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Week 4 Flashcards

(78 cards)

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1
Q

Modem

A

Short for modulator-demodulator.

A device that converts data from a digital format to an analog format. This would connect to a phone in the early internet days. The demodulator would get sound data and make it digital.

Reached a max of 56 kb/s in 1990s.

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2
Q

Why does coaxial cable use frequency division modulation based multiplexing with analog frequency

A

Easier physical / mathematical implementation

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3
Q

Multiplexing

A

The general technology that frequency division modulation is part of. Sending multiple pieces of information down the same tunnel (could also use advanced math for simultaneous access, vary by time, or randomly assign smaller frequencies).

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4
Q

Baseband

A

A single channel per cable. This one channel takes up every frequency. This has low bandwith, but low latency

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5
Q

Broadband

A

Any method of communication that doesn’t have the lowest base transmission of zero hertz included.

Often this is because it is using frequency division modulation. In this case, it has more bandwidth and higher latency.

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6
Q

Backbone

A

Large collection of fiberoptic cables. This uses baseband instead of broadband for lower latency. However, baseband actually has a different meaning here, meaning that it only transmits one sequence of binary at a time. In practice though, it transmits many packets of binary using the fiberoptics equivalent of broadband - Wavelength-division multiplexing.

Thus, we’re told it sacrifices bandwidth for latency, but this isn’t really the case.

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7
Q

Information transfer used in the internet

A

Satelite, wireless LAN, copper cables (coaxial and ethernet), fiberoptics

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8
Q

Protocols

A

The only non-hardware nuts and bolts thing

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9
Q

Servers

A

Notably considered and end system

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10
Q

Network core

A

Anything that isn’t an end system (though this is only two things)
1. Routers
2. Switches

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11
Q

Types of IP packets

A

UDP - User Datagram Protocol is used in real time systems where dropping a packet is preferable to waiting for it to be rebroadcast.
TCP - Transmission Control Protocol is reliable but slower than UDP due to guaranteeing that every packet is received in order.

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12
Q

Coaxial cable

A

Used early on to connect radio broadcast towers and today for multiplexed TV and internet.

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13
Q

Overhead

A

Timing delay introduced by guaranteeing packets aren’t lost with UDP.

