Chapter 3 Flashcards
Name two types of cables used in today’s networks
Twisted pair, fiber optic.
What are coaxial cables used for?
Coaxial cables are primarily used to transmit high-frequency signals, most commonly for distributing cable television signals, connecting to internet service providers (ISPs), and carrying data in computer networks, particularly where high bandwidth and signal quality are required, due to their excellent shielding capabilities and ability to transmit data over long distances with minimal signal loss.
Name the type of end used for Coax
BNC (Bayonet Neill-Concelman)
Name the type of end used for twisted-pair
RJ-11 for voice, RJ-45 for data
Which pins aren’t used in 568A or 568B standard?
In both the TIA/EIA-568A and TIA/EIA-568B standards, pins 4, 5, 7, and 8 are not used for standard 10/100 Mbps Ethernet (10Base-T and 100Base-TX). These pins are reserved in the cable but become active in Gigabit Ethernet (1000Base-T), where all four pairs are utilized.
ST (in networking)
In networking, ST stands for Straight Tip, a type of fiber optic connector. It features a bayonet-style twist-lock mechanism, ensuring a secure connection. ST connectors are commonly used in multimode fiber networks, such as campus backbones and enterprise networks.
SC (In networking)
Subscriber Connector (SC) or Square Connector (SC) is a fiber optic connectors with a push-pull locking mechanism. It is widely used in single-mode and multimode fiber networks due to its low insertion loss, durability, and ease of use. SC connectors are common in telecommunications, data centers, and fiber-to-the-home (FTTH) applications.
Name the two most popular versions of the small form factor fiber-optic connectors (SFF)
Mechanical Transfer Registered Jack (MT-RJ), Local Connector (LC)
Why would you need a T1 crossover cable?
To connect two CSU/DSUs (Channel Service Unit/Data Service Unit) directly, you would use a crossover serial cable, such as a T1 crossover cable (RJ48C) for T1 lines or a V.35 crossover cable for older serial connections. This setup enables direct communication between the CSU/DSUs without a service provider.
A CSU/DSU is a Layer 1 (Physical Layer) device in the OSI model. It converts digital signals between a network router and a leased line (such as a T1 or E1 circuit), ensuring compatibility and signal integrity over the carrier’s infrastructure. Since it does not perform routing or switching, it operates purely at the Physical Layer, transmitting raw bits without interpreting data at higher layers.
What pins connect to what pins in a straight-through cable?
1->1, 2->2, 3->3, 6->6
Picture of ST
ST
Picture of SC
SC
Picture of LC Fiber-Optic
LC Fiber-Optic
Picture of MT-RJ
MT-RJ
Most widely used fiber-optic connectors
Straight-tip (ST)
LC
Local Connector
MT-RJ / MTRJ
Mechanical Transfer Registered Jack
Name the media converters available
single mode fiber to Ethernet, multimode fiber to Ethernet, fiber to coaxial, and single mode to multimode fiber.
What is a 568A to 568A cable?
Straight-through cable. Connects hosts to switches or hubs
What is a 568A to 568B cable?
Crossover cable. Connects switches to switches, hosts directly to hosts.
CSU/DSU
A Modem. Channel service unit/data service unit
Describe a T1 crossover cable
568B crossover that connects pins 1, 2, 4, and 5 to 4, 5, 1, and 2, respectively.
Describe why you need a T1 crossover cable vs T1 straight through cable.
- Use a T1 straight-through cable to connect a router to a CSU/DSU or a service provider.
- Use a T1 crossover cable to directly connect two T1 interfaces without intermediary hardware.
Describe the operation of Broadband over Power Line
BPL allows for the transmission of data over existing power lines, both for networking home computers and for receiving Internet access to a building.
How many lines and twisted pairs are there in the 568A and 568B standards
8 lines divided into 4 twisted pairs
When would you use a straight-through cable?
connect a host to switch/hub, connect a router to a switch/hub
When would you use a crossover cable?
Switch to switch, hub to hub, host to host, router to direct host
Which pairs and colors are swapped between 568A and 568B standards
Pairs 2 and 3 (orange and green)
Which UTP wiring uses four twisted wire pairs (eight wires) and is rated for 250MHz?
Cat 6 UTP
The point at which the operational control or ownership changes from your company to a service provider is referred to as ___________________.
Demarc (Short for Demarcation), or point of demarc
Which type of cable will you use to connect switches?
Crossover cable
Which RG rating of coax is used for cable modems?
RG-6
Which UTP uses four twisted wire pairs (eight wires), is rated for 100MHz, and is
capable of handling the disturbance on each pair caused by transmitting on all four
pairs at the same time?
