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MOCK LECTURE in
COMPUTER NETWORKS TRANSMISSION MEDIA
TOPICS COVEREDA. Transmission Medium1. Definition
2. Categories of Transmission Medium
3. Twisted Pair Cable
4. Types of Twisted Pair Cable
5. Categories of Unshielded Twisted Pair Cable
B. Data Transmission Devices
C. ANSI/EIA/TIA/568 Cabling Standards
1. 568A
2. 568B
3. Straight-through Cable
4. Cross-Over Cable
A. TRANSMISSION MEDIUM
TRANSMISSION MEDIUM
These are the different types of transmission channels including free-space or wireless RF transmission, metallic cable, and optical fiber cables which carry and transmits data.
TWO CATEGORIES OF
TRANSMISSION MEDIUM
1. PHYSICAL OR CONDUCTIVE MEDIUM
Also known as GUIDED TRANSMISSION MEDIUMGuided Transmission Media uses a cabling system that
guides the data signals along a specific path. The data signals are bound by the cabling system.
2. RADIATED OR WIRELESS MEDIUM
Also known as UNGUIDED TRANSMISSION MEDIUM Unguided Transmission Media consists of a means for the
data signals to travel but nothing to guide them along a specific path. The data signals are not bound to a cabling system.
Examples of wireless medium is the air or space in which data is transmitted in the form of radio waves.
TWISTED PAIR CABLE
A type of physical medium which is packaged in two or more pairs of single conductor copper wires that have been twisted around each other.
The twisting of the wire is done to reduce the amount of noise or interference one wire can inflict on the other.
Each single conductor wire is encased within plastic insulation and cabled within one outer jacket.
TWO TYPES OF TWISTED PAIR CABLE
1. UNSHIELDED TWISTED PAIR (UTP)
Twisted pair cables without shield are called Unshielded Twisted Pair and commonly abbreviated UTP usually used for Ethernet applications uses the RJ line of connectors.
2. SHIELDED TWISTED PAIR (STP)
Twisted pair cables with a shield are called Shielded Twisted Pair and commonly abbreviated ST usually used for IBM Cabling system and requires a specific and custom connector.
CATEGORIES OF
UNSHIELDED TWISTED PAIR CABLE
1. CATEGORY 1 (CAT 1)
Standard telephone wire designed to carry analog voice or digital data at low speed.
Not recommended for transmitting megabits of computer data.
2. CATEGORY 2 (CAT 2)
Higher quality telephone wire than Cat 1 producing less noise and signal attenuation.
Usually found on T-1 SYSTEMS (T-1 is the digital telephone circuit that transmit voice or data at 1.544 Mbps) and ISDN (Integrated Services Digital Network, a newer digital telephone circuit that can transmit voice or data or both from 64 kbps to 1.544 Mbps.
3. CATEGORY 3 (CAT 3)
Designed to transmit 10 Mbps of data over a local area network for distances up to 100 meters.
Much of today’s CAT 3 wires are used in telephone circuits rather than LANs.
4. CATEGORY 4 (CAT 4)
Designed to transmit 20 Mbps of data over a local area network for distances up to 100 meters.
5. CATEGORY 5 (CAT 5)
Designed to transmit 100 Mbps of data for a 100 MHz signal over a local area network for distances up to 100 meters.
It has higher number of twists per inch and is manufactured with higher quality materials than Cat 1 to Cat 4 to introduce less noise.
6. CATEGORY 5e (CAT 5e)
Designed to transmit up to 250 Mbps of data pair at 125 MHz signal over a local area network for distances up to 100 meters.
7 . CATEGORY 6 (CAT 6)
Designed to transmit up to 250 Mbps of data pair at 200 MHz signal over a local area network for distances up to 100 meters.
8. CATEGORY 7 (CAT 7)
A UTP wire just beginning to appear in Europe and North America and is not officially approved as a standard as of 2005.
It is designed to support up to 600 MHz signal bandwidth for100 meters.
B. DATA TRANSMISSION DEVICES
1. HUB
Act as junction boxes, linking cables from several computers on a network
Usually sold with 4, 8, 16 or 24 portsMay allow connection of more than one kind of cabling,
such as UTP and coax.Repeat (reconstruct and strengthen) transmitted signals
Important since all signals become weaker with distance
Extends the maximum LAN segment distance
HUB
2. SWITCH
Looks similar to a hub, but very different inside and does not have the capability to reconstruct and strengthen transmitted data signals like a hub.
Designed to support a small set of computers (16 to 24) in one LAN.
Designed to support a group of point-to-point circuits but no sharing of circuits.
DIFFERENCE BETWEEN A HUB AND A SWITCH
Switch reads destination address of the frame and only sends it to the corresponding port while a hub broadcasts frames to all ports.
Switches vs. HubsSwitches vs. Hubs
http://www.starlancs.com/EducateMe/educate_network_switch.html
3. ROUTER
It is an electronic device that is used to forward data between computer networks.
In a local area network, the router is the device responsible for connecting the workstations into the internet.
4. MODEM
It is a device used to convert a form of electrical signal into digital information that can be transmitted easily between network and data transmission devices and decode the transmitted data easily to reproduce the original transmitted data.
http://us.bestgraph.com/gifs/modems-1.html
5. WIRELESS ACCESS POINT
It is a device that allows wireless devices to connect to a wired network using Wi-Fi Bluetooth or related technology.
