the cable. It is
Fault tolerant redundancy, may need an extra Hard Drive, in case the current drive Crashes. The
data is transmitted in frames, additional information such as addressing, headers and trailers are
attached. The token always has complete control of the data line, therefore making this method a
method of non-contention.
A Beacon, keeps telling which machine is working. Works well in a trouble-shooting atmosphere.
Token Passing is faster than CMSA/CD if traffic is heavy. The token has complete control
over the cable, so it can send continuous requests and demand very quickly, and there is no
worry of collisions. The token organizes who goes next. IBM holds onto this technology, and
they did not expand on it, their loss.
Demand Priority Access Method
Demand
priority access method is quite new designed for 100-Mbps
Ethernet, or 100VG-AnyLAN.
The IEEE standard is 802.12 This was developed by Hewlett Packard. It uses a smart hub,
100VG-AnyLAN. Another name for the hub is a repeater is responsible for noting addresses, links,
and end nodes and verifying that they all function properly. According to the 100VG-AnyLAN
definition, an end node can be a computer, bridge, router or switch.
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ACCESS
METHODS SUMMARY CHART:
|
Feature/Function |
CSMA/CD |
CSMA/CA |
Token Passing |
Demand Priority |
|
|
Type of Communication |
Broadcast- based |
Broadcast- based |
Token- Based |
Hub-based |
|
|
|
|||||
|
Type of Access Method |
Contention |
Contention |
Noncontention |
Contention |
|
|
Type of Network |
Ethernet |
LocalTalk |
Token Ring ArcNet |
100VG- AnyLAN |
|
Data Packet
|
header (destination address) |
header |
header |
data |
Trailer CRC |
trailer |
trailer |
Will vary with the protocols uses, Mainframes use something called
Synchronous.
Asynchronus is the most common, it is random
Internet is impossible to trace what journey each data
Packet takes from the point of leaving to the point of
getting to you.
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ETHERNET
Over the years, Ethernet has become the most popular media access method to the desktop computer
and is used in both small and large network environments. Ethernet is a nonproprietary industry standard
that has found wide acceptance by
network hardware manufacturers. It
originated in
1960’s.
Ethernet uses the feature CSMA/CD as the access method. Ethernet
has the IEEE standard
of 802.3. this baseband architecture uses a bus topology, that can transmit to 10 Mbps. Ethernet is
passive which means that it requires no power source of its own, and it needs no boosting. It will not
suffer from Attenuation. It uses cable thicket, thinnet, UTP. Ethernet Cable is 90% of the market.
|
Advantages of Ethernet |
Disadvantages of Ethernet |
|
Cheap, easy to install |
STP shielding drains the data Signal. |
Why did Companies Network way
back when?:
To Share Printers, initially, too expensive in a large company to have several hundred printers.
Ethernet Frame Format
Ethernet breaks the data down into a frame instead of a packet. A frame is a package of
information transmitted as a single unit. An Ethernet frame can be between 64 and 1518
bytes long, but the Ethernet frame itself uses at least 18 bytes; therefore, the data in an
Ethernet frame can between 46 and 1500 bytes long.
ETHERNET
Is Passive, not powered, needs no boosting, will not suffer from
Attenuation.
Topology – Linear Bus/Star Bus: A straight line, and has links off of it and a terminator
at the end to finish the connection.
Star/Bus or Concentrator: Separate links off of the main area.
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THE 10-MBPS IEEE STANDARD
This section looks at the four 10 Mbps Ethernet topologies:
10BaseT Standard
The IEEE standard of 802.3 for running 10BaseT is 10Mbps, baseband, over twisted-pair cable,
is an Ethernet network that typically uses unshielded twisted-pair (UTP) cable to connect
computers. Most networks are configured in a start pattern, but internally they us a bus signaling
system like other Ethernet configurations. The hug of a 10BaseT network serves as a
multiport repeater and often is located in a wiring closet of the building. Each computer is
located at the endpoint of a cable that is connected to the hub. The Maximum length is 100M.
A 10BaseT LAN will serve 1024 computers. 10BaseT uses cat 3,4 or 5 UTP, with
RJ-45 cable ends.
10Base2 Standard
This IEEE standard is 802.3 transmits at 10Mbps over baseband wire and can carry a signal 100M.
This type of network uses thin coaxial cable, or thinnet, which has a maximum of 185 metres.
There is a 30 computer maximum per 185 metre segment.
10Base5 Standard
The IEEE specification for this topology is 10Mbps, baseband, and 500m segments.
This topology makes use of thick coaxial cable, also known as thicknet. It generally uses a bus topology
and can support as many as 100 nodes per backbone segment. The backbone or trunk segment, is
the main cable from which tranceiver cables are connected to stations and repeaters. Don’t forget that
thicknet is very hard to bend, so it is sometimes used to run as a backbone up a large highrise building.
