Networking quiz 2

What is the WO, and what is its purpose?

(WO) Workstation or Work Area Outlet - Also called the TO (Telecommunications Outlet), it's used to connect devices to the cable plant. The cable type typically used is CAT3, CAT5, CAT5e, CAT6, CAT6A, and various coaxial cables. Devices typically connected to these outlets are PCs, printers, servers, phones, televisions, and wireless access points.

What is the data rate for Ethernet?

10 Mbps

What is the overall length limitation of an individual cable run from the telecommunications closet to a networking device in the work area?

100 meters

What is the data rate for gigabit Ethernet?

1000Mbps (802.3z)

How many wire pairs are in a CAT6 twisted-pair cable?

4

What is the length of pair 7-8?

46ft is the length for these pairs

What is the length of pair 4-5?

72ft is the length for these pairs

How many pins does an RJ-45 modular plug have?

8

How many wires are in a CAT6 twisted-pair cable?

8

A general rule of thumb is to allow how many meters for the cable run from the telecommunications closet to the work area?

90 Meters

What is a cross-connect?

A space where you are going to take one or multiple cables and connect them to one or more cables or equipment.

Define Alien Crosstalk and draw a picture of how this can happen.

Alien Crosstalk - unwanted signal coupling from one permanent link to another.

Which subsystem does permanent networking cabling within a building belong to?

Backbone Cabling

What is a benefit of using shielded twisted-pair cabling?

Cable with the addition of a shield is called shielded twisted-pair (STP) cable. The addition of this shield reduces the potential for electromagnetic interference (EMI) as long as the shield is grounded.

Define a UTP full channel test.

Consists of all the link elements from the hub or switch to the wall plate

Define a UTP link test.

Defines the point from one cable termination to another

Define margin (dB) relative to cable measurements. What does it mean if the margin lists a negative value?

Each cabling standard has specific channel specifications that are used as guidelines for use in a network. Each parameter has a set margin (dB) that is used to make sure the cable can handle the traffic being sent on it. If the margin lists a negative value the test fails.

The Telco and the ISP usually connect to what room in the campus network hierarchy?

Equipment Room

What is F/UTP, and what is its purpose?

F/UTP - Foil Twisted Pair a. There are several advantages to using a shielded cable. The first is that a shielded cable offers better security because there is less chance that the data will radiate outside the cable. Additionally, the foil shield helps improve noise immunity from Electro-Magnetic Interference (EMI), Radio Frequency Interference (RFI), and most importantly, AXT.

Why did this cable fail the test?

Failure due to termination problem

Why is delay skew critical?

It is critical in high-speed data transmission that the data on the wire pair arrive at the other end at the same time.

The expected attenuation loss of a 20m UTP cable should be (greater or less than) a 90m UTP cable?

Less Than

What is the main cross-connect?

Main Cross-Connect (MC) - Usually connects two or more buildings and is typically the central telecommunications connection point for a campus or building. It is also called the Main Distribution Frame (MDF) or Main Equipment Room. The MC connects to telco, an ISP, and so on. Another term for the MC is the campus distributor. (CD)

Define the term NEXT and what it measures.

NEXT (Near-end Crosstalk- A measure of the level of crosstalk or signal coupling within the cable, with a high NEXT (dB) value being desirable.

Signals travel in a cable at some percentage of the velocity of light. The term of this is?

Nominal Velocity of Propagation (NVP) ( NVP is some percentage of the velocity of light and is dependent on the type of cable being tested. )

Define Power-Sum measurements.

Power-Sum testing measures the total crosstalk of all cable pairs. (This test ensures that the cable can carry data traffic on all four pairs at the same time with minimal interference. )

What is 8P8C, and what connector type is most associated with this?

Stands for 8-pin 8-conductors and is defined by ANSI/TIA-968-A and B but is commonly called RJ-45 by both professionals and end users.

Why are power-sum measurements critical for high-speed data communication over UTP?

The gigabit data rate capability of twisted-pair requires the use of all four wire pairs in the calbe, with each pair handling 250Mbps of data. (4x250Mbps = 1Gbps) Hence the need to obtain the combine performance measurements of all four wire pairs. ( Power sum measurements provide a measure of the total crosstalk of all cable pairs, ensuring that the cable can simultaneously carry data traffic on all four wire pairs with minimal interference. )

What is the limit on the bend radius for a UTP cable, and why is this important?