WIRELESS NETWORK
It refers to any type of computer network that is not connected by cables of any kind.
C. ANSI/EIA/TIA/568 CABLING STANDARD
ANSI/EIA/TIA 568
The EIA/TIA/ANSI Commercial Building Wiring Standard also known as the Structured Cabling Standard
It is the standard that specifies cable physical attributes and performance characteristics which is the basis for Cat 5 cable wiring scheme.
The pin designations for Cat5 cable is defined in EIA/TIA-568A and EIA/TIA-568B.
568A is the original standard which later is updated by 568B. The difference between 568A and 568B wiring scheme is on
pins 1, 2, 3, and 6. The approximate maximum cable length for this standard is
100 meters.
STRAIGHT-THROUGH CABLE
Is a Cat 5 cable that has similar wiring in both ends. Both cable ends follow either 568A or 568B. If you buy a Cat 5 cable, a practical way to check if it is a straight-through cable is by laying the two ends (connectors) side by side and verifying the colors order. If the colors in both ends are in the same order, it is a straight-trough cable. A straight-through cable is used to connect a computer to a hub or a switch.
CROSSOVER CABLE
Is a Cat 5 cable that has one end following 568A and the other 568B. A crossover cable is used to connect two computers directly, that's without a hub or a switch. However some computer models have auto-crossover (a.k.a. auto-switching or auto-MDI/MDIX) port that lets a computer connect directly to another computer using a straight-through cable.
Crossover Cable Wiring 568A on one end, 568B on the other end. Pins 1, 2, 3, 6 of 568A are crossed to pins 3, 6, 1, 2 of 568B.
1. GRADED RECITATION An after-lecture computerized graded recitation will
immediately commence after the lecture to assess the learning progress of the learner.
2. WRITTEN EXAMINATION A written examination about the topic Computer Networks and
Transmission Media will be given to the learner a day after the discussion.
3. PRACTICAL EXAMINATION A practical examination on how to terminate a Straight-
Through Cable and Cross-over Cable will be administered to assess the learner’s practical ability to apply what has been learned in the lecture.
LEARNING ASSESSMENT TOOLS
GRADED RECITATION
Students will be called one by one, and a computer application program will randomly display one particular question for the student to answer. The question will be displayed for five (5) seconds and a 10-second timer will start to tick, giving the student the chance to give the answer to the displayed question within the given timeframe. Students who will be able to answer correctly will earn points/percentage that will be computed as part of their grade in the recitation.
A video sample of the screenshots of the computerized graded recitation for the student is shown on the next slide
WRITTEN EXAMINATION
Students will be a given an objective type written questionnaire to answer within a specified timeframe as part of the learning assessment.
Objective type of questions such as identification, matching type, True or False, critical thinking questions, short essay writing, and the like will be the content of the written examination (see sample written exam).
PRACTICAL EXAMINATION
A Laboratory Manual/Handouts providing the step-by-step procedures in terminating a Straight-Through Cable be provided to the students (See next slides).
Students will be given a definite period of time to complete the given laboratory activity and will be graded according to the specific rubric intended for the evaluation of the said practical examination (click the link below to see the sample practical exam).
RUBRIC FOR EVALUATION AND GRADING OF LABORATORY ACTIVITY
OBJECTIVE/CRITERIA PERFORMANCE INDICATORS
UNSATISFACTORY SATISFACTORY GOOD EXCELLENT
SPEED (25 POINTS)
( 0 POINTS)Student finish the laboratory activity exceeding
the 45-minute period
(15 POINTS)Student finish the laboratory activity within
30-minute period
(20 POINTS)Student finish the laboratory activity
within 20-minute period
(25 POINTS)Student finish the laboratory activity
within 15-minute period
INTACT RJ-45 CONNECTOR(10 POINTS)
( 0 POINTS)RJ-45 connector shows broken lock, broken cable retainer, and pins not properly crimped
(6 POINTS)RJ-45 connector shows broken cable
retainer only
(8 POINTS)RJ-45 connector shows broken lock only
(10 POINTS)RJ-45 connector shows no broken lock, no broken cable retainer, and
pins are properly crimped
CABLE JACKET AND CABLE RETAINER PROPER CONNECTION
(10 POINTS)
( 0 POINTS)RJ-45 connector cable retainer is broken,
letting the cable jacket slip out of the connector when pulled
(8 POINTS)RJ-45 connector cable retainer is not
broken but cable jacket slips out of the connector when pulled
(10 POINTS)RJ-45 connector cable retainer is not broken and cable jacket do not slips
out of the connector when pulled
CORRECT ANSI/EIA/TIA 568-B STRAIGHT TROUGH
CONFIGURATION(30 POINTS)
( 0 POINTS)ANSI/EIA/TIA 568-B color coding standard is
followed
(30 POINTS)ANSI/EIA/TIA 568-B color coding
standard is not followed
CABLE CONNECTIVITY(25 POINTS)
( 0 POINTS)LAN Cable tester do
not show proper indication of UTP cable connectivity
(25 POINTS)LAN Cable tester
show proper indication of UTP cable connectivity