The maximum distance between computers is 2.5 metres.
10BaseFL Standard
The IEEE standard is for fiber-optic cable. This would accommodate long cable runs between
repeaters, such as between buildings. Maximum distance is 2000M.
100-Mbps IEEE Standards
New Ethernet standards are pushing the traditional Ethernet limits beyond the original 10 Mbps.
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100VG-AnyLAN Standard
This is new technology that combines elements of both Ethernet and Token Ring Architectures.
Originally developed by Hewlett-Packard, it is currently being refined and ratified by the IEEE 802.12
committee. A 100VG-AnyLAN network is built on a star topology in which all computer are attached
to a hub. The longest cable from the 100Base VG hub to a computer cannot exceed 250M.
100BaseX Ethernet Standard
This standard is called fast Ethernet, runs on UTP Cat5 and uses CSMA/CD in a start-wired bus
topology, similar to a 10BaseT where all cables are attached to a hub.
BNC Connector
A BNC barrel connector may be used to connect thinnet cable segments together, thus extending a
length of a cable.
The
A Thinnet network can combine as many as five cable segments connected by four repeaters, but
only three segments can have stations attached.
TOKEN RING
The Token Ring architecture was developed in the mid 1980s by IBM. Token ring specifications
are governed by the IEEE 802.5 standard. Token Ring was developed to facilitate a simple wiring
structure using twisted-pair cable
that connects a computer to the network through a wall socket. It
uses Star wired ring -topology, token passing
access method, and UTP, baseband with 802.5
specifications.
Token Ring also uses Frames as the format.
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OSI
OPEN SYSTEMS INTERCONNECTION
DOWN STACK UP
STACK
|
ALL |
APPLICATION |
AWAY |
|
PEOPLE |
PRESENTATION |
PIZZA |
|
SEEN |
SESSION |
SAUSAGE |
|
TO |
TRANSPORT |
THROW |
|
NEED |
NETWORK |
NOT |
|
DATA |
DATA LINK |
DO |
|
PROCESSING |
PHYSICAL |
PLEASE |
SYSTEM ADMINISTRATORS PLANNING
1. Needs - review needs of the user
- E-Mail requirements if any
- present system
- future system requirements
- compatability
2. Budget - present
- future
- estimate if costs more, give options for upgrades and prices, be
proactive
3. Support - is there money in the budget for ongoing support.
4. Security -
Employees must be trained well on passwords – DO NOT
SHARE PASSWORDS
5. Growth - Present, predicted future
6. Upgrades – Current Hardware, take an inventory and current cabling used.
Ask for a Map of the wiring, status of wire. For example if using Cat3, do
not use Hardware that is overkill for CAT 3 specs.
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1. 7. Training - Train Help Desk, Client users.
2. 8. Query - Users, Interview, what improvements do they want.
3. 9. Test bed - Take 8-10 knowledgable users and test the system, see if it
works.
4. 10. Software - Is current software compatable, may need to work with
Programmers.
11.Internet Access – Huge security considerations, Firewall needed.
|
Entire System Accessment Process takes 7-9 Months, and sometimes 1-1 ˝ years if it is A large company |
Password protocol
- Alphanumeric
- # characters
- Upper/Lower Case
- Eg. Gr8fouru!
- Change Login Name from “Administrator”
to John Smith – a common enough name in a company, it will go
undetected by a possible hacker.
- Never surf the Internet as the “Administrator”
Windows 98 Specifications
Suggested Standards Min
Specs
1GB Hard Drive 195 MB Hard Drive
32 MB RAM 16 MB RAM
Processor Pentium 133 Processor 486 DX/266
Dos Version 5 Dos Version 5
Methods to Install:
a. Clean Install
b. CD-ROM
c. Copy Cabinet File
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Problems on Installation:
a) Do fdisk
b) Cannot detect Hard Drive, try seemoss. C/H/S (cylinders/heads/sectors)
c) Install Bootable Disk, ensure CD ROM boots to (El-torito) standard
Won’t boot to CD-ROM
d) FDISK:
Y = FAT32 (WIN98)
N = FAT16 – NT
LBA = (large block addressing)
e) Format^c:^/s (load sys files, have bootable disk)
command.com
io.sys (unique to 95/98 WIN)
msdos.sys
Make bootable, add CD/ROM files.
f) Start-up off a: boot diskette, but now CD-ROM is not working. LAST RESORT,
Boot from DOS to CD-ROM. Copy all the Cabinet Files.
g) Set-up (Mr. Buckingham will give us a list of choices for switches)
1. 1st scan the disk for errors
2. Surface errors, a good indication the Hard Drive damaged, may die within six months.
3. Review the setuplog.txt before proceeding.
h) Detection Phase, if crashes, reboot will skip over.
i) Serial Number and Company Number.
