Section 3. Understanding Ethernet and Switch Operations Flashcards
Q1-What does BASE mean in 100BASE-T and 1000BASE-T?
BASE in 100BASE-T and 1000BASE-T refers to the baseband signaling method. Baseband is a network technology in which only one carrier frequency is used. This means that when a device transmits, it uses the entire bandwidth on the wire and does not share it during the single time interval.
Q2-What is carrier sense multiple access collision detect (CSMA/CD)?
CSMA/CD describes the Ethernet access method.
In CSMA/CD, many stations can transmit on the same cable, and no station has priority over any other. Before a station transmits, it listens on the wire (carrier sense) to make sure that no other station is transmitting. If no other station is transmitting, the station transmits across the wire. If a collision occurs, the transmitting stations detect the collision and run a random backoff algorithm. The random backoff algorithm is a random time that each station waits before retransmitting.
Q3-What is UTP cabling?
Unshielded twisted-pair (UTP) cabling is a type of twisted-pair cable that relies solely on the cancellation effects produced by the twisted wire pairs to limit electromagnetic interference (EMI) and radio frequency interference (RFI).
UTP cable is often installed using an RJ-45 connector, and UTP cabling must follow precise specifications dictating how many twists are required per meter of cable. The advantages of UTP are ease of installation and low cost. A disadvantage of UTP is that it is more prone to EMI than other types of media.
Q4-What is the maximum cable length for UTP?
The maximum length is 100 meters or 328 feet.
Q5-What is a straight-through Ethernet cable, and when would you use it?
A straight-through Ethernet cable is wired the same way at both ends. This cable uses pins 1, 2, 3, and 6. The send and receive wires are not crossed.
You should use a straight-through Ethernet cable when connecting dissimilar devices (for example, data terminal equipment [DTE] to data communications equipment [DCE]). Examples include connecting PCs (DTE) to switches or hubs (DCE) or a router (DTE) to a switch or a hub (DCE).
Q6-What is a crossover Ethernet cable, and when would you use it?
A crossover Ethernet cable is a cable that has the send and receive wires crossed at one of the ends. In a Category 5 cable, the 1 and 3 wires are switched and the 2 and 6 wires are switched at one end of the cable.
You should use a crossover cable when connecting similar devices (DCE to DCE or DTE to DTE), such as connecting a router to a router, a switch to a switch or hub, a hub to a hub, or a PC to a PC.
Q7-What are the different UTP categories?
The categories of UTP cable are as follows:
Category 1: Used for telephone communications.
Category 2: Capable of data transmission speeds of up to 4 Mbps.
Category 3: Used in 10BASE-T networks. Speeds up to 10 Mbps.
Category 4: Used in Token Ring networks. Speeds up to 16 Mbps.
Category 5: Capable of data transmission speeds of up to 100 Mbps.
Category 5e: Supports speeds of up to 1 Gbps.
Category 6: Consists of four pairs of 24-gauge copper wires. Speeds up to 1 Gbps.
Category 6a: Supports speeds up to 10 Gbps.
Q8-What is the difference between single-mode fiber (SMF) and multimode fiber (MMF)?
The primary difference between SMF and MMF is the ability of the fiber to send light for a long distance at high bit rates. In general, MMF supports shorter distances than SMF.
Q9-What are three ways that LAN traffic is transmitted?
LAN traffic is transmitted one of the following three ways:
Unicast: Unicasts are the most common type of LAN traffic. A unicast frame is a frame intended for only one host.
Broadcast: Broadcast frames are intended for all hosts within a broadcast domain. Stations view broadcast frames as public service announcements. All stations receive and process broadcast frames.
Multicast: Multicasts are traffic in which one transmitter tries to reach only a subset, or group, of the entire segment
Q10-How many bits are in an Ethernet address?
Also called a MAC address, an Ethernet address is the Layer 2 address associated with the Ethernet network adapter. Typically burned into the adapter, the MAC address is usually displayed in a hexadecimal format, such as 00-0d-65-ac-50-7f.
Q11-What portion of the MAC address is vendor specific?
The first half or first 24 bits of the MAC address are vendor specific.
A MAC address is 48 bits and is displayed in hexadecimal. The first half of the address identifies the vendor or manufacturer of the card. This is called the Organizational Unique Identifier (OUI). The last half of the address identifies the card address.
Q12-What portion of the MAC address is vendor assigned?
The last 24 bits are vendor assigned.
Q13-What are the first 24 bits in a MAC address called?
These bits are the Organizational Unique Identifier (OUI).
Q14-What is an example of a Layer 2 address?
An example is a MAC address.
Q15-What is an example of a Layer 3 address?
An example is an IP address.
Q16-If a sending device does not know the MAC address of the destination device, what protocol is used to find the MAC address of the receiving device?
Address Resolution Protocol (ARP) is used to find the MAC address of the receiving device.
ARP is a local broadcast sent to all devices on the local segment to find the MAC address of a host.