From the technology with which Alexander Graham Bell yelled, “Mr. Watson, come here!” to crank, dial and touch-tone phones and continuing with Ethernet from 10 million bits per second to 10 billion, a pair of copper wires has been the mainstay of communications. Needless to say, some serious technical development was required to get to today’s cables. How well do you know the path that communications copper wire has taken? Correct answers and explanations are in red text.
1. Plain old telephone service (POTS) could be easily transmitted over almost any pair of copper wires because _________.
A. It used current loop transmission technique
B. It only needed 300-3,000 Hertz bandwidth
C. Both A and B
D. Neither A nor B
Analog telephone signals (POTS) use a current loop over a frequency range of 300-3000 Hz.
2. One of the first uses of twisted-pair cables for computer networking was IBM Type 1 cable for token ring
networks, which was a(n) _________.
A. Unshielded twisted-pair cable with 150 ohm (?) impedance
B. Shielded twisted-pair cable with 150 ohm (?) impedance
C. Unshielded twisted-pair cable with 100 ohm (?) impedance
D. Shielded twisted-pair cable with 100 ohm (?) impedance
IBM Token Ring used a shielded two pair cable of 150 Ω impedance that was included in TIA-568 and TIA-568-A.
3. Anixter, a datacom distributor,
first tested and graded cables for data usage, with its _________ cable supporting 10 megabit Ethernet,
also called 10Base-T.
A. Level 1
B. Level 2
C. Level 3
D. Level 4
Anixter called their tested cables “Levels," starting with Level 1 for POTS. Level 3 was required for 10base-T.
4. TIA used Anixter’s levels program as a model when the association began standardizing structured cabling for premises applications, but it called its cable ratings _________.
A. TIA Levels
TIA-568 chose the name “Category” for their cable rating system which was loosely based on the Anixter Levels program.
5. TIA standardized one cable type for 16 mbps Ethernet, but it became obsolete in a few months by a higher performance cable. What was it?
A. Category 3
B. Category 4
C. Category 5
D. Category 5a
Category 4 was an upgrade of Cat 3 for 16 Mb Token Ring, but both were made obsolete by Fast Ethernet at 100 Mb/s on Cat 5.
6. Most cable plant rating developments have been driven by faster network speeds standardized by the IEEE
Ethernet committee (IEEE 802.3), with one exception. What was it?
A. Category 5
B. Category 5e
C. Category 6
D. Category 6a
The TIA created Cat 6 hoping for simpler transceivers for Gigabit Ethernet, which never materialized.
7. Category _________ cable was
developed to transmit fast Ethernet (100 mbps) signals.
Cat 5, rated to 100 MHz, was developed for the universally accepted version of fast Ethernet, called 100base-TX.
8. Enhanced Category 5 (Cat 5e) required new specifications and testing because gigabit Ethernet (1,000Base-T) _________.
A. Transmitted on all four pairs in both directions
B. Transmitted on all four pairs in the cable
C. Transmitted in both directions
D. Exceeded the frequency rating of Cat 5
Gigabit Ethernet (1000base-T) required using all four pairs simultaneously in both directions, requiring new standards for the cabling.
9. FCC no longer allows two-pair POTS wiring in homes, requiring as a minimum a cable rated _________.
A. Category 3
B. Category 5
C. Category 5e
D. Category 6
FCC now requires Cat 3 but most homebuilders use Cat 5 as it is not much more expensive.
10. In March 2008, TIA approved
standards for _________ with many new specifications to allow use of 10 gigabit Ethernet over 100 meters.
A. Category 6
B. Enhanced Category 6
C. Extended Category 6
D. Augmented Category 6
10G Ethernet required higher performance cable, which during its 5 year development cycle was called several names by vendors until the standards committee settled on “Augmented Cat 6.”
HAYES is a VDV writer and educator and the president of The Fiber Optic Association. Find him at www.jimhayes.com.