Chapter 3: Ethernet Basics Flashcards

1
Q

What are the five fields of a basic ethernet frame ?

A

Destination address, source address, type of data, data, and frame check sequence (FCS)

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2
Q

Preamble

A

8 byte series that always precedes the frame. Gives receiving NIC heads up and sending NIC attached it

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3
Q

What does the type field help with ?

A

Interpreting the frame contents at a very basic level

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4
Q

What is the minimum frame size ?

A

64 bytes

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5
Q

Pad

A

Extra filler data added to meet the minimum frame size

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6
Q

10BASE-T

A

A verzion of ethernet consisting of two or more computers connected to a central hub

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7
Q

Explain the naming convention on 10BASE-T

A

10 referring to Mbps, BASE to baseband, and T for twisted pair

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8
Q

What is the required cable and its details used for 10BASE-T ?

A

Cat 3(or higher), two pair, UTP cable

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9
Q

Which connector did 10BASE-T introduce ?

A

RJ-45

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10
Q

Which pins send data and which receive in 10BASE-T ?

A

1 and 2 send. 3 and 6 receive.

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11
Q

Can 10BASE-T send and receive data simultaneously ?

A

No

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12
Q

What is an NIC that runs half duplex mode ?

A

NICs that can only communicate in only one direction

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13
Q

What is the color code of a four-pair UTP according to TIA/EIA568A?

A

GGOBBOBrBr

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14
Q

What is the distance limitation for 10BASE-T ?

A

100 meters between the hub and computer

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15
Q

What is the distance limitation for 10BASE-T ?

A

100 meters between the hub and computer

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16
Q

What is the node limit for 10BASE-T ?

A

1024 nodes per hub

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17
Q

What is the topology used for 10BASE-T ?

A

Star-bus

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18
Q

What 3 key weaknesses did 10BASE-FL address ?

A

Used fiber optic, which could travel up to 2 kilometers, immune to EMI, and harder to tap into for security purposes

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19
Q

What are the cable details for 10BASE-FL ?

A

MMF 62.5/125 um (OM1) with ST or SC connectors

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20
Q

How do you interconnect different Ethernet versions ?

A

Media converter

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21
Q

How do ethernet networks handle the issue of potential collisions ?

A

Carrier-sense multiple access with collision detection (CSMA/CD)

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22
Q

Is CSMA/CD enabled in modern full-duplex networks ?

A

No

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23
Q

What happens after a collision ?

A

Both transmissions are lost, and both nodes stop transmitting.

A number is generated for waiting before trying again

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24
Q

What is a group of nodes that are able to send frames at the same time, resulting in collisions ?

A

Collision domain

25
Bridge
Device that connects two networks and passes frames between them based on the MAC address
26
What did Ethernet switches do ?
Created point-to-point connections between two conversing computers. Giving full bandwidth of the network
27
What does the switch copy on the MAC address table ?
The source MAC address
28
Do switches know where to send frames initially ?
They forward all frames until they complete port mapping
29
Is each port on a switch a collision domain ?
Yes
30
Can switches handle two nodes sending data at the same time ?
Yes, they can buffer incoming frames which avoids collisions
31
What are switches that filter traffic based on MAC addresses ?
Layer 2 switches
32
Whats a common name for a switches network ?
Broadcast domain
33
What is a switch with a single point of failure ?
Where all nodes are connected to that single switch
34
Uplink port
Connect two switches using a straight-through cable One end of the cable to uplink port and the other to any regular port
35
Do modern switches need an uplink port ?
No, they use auto-sense
36
Crossover cables
Twisted pair that reverses the sending and receiving pairs on one end of the cable TIA/EIA 568A - TIA/EIA 568B
37
What can crossover cables be used for today ?
Interconnecting older switches
38
Switching loops or bridging loops
Redundant connections in a network
39
Spanning tree protocol (STP)
Eliminated the problem of accidentally switching loops
40
What do BPDUs help detect ?
Potential loops before they happen
41
Special STP frames ?
Bridge protocol data units (BPDU)
42
Root bridge
Where one switch is the center of STP
43
What are root bridges used for ?
Reference point for switches to maintenance a loop-free topology
44
Blocking state for certain ports
Doesn't send or receive frames
45
Can ports in the blocking state hear configuration BPDUs ?
Yes
46
Topology change notification (TCN) BDPU
Enables the switch to rework themselves around the failed interface or device
47
PortFast
Enables the interface to come up right away without the latency introduced by STP
48
Should a switch port connected to a PC participate in STP ?
Never
49
What switch port configuration prevents TCN BPDU from being sent out every time a PC is turned on or off ? What are some side effects ?
PortFast Causes switches to flush out source address table and relearn MAC addresses
50
BPDU guard
Moves a port configured with PortFast into an errdisable state (error occurred, disabled)
51
What could happen to ports configured with PortFast when they receive a BDPU ?
Could start a switching loop
52
Root guard
Moves a port into a root-inconsitent state if it's acting as the root bridge
53
Root guard
Moves a port into a root-inconsitent state if it's acting as the root bridge
54
What does a root-inconsistent port do automatically ?
Moves into a forwarding state once the BPDUs stop
55
What was STP replaced with
Rapid Spanning Tree Protocl (RSTP)
56
Speed comparison between STP and RSTP to return to convergence ?
50 seconds for STP and 6 seconds for RSTP
57
Main problems of switches
Physical damage or dead ports
58
5 steps for troubleshooting a switch
The device that plugged in can not connect to the network, Search for obvious damage, Check link lights, Inspect cables, Replace the switch or cables for a known-good device