Screen Mode (Do not exceed Refresh Mode, may blow the screen)
Default Refresh Rate = VGA 640 X 480 (16 colours)
Will work on ANY Monitor
j) Start/Program/Accessories/System Tools/System Information
Tools/Windows Rep Tools
System/Configuration/Utility
*** LUNCH ****
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HARDWARE COMPONENTS
Hardware for Token Ring Networks is centered on the hug, which houses the actual ring. A token
Ring Network can have multiple hubs. STP or UPS cabling connects the computer to the hubs; patch
cables can further extend the connections. Fiber-optic cable, is especially well suited to Token Ring
Networks. Together with repeaters, fiber-optic cable can greatly extend the range of Token Ring
Networks. Cabling is joined to the components with four kinds of connectors. Other Token Ring
hardware includes media filters, patch panels, and network interface cards.
MSAU (Multi Station Access Unit)
In a Token Ring Network the Hub is known by several names that all mean the same thing. The MSAU
or MAU or SMAU, but usually called
the MSAU.
Cables attach the individual clients and servers to the MSAU, which works like other passive hubs.
Each Ring can have up to 33 hubs. Each MSAU based network can support as many as 72 computers
that use unshielded wire or up to 260 computers that use shielded wire.
When one Token Ring is full, that is, when every port on an MSAU has a computer connected to it,
adding another ring (MSAU) can enlarge the network. MSAU repeater regenerated.
Built-in Fault Tolerance
In a pure token-passing network, a computer that fails, stops the token from continuing. This can bring
down the network. MSAU’s were designed to detect when a NIC fails, and to disconnect from
it. This procedure bypasses the failed computer so that the token can continue on.
Patch Cables
Patch cables extend the connection between a computer and a MSAU. They can also join two
MSAU’s together.
Connectors
Token Ring networks usually join cables to components with the following types of connectors:
There are a
few but Token uses these the most RJ-45
telephone connectors (8-pin) for
Type 3. The next is RJ-11 telephone connectors (4-pin), for type 3.
Repeaters
Using repeaters can increase all Token Ring cable distances. A repeater actively regenerated and
retimes the Token Ring signal to extend distances between MSAUs on the network. Using one pair
of repeaters, MSAU’s can be located up to 365 Meters apart using type 3 cable, or 730 Meters
apart using type 1 or 2 cable.
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Network Interface Cards
Token Ring NICs are available in both 4 Mbps and 16 Mbps models.
Fiber-Optic Cable
Because of the mix of data streaming (streaming is undifferentiated, byte-by-byte flow of data), high speeds,
and data traveling in one direction only, Token Ring networks are well suited to fiber-optic cable. But a waste,
you only have 16-BIT capability, wasting it on fiber-optic.
AppleTalk and ArcNet
Networking Professionals also might encounter and be required to support two other architectures.
AppleTalk and ArcNet. The AppleTalk architecture is used in the Apple Macintosh environment,
while the ArcNet architecture is used in personal computer – based environments. Since the advent
of Ethernet, the popularity of ArcNet has decreased. There are no IEEE standards associated with
AppleTalk. It has CSMA/CA built into the system, and uses STP cable.
AppleTalk uses lots of broadcasting on its devices.
Local Talk uses CSMA/CA as an access method, with
STP, but also uses fiber-optic and UTP
And also uses a peer-to-peer network.
AppleShare is the file server on an Apple Talk network. You can in tern network these networks
through the use of logical
groupings called zones.
Ethertalk allows AppleTalk network protocols to run on Ethernet coaxial cable.
TokenTalk card is an expansion card that allows Macintosh to connect to an 802.5 Token Ring
Network.
ArcNet Environment
Arcnet is a simple, inexpensive, flexible network architecture designed for workgroup-size networks.
The first ArcNet cards were shipped in 1983. ArcNet technology predates the IEEE project 802
standards, but loosely maps to the 802.4 document. An ArcNet network can have a star-but or
bus topology. ArcNet uses a token-passing access method in a star-bus topology passing data at\
2.5 Mbps. ArcNet uses RG-62, and is passive.
ArcNet+
ArcNet+ supports data transmission rates of 20 Mbps. They also use DIP switches, and do not set
with pencils.
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ETHERNET SUMMARY CHART
|
Ethernet Media |
IEEE Standard |
Max. Segment |
Cable Type |
Topology |
Distance between Computers |
|
10BaseT |
802.3 |
100m |
Cat 3,4,5 |
Star Bus |
N/A |
|
10Base2 |
802.3 |
185m |
|
Bus |
.5 metres |
|
10Base5
|
802.3 |
500m |
|
Bus |
2.5 metres |
|
10BaseFL fiber-optic |
|
2000m |
|
|
|