Chapter 3 Flash Cards - LANs

Question 1

Provide the following information about Ethernet:

1. Speed
2. Alternative Name
3. IEEE Standard
4. Cable type
5. Maximum Length.

Answer 1

1. 10 Mbps
2. 10BASE-T
3. IEEE 802.3
4. Copper
5. 100 m

Question 2

Provide the following information about Fast Ethernet:

1. Speed
2. Alternative Name
3. IEEE Standard
4. Cable type
5. Maximum Length.

Answer 2

1. 100 Mbps
2. 100BASE-TX
3. IEEE 802.3u
4. Copper
5. 100 m

Question 3

Provide the following information about Gigabit Ethernet:

1. Speed
2. Alternative Name
3. IEEE Standard
4. Cable type
5. Maximum Length.

Answer 3

1. 1000 Mbps
2. 1000BASE-T
3. IEEE 802.3ab
4. Copper
5. 100 m

Question 4

Provide the following information about Gigabit Ethernet (Fiber):

1. Speed
2. Alternative Name
3. IEEE Standard
4. Cable type
5. Maximum Length.

Answer 4

1. 1000 Mbps
2. 1000BASE-LX, 1000BASE-SX
3. IEEE 802.3z
4. Fiber
5. 550 m (SX), 5 km (LX)

Question 5

Basically, the CSMA/CD algorithm can be summarized as follows:

Answer 5

• A device that wants to send a frame waits until the LAN is silent–in other words, no frames are currently being sent–before attempting to send an electrical signal.
• If a collision still occurs, the devices that caused the collision wait a random amount of time and then try again.

Question 6

What order pinout is TIA Standard T568A?

Answer 6

1. G/W
2. Green
3. O/W
4. Blue
5. Blue/W
6. Orange
7. Brown/W
8. Brown

Question 7

What order pinout is TIA Standard T568B?

Answer 7

1. O/W
2. Orange
3. G/W
4. Blue
5. Blue/W
6. Green
7. Brown/W
8. Brown

Question 8

Explain the Ethernet Straight-Through Cable Concept

Answer 8

An Ethernet Straight-Through cable connects the wire at pin 1 on one end of the cable to pin 1 at the other end of the cable the wire at pin 2 needs to connect to pin 2 on the other end of the cable; pin 3 on one end connects to pin 3 on the other; and so on. (To create a straight-through cable, both ends of the cable use the same EIA/TIA pinout standard on each end of the cable.) A straight-through cable is used to connect dissimilar devices to one another.

Question 9

Explain the Ethernet Crossover Cable Concept

Answer 9

You swap pins 1/3 and 2/6. A crossover cable is used to connect similar devices to one another.

Question 10

Which pin pairs are used for sending and receiving for the following device?PC NICs

Answer 10

Transmit: 1/2
Receive: 3/6

Question 11

Which pin pairs are used for sending and receiving for the following device?Routers

Answer 11

Transmit: 1/2
Receive: 3/6

Question 12

Which pin pairs are used for sending and receiving for the following device?Wireless Access Point (Ethernet Interface)

Answer 12

Transmit: 1/2
Receive: 3/6

Question 13

Which pin pairs are used for sending and receiving for the following device?Networked Printers (Printers that connect directly to the LAN)

Answer 13

Transmit: 1/2
Receive: 3/6

Question 14

Which pin pairs are used for sending and receiving for the following device?Hubs

Answer 14

Transmit: 3/6
Receive: 1/2

Question 15

Which pin pairs are used for sending and receiving for the following device?Switches

Answer 15

Transmit: 3/6
Receive: 1/2

Question 16

Explain the 6 steps of CSMA/CD Logic.

Answer 16

1. A device with a frame to send listens until the Ethernet is not busy.
2. When the Ethernet is not busy, the sender(s) begin(s) sending the frame.
3. The sender(s) listen(s) to make sure that no collision occurred.
4. If a collision occurs, the devices that had been sending a frame each send a jamming signal to ensure that all stations recognize the collision.
5. After the jamming is complete, each sender randomizes a timer and waits that long before trying to resent the collided frame.
6. When each random timer expires, the process starts over with Step 1.

Question 17

Explain the structure of Unicast Ethernet Addresses

Answer 17

First Half:
Organizationally Unique Identifier (OUI)
Size: 24 bits / 6 Hex Digits (i.e. 00 60 2F)
Second Half:
Vendor Assigned (NIC Cards, Interfaces)
Size: 24 bits / 6 Hex Digits (i.e. 3A 07 BC)

Question 18

Define: MAC

Answer 18

Media Access Control. 802.3 (Ethernet) defines the MAC sub layer of IEEE Ethernet

Question 19

Define: Ethernet address, NIC address, LAN address

Answer 19

Other names often used instead of MAC address. These terms describe the 6-byte address of the LAN interface card.