Cat 5e
You want to connect a host to a switch port. What type of Ethernet cable will you use?
Straight through
In what instance would you use T1 crossover cable?
When you want to connect two CSU/DSUs
568A uses which pins to make a connection?
1, 2, 3, 6
568B uses which pins to make a connection?
1, 2, 3, 6 (Remember: 1 to 3, 2 to 6)
What are two advantages of fiber-optic cabling?
It’s completely immune to EMI and RFI., It can transmit up to 40 kilometers (about 25 miles).
What are the disadvantages of fiber-optic cabling?
Difficult to install, more expensive than twisted pair, troubleshooting equipment is more expensive than twisted pair troubleshooting equipment, harder to troubleshoot
Describe Cat 1
2 twisted pairs (4 wires), 1Mhz. Pre-1983, standard for phones sys (POTS) in US
Describe Cat 2
4 twisted pairs (8 wires), 10Mhz. 4Mbps. Obsolete
Describe Cat 3
4 twisted pairs (8 wires), 16Mhz. 10Mbps. Used in ’80s. Now limited to POTS
Describe Cat 4
4 twisted pairs (8 wires), 20Mhz. 16Mbps. Applications include Token Ring networks
Describe Cat 5
4 twisted pairs (8 wires), 100Mhz. 100Mbps. Most common on current LANS.
Describe Cat 5e
4 twisted pairs (8 wires), 100Mhz. Can handle crosstalk caused by sending data on all pairs at once, making it capable of 1Gbps. Modern standard: No LAN should be set up without 5e or higher.
Desribe Cat 6
4 twisted pairs (8 wires), 250Mhz. 10Gbps. Became a standard in ‘02. Shorter max distance than Cat6a
Describe Cat 6a
4 twisted pairs (8 wires), 500Mhz. 10Gbps. 100 Meters max distance. 100% increase in near-end crosstalk (NEXT) noise reduction using ISO/IEC component specifications
What is a demarc extension?
The point after the demarc but before the line reachees your property/office – the line running from the demarc to an office floor, for example
Which RG rating is used for Thinnet
RG-58 a/u
Which RG rating is used for Thicknet
RG-8
Which RG rating is used for cable TV?
RG-59 and RG-6
Which RG raiting is used for cable modems?
RG-6
Which RG rating was used for ARCnet
RG-62
EMI
Electromagnetic interference - Interference caused by magents, lights, etc
RFI
Radio frequency interference - Interference caused by radio signals
Which UTP wiring uses four twisted wire pairs (eight wires) and is rated for 250MHz?
Category 6
The point at which the operational control or ownership changes from your company
to a service provider is referred to as ___________________.
Demarcation point or demarc
Which type of cable will you use to connect switches?
Crossover
Which RG rating of coax is used for cable modems?
RG-6
Which UTP uses four twisted wire pairs (eight wires), is rated for 100MHz, and is
capable of handling the disturbance on each pair caused by transmitting on all four
pairs at the same time?
Category 5e
What is a CSU/DSU?
A CSU/DSU is a Layer 1 (Physical Layer) device in the OSI model. It converts digital signals between a network router and a leased line (such as a T1 or E1 circuit), ensuring compatibility and signal integrity over the carrier’s infrastructure. Since it does not perform routing or switching, it operates purely at the Physical Layer, transmitting raw bits without interpreting data at higher layers.
The main differences between straight-through and crossover cables
The main differences between straight-through and crossover cables are:
1. Wiring Configuration
• Straight-through: Both ends of the cable have the same pin configuration (T568A-T568A or T568B-T568B).
• Crossover: The transmit (TX) and receive (RX) wires are swapped at one end (T568A on one end, T568B on the other).
2. Usage
• Straight-through: Used to connect different device types, such as a PC to a switch or a router to a modem.
• Crossover: Used to connect similar devices, such as PC-to-PC or switch-to-switch (without auto-MDI/MDIX support).
3. Color Coding
• Straight-through: The wire colors are identical on both ends.
• Crossover: The green and orange wire pairs are swapped at one end.
4. Common Application
• Straight-through: The most commonly used Ethernet cable type for modern networks.
• Crossover: Less common now due to auto-MDI/MDIX, which automatically adjusts for correct pin connections.
568A 568B diagrams
What is framing?
Framing in the Data Link Layer (Layer 2) is the process of encapsulating network layer data into a structured format before transmission. It defines start and end boundaries for data, ensuring that the receiving device can correctly interpret the transmitted bits.
