Ethernet Basics Flashcards

(62 cards)

1
Q

Ethernet

A

networking technology based on bus topology

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2
Q

topology of every Ethernet since 90’s

A

hybrid star-bus

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3
Q

[blank] prevent monopolization of shared cable

A

frames

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4
Q

Ethernet traffic management

A

each computer listens on segment

sends frame when no other transmission are detected

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5
Q

basic Ethernet frame

A
1 - MAC address of frame's recipient
2 - MAC address of sending system
3 - type of data
4 - data
5 - pad (if needed)
6 - FCS
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6
Q

preamble

A

7-byte series of binary followed by a 1-byte start frame

allows NIC to realize frame is coming & know where it starts

added by sending NIC

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7
Q

MAC address (bit & byte)

A

48-bit

6-byte

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8
Q

pad

A

minimum frame size - 64 bytes

fills remaining space when content does not reach 64 bytes

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9
Q

CSMA/CD

A

carrier sense multiple access/collision detection

determines which computer should use shared wire at a given moment

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10
Q

carrier sense

A

each node examines cable before sending frame

traffic detected - wait a few milliseconds - recheck

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11
Q

multiple access

A

all machines have equal access to the wire if cable is free

1st-come, 1st-served

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12
Q

collision

A

nodes transmit signal simultaneously

both signals are lost

hub sends overlapping signals - NICs immediately detect collision - stop transmitting

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13
Q

maximum acceptable collisions

A

10%

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14
Q

collision domain

A

group of nodes that have the capability of sending frames at the same time as each other

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15
Q

Ethernet collision domains are [blank]

A

segments or connected segments

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16
Q

bus Ethernet

A

thicknet - 10Base5 - vampire tap

thinnet - 10Base2 - T connector attached to NIC

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17
Q

thinnet specifics

A

RG-58 coax

BNC connects on ends

185 m limit

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18
Q

half-duplex vs. full-duplex

A

half - communicate in 1 direction at a time

full - send/receive simultaneously

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19
Q

TIA/EIA

A

Telecommunications Industry Association / Electronics Industries Alliance

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20
Q

current TIA/EIA standard

A

568C

same wiring standards as A & B

new name “ANSI/TIA-586-C”

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21
Q

TIA/EIA 568A

A
1 - G / W
2- G
3 - O / W
4 - Bl
5 - Bl / W
6 - O
7 - Br / W
8 - Br

G - send | O - receive

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22
Q

TIA/EIA 568B

A
1 - O / W 
2 - O
3 - G / W
4 - Bl
5 - Bl / W
6 - G
7 - Br / W
8 - Br

O - send | G - receive

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23
Q

sending pins

A

1 & 2

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24
Q

receiving ping

A

3 & 6

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25
10BaseT
- Speed = 10 Mbps - Signal Type = baseband - Distance = 100 meters between hub and node - Node Limit = No more than 1024 - Topology = star-bus, physical star, logical bus - Cable Type = CAT 3 or better UTP cabling with RJ-45 connectors
26
10BaseFL
- Speed = 10 Mbps - Signal Type = baseband - Distance = 2000 meters between hub and node - Node Limit = no more than 1024 - Topology = star-bus, physical star, logical bus - Cable Type = multimode fiber-optic cabling with ST or SC connectors
27
[blank] used to interconnect different types of Ethernet
media converter
28
couplers
extend Ethernet segments double-female connectors add machines not originally envisioned
29
adding more ports for additional nodes
add more hubs add a bridge
30
2 methods of connecting hubs
uplink port > straight through cable from uplink port on 1 hub to any other port on the other hub crossover cable > send/receive pairs are reversed to create operational connection - connects to regular port
31
configuration for connecting multiple hubs
must use daisy chain > uplink port connects to 1 port on each attached hub
32
different names for uplink ports
crossover > MDI-X > MDI > OUT
33
line (marking) on hub between 2 ports may indicate [blank]
only 1 of these 2 ports may be used at a time
34
MDI
media dependent interface regular port on hub or switch
35
MDIX or MDI-X
media dependent interface crossover uplink port
36
ends of crossover cable
1 end TIA/EIA 568A 1 end TIA/EIA 568B
37
rollover cable
RJ-45 connector on 1 end > RS-232 serial port on the other used to connect computer directly to Cisco switch or router
38
straight-through cable connecting 2 PCs directly
both PCs will try to use the same send/receive wires
39
plug 2 PCs into a hub
hub electronically crosses data wires 1 NIC sends > the other receives
40
plug 2nd hub into 1st hub using regular ports
cross the cross create a straight-through connection
41
bridge
acts like a repeater or hub to connect 2 Ethernet networks filters & forwards traffic between segments based on MAC address preserves bandwidth *layer 2 - work with MAC addresses"
42
filter
stop traffic from crossing from 1 network to the next
43
forward
pass traffic from 1 side of the bridge to the other
44
10BaseT network with a hub can support [blank] signals on the wire at a time
1
45
switch
effectively creates point-to-point connection between 2 computers on a network allows for full access to the network bandwidth essentially eliminate collisions
46
SAT
source address table table of MAC addresses generated by a switch
47
SAT creation
switch starts off just like a hub > forwards incoming signals to all other ports frames forwarded > switch copies MAC addresses quickly creates table of MACs for each connected computer
48
how switches allow access to full network bandwidth
each port on switch is its own collision domain switch can buffer incoming frames
49
half- vs. full-duplex switches
half-duplex have to follow CSMA/CD full-duplex do not > don't have to daisy chain
50
Layer 2 switches
switch filters run on MAC addresses
51
unicast message
only sent to recipient MAC address
52
broadcast message
sent to all connected ports
53
domains of switch vs. hub networks
switch - broadcast domain hub - collision domain
54
Ethernet before switches
no difference between broadcast & collision domain all messages were broadcast - went to all nodes all nodes connected to the same bus collisions were normal
55
bridging loops (switching loops)
switches can be connected in any fashion redundant connections (loops) may be created crashed early switch networks
56
STP
Spanning Tree Protocol enabled switches can detect loops > communicate with other switches > set looped port's state to blocking
57
BPDU
Bridge Protocol Data Unit type of frame used by switches to communicate with each other to determine things like distance between them & changes to the network
58
STP-enabled switch receives frame from MAC address not contained in SAT
switch sends out a signal on every port to determine location of new device flooding all switches exchange information > update tables > set ports to forwarding or blocking convergence
59
bridge loops with modern switches
STP enabled on all modern switches bridge loop designed intentionally to provide fault tolerance link fails > blocking port becomes forwarding port to maintain traffic flow
60
portfast
always forward traffic
61
RTSP
Rapid Spanning Tree Protocol significantly faster convergence time 6 seconds compared to 50 seconds
62
switch troubleshooting
connected device can't access network look for obvious changes link lights > try a different port check all connections & cables replace cable or switch with 1 that is known to work