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14
Q

Increase in percent of population connected

A

45 to 60

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15
Q

Devices per capita

A

2.5 to 3.5

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16
Q

Average speed in Mbps

A

40 to 75

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17
Q

Traffic / User / Month in GB

A

16 to 50

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18
Q

Most disconnected people

A

Africa and India

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19
Q

IP Traffic in 2022

A

333 Exabytes (more than peta, more than terra)

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20
Q

Internet Users

A

55% Asian
10% African / South American
15% European

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21
Q

Users in billions

A

Facebook 2.7
YouTube 2
Facebook Messenger 1.3
Instagram 1.2

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22
Q

Revenue in Billions by Region

A

1,600 Asia
1,000 North America
566 Europe

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23
Q

Revenue in Billions by Holiday

A

13 Cyber Monday
10 Black Friday
6 Thanksgiving

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24
Q

Parts of the internet

A

Network edge, access network, network core

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25
Server Uses
Store and consume data
26
Network core
1. Routers 2. Switches 3. National / Global ISPs 4. Local / Regional ISPs
27
Access network types
1. Mobile network 2. Satellite network 3. Terrestrial ISP
28
IP Protocol Basics
- Has ordering syntax and formatting like a human language - TCP Connection request - TCP Connection reply - Requester is the client - Awaiter is the server
29
Number of collected devices
28 billion
30
2 Core connectives
Communication links (ethernet, coaxial, and fiber) and packet switches
31
Packet switch
A device that takes a packet from an ingoing link and relays it on an outgoing link
32
Router
Type of switch used in the network core (not technically a router, its just that some layer three switches can perform routing).
33
Route/Path
The sequence of switches a packet traverses
34
IP
Internet protocol
35
IETF
Internet engineering task force
36
ISP Types
Lower tier ISPs are connected only by upper tier ISPs. Lower tiers include residential, cellular, and corporate.
37
Distributed Applications
An application with a client side and a server side, for example, all web applications
38
Socket interface
Rules for a server end system to get data to a client end system.
39
Protocol
Defines the format and order of messsage between two communiteing eneties as well as actoins upon the reciept of a message or other event
40
Network edge
Includes cleints and servers
41
Blades
Full computers stored on racks in datacenters 20 blades per rack
42
Data center
Large collection of server type hosts
43
AWS
Runs amazon, gives amazon employees recourses to play with, and provides compute for other developers projects.
44
Digital subscriber line
This is offered by the local telephone company, on a telephone wire. It uses a form of digital frequency modulation to split up the spectrum. 0-4 kHz Telephone 4-50kHz Upload 50-1000kHz Download Maximum combined upload / download speed of 1Gbps Outgoing data is translated from audio to digital by a DSLAM, which must be placed every 5-10 miles. At home, a splitter will connect a DSL modem and a home phone to the telephone line. Standard rate pairs in Mbps 25, 3.5 52, 16
45
DSL FDM
0-4 kHz Telephone 4-50kHz Upload 50-1000kHz Download
46
DSL total two way capacity
1 Gbps
47
Maximum DSLAM distance
5-10 mi
48
DSL hardware
At home, a splitter will connect a DSL modem and a home phone to the telephone line.
49
DSL rate pairs
Standard rate pairs in Mbps 25, 3.5 52, 16
50
Cable internet access
Uses television companies' television cables. Service provided by the same company that provides TV. Coaxial cables connect houses to fiber nodes which then connect to regional offices via fiber cables. Fiber cables at each neighborhood junction can connect 500-5000 homes. Requires a cable modem. The combined network is called HFC - Hybrid Fiber Coaxial. It is divided into upstream and downstream channels. FDM is regulated by DOCSIS 2.0 and 3.0. In Mbps: 4, 30 100, 1,200
51
HFC Hardware
Coaxial cables connect houses to fiber nodes which then connect to regional offices via fiber cables. Fiber cables at each neighborhood junction can connect 500-5000 homes. Requires a cable modem. The combined network is called HFC - Hybrid Fiber Coaxial.
52
DOCSIS 2.0/3.0
FDM is regulated by DOCSIS 2.0 and 3.0. In Mbps: 4, 30 100, 1,200
53
Direct FTTH (Fiber to the home)
One fiber line from central office to the house
54
Shared FTTH (Fiber to the home)
Splits into individual fiber lines very near to the house.
55
Optical distribution architectures
Active optical. This is switched Ethernet and it's not covered yet. Passive optical. Covered.
56
Passive optical network
Used in Verizon FiOS Uses optical NETWORK terminators in homes. About 100 individual homes connect to an optical splitter, which connects to an optical LINE terminator in a central office, which converts from light to digital. The optical NETWORK terminator in the home will connect to a wireless router for wifi.
57
Who uses passive optical network
Verizon FiOS
58
Homes per optical splitter
100
59
Line terminator vs network terminator
Network terminator is in home. Line terminator is in CO
60
5G Fixed wireless.
Uses beam forming technology to send data from provider's base station to a modem in the home. Wireless router connects to the modem.
61
Network access from a university
End user ethernet / Wireless: 100 Mbps Server ethernet: 1000Mbps
62
Wide Area Wireless Access Network (4G)
60 Mbps
63
Guided media
Any physical object: fiberoptics, coper, coaxial cable
64
Unguided media
Anything nonphysical: wireless lan, satelite
65
Twisted pair copper wire
Cheap Used in 99% of telephone calls Two insulated wires, 1mm thick, in a spiral pattern. Twisting reduces electrical interference of nearby wires. One pair of wires is one path of communication. Bundled in large quantities within buildings. Can transmit 10Mbps to 10Gbps 6A cables can go 100M at 10Gbps
66
Twisted pair capacity
Can transmit 10Mbps to 10Gbps
67
Coaxial cable
Concentric copper wires allow for insulation, shielding, and therefore faster transmission. FDM
68
6A
6A cables can go 100M at 10Gbps
69
Fiberoptics
Thin glass rod where one pulse represents one bit of information. No interference can occur. Up to 100Gbps Up to 100km Only used for long haul because cables are cheap, but connectors are expensive. Used as the backbone of telephone and internet service. Speeds defined as OC-n, where speeds are a multiple of 51.8 Mbps
70
Fiberoptics max speed / distance
Up to 100Gbps Up to 100km
71
Fiberoptics speed specifications
Speeds defined as OC-n, where speeds are a multiple of 51.8 Mbps
72
Terrestrial radio
Can go through things Very short - 1-2M Wide area - 10km
73
Shadow fading
noise from physical objects
74
multipath fading
noise from reflections
75
Geostationary satelites
Stay in one place above the earth: 36,000km. 280ms delay. 100Mbps data transfer.
76
Low Earth Orbiting
Rotate earth and communicate with each other and ground stations. Requires many for continuous access. Currently offered by starlink.
77
Earth based microwave transmitters and recievers
Called ground stations
78
Satelites
Recived transmissions on one frequence band and regenerate it on another.
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