Chapter 4: Ethernet Basics Flashcards
Ethernet hubs take an incoming packet and ________ it out to the other connected ports.
repeat
What is appended to the beginning of the Ethernet frame?
Preamble
Which networking devices can use the Spanning Tree Protocol (STP)?
Switches
What device directs packets based on MAC address?
Switch
What is the IEEE committee that controls Ethernet standards called?
802.3
What topology does Ethernet use?
Star bus
What is Ethernet?
A standard for a family of network technologies that share the same basic bus topology, frame type. and network access method.
What is the purpose of a preamble on a frame?
It gives a receiving NIC time to realize a frame is coming and to know exactly where the frame starts.
What does the type field of an Ethernet frame do?
Helps the receiving computer interpret the frame contents at a very basic level. (IPv4 or IPv6)
What is the minimum size of an Ethernet frame?
64 bytes
What happens if an Ethernet frame has fewer than 64 bytes of data?
The sending NIC will automatically add extra data (padding)
What is CSMA/CD?
Ethernet networks use a system called carrier sense multiple access/collision detection (CSMA/CD) to determine which computer should use a shared cable at any given moment.
What is a collision domain?
A group of nodes (NICs/computers) that have the capability of sending frames at the same time as each other resulting in collisions.
What do the nodes do if a collision occurs?
Each node stops transmitting, determines a random time to wait, then retransmits.
What is the average maximum percentage of collisions in an Ethernet network?
10 percent
What is the central box for 10BaseT?
A hub
Which pins of an RJ-45 connector are used to send data? receive data?
Pins 1 and 2 are used to send data
Pins 3 and 6 are used to receive data
What does it mean for a NIC to run in half-duplex mode?
The NIC can only communicate in one direction at a time, i.e. cannot send while receiving and vice versa.
What does it mean for a NIC to run in full-duplex mode?
The NIC can send and receive at the same time.
What is the arrangement of wires according to the TIA/EIA 568A standard?
WG G WO B WB O WBr Br
What is the arrangement of wires according to the TIA/EIA 568B standard?
WO O WG B WB G WBr Br
Fill in the following qualities of 10BaseT
1) Speed:
2) Signal Type:
3) Distance:
4) Node Limit:
5) Topology:
6) Cable Type:
7) Connector:
1) 10 Mbps
2) Baseband
3) 100m between hub and node
4) 1024/hub
5) Star bus
6) CAT3 or better UTP
7) RJ-45
Fill in the following qualities of 10BaseFL:
1) Speed:
2) Signal Type:
3) Distance:
4) Node Limit:
5) Topology:
6) Cable Type:
7) Connector:
1) 10Mbps
2) Baseband
3) 2000m between hub and node
4) 1024/hub
5) Star bus
6) Multimode fiber
7) ST or SC
What is a media dependent interface?
A regular old port on a hub or switch.
What is a media dependent interface crossover (MDIX)?
An uplink port on a hub.
What is a coupler?
A connection device used to extend an Ethernet segment
What are the two ways you can connect hubs?
1) Uplink ports
2) Crossover cables
What kind of cable do you use for connecting hubs using uplink ports?
Straight-through (both ends the same wire arrangement)
Where do you insert the cable ends when connecting hubs using uplink ports?
One end of the cable in the uplink port of one hub and the end to any regular port on the other hub.
What is a crossover cable?
A UTP cable that has one end arranged according to TIA/EIA 568A and the other according to TIA/EIA 568B.
Where do you insert the cable ends when connecting hubs with crossover cables?
Each end is plugged into a regular port.
What is a bridge?
A bridge acts like a repeater or hub to connect two Ethernet networks, and filters and forwards traffic between those segments based on the MAC addresses of the computers on those segments.
What does it mean to filter traffic?
Stop it from crossing from one network to the next.
What does it mean to forward traffic?
Pass traffic originating on one side of the bridge to the other.
What is the advantage of switches over hubs?
A switch effectively creates point-to-point connections between two conversing computers, so every conversation between two computers gets the full bandwidth.
A switch stores copies of the MAC addresses of each connected computer in a table called a ___________.
Source Address Table (SAT)
Why can two nodes connected to a switch send data at the same time?
Each port on a switch is in its own collision domain.
What is a bridging loop?
A redundant connection between switches
What is Spanning Tree Protocol (STP)?
STP allows switches to detect loops and set the looped port’s state to blocking
What is the frame called that STP-enabled switches use to communicate with each other?
Bridge Protocol Data Unit (BPDU)
What is the stable state of a switch referred to as?
Convergence
What are the steps for troubleshooting a basic hub/switch?
1) Check for obvious physical damage
2) Check for link lights, and try a different port if necessary
3) Check for cable damage
4) In the end, replace it