The limit on the bend radius is four times the outer jacket diameter. The reason for this is bends exceeding the limit can introduce attenuation loss.

What is the difference between T568A and T568B?

They are just two different manufacturer standards used to wire the modular connector hardware. a. There is no performance improvement with either, just a color order choice. b. Industry tends to favor T568A wiring order; however, either order can be used as long as the order is maintained throughout the network.

Define propagation delay.

This is a measure of the amount of time it takes for a signal to propagate from one end of the cable to the other.

What does an "X" on the input to a hub represent?

This means that transmit and receive pairs are internally swapped to maintain proper signal alignment of the TX and RX pairs. Even if the "X" is missing, the switch or hub still properly aligns the TX and RX wire pairs.

What is the purpose of a lacing tool?

To match the wire colors to the proper order (T568A/T568B) displayed on the sides of the lacing tool.

Define the term cross-connected input.

Transmit and receive pairs are swapped to maintain proper signal alignment of the TX and RX pairs.

A NEXT measurement of 59.5 dB is made on wire pairs 1-2/3-6. A next measurement of 51.8db is made on wire pairs 3-6/7-8. Which cable pairs have the best measure NEXT performance?

Wire pairs 1-2/3-6 (A high NEXT (dB) value is desirable.

Is a high PSNEXT measurement desirable?

Yes because it indicates better cable performance.

The patch cable from a computer typically terminates into which of the following? a. Jack in a wall plate b. BNC connector c. Thin net d. Rl-l l modular plug e. RG-59

a. Jack in a wall plate

Identify the six subsystems of a structured cabling system.

i. Building Entrance (Also called (EF) Entrance Facilities) ii. Equipment Room (ER) iii. Telecommunications Closet (Also called (TR) Telecommunications Room or (TE) Telecommunications Enclosure) iv. Backbone Cabling v. Horizontal Cabling vi. Work Area

What is the difference in CAT 5 and CAT 5e?

i. CAT 5 - Up to 100MHz/100Mbps, 100-m length ii. CAT 5e - 100MHz/1000Mbps (Applications with improved noise performance in a full duplex mode.

What improvements will CAT6 and CAT7 cable provide?

i. CAT6- Can support 10-Gbps data rates but over a distance less than 55 meters. ii. CAT6a Supports 10-Gbps data rates up to 100 meters iii. CAT7-support 10-Gbps up to 100 meters with improved bandwidth.

What doe EIA and TIA stand for?

i. EIA - Electronics Industries Alliance ii. TIA - Telecommunications Industry Association

What are the three parts of the EIA/TIA 568-B standard?

i. EIA/TIA-568-B.1: Commercial Cabling Standard, Master Document ii. EIA/TIA-568-B.2: Twisted-pair Media iii. EIA/TIA-568-B.3: Optical Fiber Cabling Standard

Which cable, UTP or STP, is preferred by the industry?

i. Industry testing on STP cable has shown that the addition of a shield does increase the usable bandwidth of the cable by increasing the noise rejection between each of the wire pairs. However, the tests have shown that there is not a significant advantage of placing a shield over a properly installed 4pair 100-ohm UTP cable. ii. Most manufacturers are recommending the use of UTP cable for cabling computer networks except for very noisy environments.

Why is balance an issue in UTP cables, and what is TCL?

i. The balance or symmetry of the signal over the wire pairs helps minimize unwanted leakage of the signal. ii. TCL - Transverse Conversion Loss - The TCL measurement is obtained by applying a common-mode signal to the input and measuring the differential signal level on the output. ( TCL is sometimes called LCL (Longitudinal Conversion Loss). The ELTCLT value (expressed in dB) is the difference between the TCTL and the differential mode insertion loss of the pair being measured. TCTL is the loss from a balanced signal at the near-end to the unbalanced signal at the far end. )

What is the difference between "straight" and "cross-connected" input ports?

i. The four wire pairs connect to the same pins number on each end of the cable. ii. Cross-Connected - The transmit pair of device A connects to the receive pair on device B, and the transmit pair of B connects to the receive pair of A.