Question 20

Define: Burned-in Address

Answer 20

The 6-byte address assigned by the vendor making the card.

Question 21

Define: Unicast Address

Answer 21

A term for a MAC that represents a single LAN interface.

Question 22

Define: Broadcast Address

Answer 22

An address that means “all devices that reside on this LAN right now.”

Question 23

Define: Multicast Address

Answer 23

On Ethernet, a multicast address implies some subset of all devices currently on the Ethernet LAN.

Question 24

Define: 1000BASE-T

Answer 24

A name for the IEEE Gigabit Ethernet standard that uses four-pair copper cabling, a speed of 1000 Mbps (1 Gbps), and a maximum cable length of 100 meters.

Question 25

Define: 100BASE-TX

Answer 25

A name for the IEEE Fast Ethernet standard that uses two-pair copper cabling, a speed of 100 Mbps, and a maximum cable length of 100 meters.

Question 26

Define: 10BASE-T

Answer 26

The 10 Mbps baseband Ethernet specification using two pairs of twisted-pair cabling (Categories 3,4, or 5): One pair transmits data and the other receives data. 10BASE-T, which is part of the IEEE 802.3 specification, has a distance limits of approximately 100 m (328 feet) per segment.

Question 27

Define: Crossover Cable

Answer 27

An Ethernet cable that swaps the pair used for transmission on one device to a pair used for receiving on the device on the opposite end of the cable. In 10BASE-T and 100BASE-TX networks, this cable swaps the pair at pins 1,2 to pins 3,6 on the other end of the cable, and the pair at pins 3,6 to pins 1,2 as well.

Question 28

Define: CSMA/CD

Answer 28

Carrier Sense Multiple Access Collision Detect.A media-access mechanism in which devices ready to transmit data first check the channel for a carrier. If no carrier is sensed for a specific period of time, a device can transmit. If two devices transmit at once, a collision occurs and is detected by all colliding devices. This collision subsequently delays re-transmissions from those devices for some random length of time.

Question 29

Define: Full Duplex

Answer 29

Generically, any communication in which two communicating devices can concurrently send and receive data. In Ethernet LANs, the allowance for both devices to send and receive at the same time, allowed when both devices disable their CSMA/CD logic.

Question 30

Define: Half Duplex

Answer 30

Generically, any communication in which only one device at a time can send data. In Ethernet LANs, the normal result of the CSMA/CD algorithm that enforces the rule that only one device should send at any point in time.

Question 31

Define: Hub

Answer 31

A LAN device that provides a centralized connection point for LAN cabling, repeating any received electrical signal out all other ports, thereby creating a logical bus. Hubs do not interpret the electrical signals as a frame of bits, so hubs are considered to be Layer 1 devices.

Question 32

Define: Pinout

Answer 32

The documentation and implementation of which wires inside a cable connect to each pin position in any connector.

Question 33

Define: Protocol Type Field

Answer 33

A field in a LAN header that identifies the type of header that follows the LAN header. Includes the DIX Ethernet Type field, the IEEE 802.2 DSAP field and the SNAP protocol Type Field.

Question 34

Define: Shared Ethernet

Answer 34

An Ethernet that uses a hub, or even the original coaxial cabling, which results in the devices having to take turns sending data, sharing the available bandwidth.

Question 35

Define: Straight-through Cable

Answer 35

In Ethernet, a cable that connects the wire on pin 1 on one end of the cable to pin 1 on the other end of the cable, pin 2 on one end to pin 2 on the other end, and so on.

Question 36

Define: Switch

Answer 36

A network device that filters, forwards, and floods Ethernet frames based on the destination address for each frame.

Question 37

Define: Switched Ethernet

Answer 37

An Ethernet that uses a switch, and particularly not a hub, so that the devices connected to one switch port do not have to contend to use the bandwidth available on another port. This term contrasts with shared Ethernet, in which the devices must share bandwidth, whereas switched Ethernet provides much more capacity, as the devices do not have to share the available bandwidth.

Question 38

Define: Twisted Pair

Answer 38

Transmission medium consisting of two insulated wires, with the wires twisted around each other in a spiral. An electrical circuit flows over the wire pair, with the current in opposite directions on each wire, which significantly reduces the interference between the two wires.