Module 4.1 & 4.2: Ethernet Flashcards
What are the three network topologies?
- Physical bus, logical bus
- Physical star, logical bus
- Physical star, logical star
What devices use Ethernet networks?
- NICs
- Hubs
- Switches
- Routers
Which cable types support Ethernet?
- UTP with RJ45 connectors.
- Fiber optics cables
- Coaxial cables (usually for older implementations.)
Which contention based media access method does Ethernet use?
Carrier Sense, Multiple Access/Collision Detection.
CSMA/CD
Explain what CSMA/CD is.
- It defines the steps network devices take when two devices attempt to use a data channel simultaneously. Ethernet networks use CSMA/CD, including 1000BaseT.
- Because all devices have equal access (multiple access) to the transmission media, a device listens to the transmission medium to determine whether it is free before sending data (carrier sense).
- If it is not free, the device waits a random amount of time and listens to the transmission medium again. If it is free, the device transmits its message.
- If two devices transmit at the same time, a collision occurs. The sending devices detect the collision (collision detection) and send a jam signal to notify all other hosts that a collision has occurred.
- Both devices wait a random length of time before attempting to resend the original message (backoff).
What is Half-duplex mode?
A collision detection capability.
- Collision detection is turned on.
- The device can send or receive in only one direction at a time.
- Devices connected to a hub must use half-duplex communication.
- Up to the rated bandwidth (100 Mbps for 100BaseT and so on.)
What is Full-duplex mode?
A collision detection capability.
- Collision detection is turned off.
- The device can send and receive at the same time.
- Mode requires full-duplex capable NICs.
- Mode requires switches with dedicated switch ports (a single device per port).
- Double the rated bandwidth (200 Mbps for 100BaseT and so on.)
Which address do Ethernet devices work with?
MAC Address.
What is a Frame?
A frame is a unit of data that is ready to be sent on the network medium.
What are the components of an Ethernet Frame?
- The preamble is a set of alternating ones and zeros terminated by two ones (11) that mark it as a frame.
- The destination address identifies the receiving host’s MAC address.
- The source address identifies the sending host’s MAC address.
- The data is the information that needs to be transmitted from one host to the other.
- Optional bits pad the frame. Ethernet frames are between 64 and 1518 bytes in size. If the frame is smaller than 64 bytes, the sending NIC places junk data in the pad to make it the required minimum of 64 bytes.
- The cyclic redundancy check (CRC) is the result of a mathematical calculation performed on the frame. The CRC helps verify that the frame contents have arrived uncorrupted.
What is the Standard, bandwidth, cable type and maximum segment of length for basic Ethernet?
Standard: 10BaseFL
Bandwidth: 10 Mbps (full-duplex)
Cable Type: Fiber Optic
Max Seg Length: 1000 - 2000 meters.
What is the Standard, bandwidth, cable type and maximum segment of length for Fast Ethernet?
Standard: 100BaseTX
Bandwidth: 100 Mbps (half duplex) 200 Mbps (Full Duplex)
Cable Type: Twisted pair (Cat5 or higher), uses 2 pairs of wires.
Max Seg Length: 100 meters.
What is the Standard, bandwidth, cable type and maximum segment of length for Gigabit Ethernet?
Standard:
- 1000BaseCX (short copper)
- 1000BaseSX (Short)
- 1000BaseLx (Long)
Bandwidth: 1000 Mbps (half duplex), 2000 Mbps (Full duplex)
Cable Type: Special Copper (150 ohm), Fiber Optic
Max Seg Length: 220 to 550 meters depending on cable quality, 550 meters/ 5 kilometers
* Min for 1000 Mbps Cat5e
What is the Standard, bandwidth, cable type and maximum segment of length for 10 Gigabit Ethernet?
Standard: 10GBaseLR
Bandwidth: 10 Bbps (full-duplex only)
Cable Type: Single mode fiber optic
Max Seg Length: 10 kilometers
