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2021-04-03

AWS

1. Stockholm Europe

2. Frankfurt.
3. Paris

Based on : https://www.awsspeedtest.com/

Azure

1. Germany West Central Frankfurt
2. Switzerland North Zurich
3. West Europe Netherlands

Based on : https://www.azurespeed.com/Azure/Latency

Google Cloud Platform

1. Hamina Finland - europe-north-1
2. Frankfurt Germany - europe-west-3
3. Netherlands - erope-west-4

Based on : https://gcping.com/

Vultr

Based on :

1. Frankfurt
2. Netherlands
3. Paris

Modem vs Gateway vs Router

Modem — process the signal from ISP and interfaces to the home network .

https://www.youtube.com/watch?v=Ea4rMYM_Mz8

Modem:

• Not intlligent
• Not programmed
• Not data protection
• Do not has a firewall

Router — create a local network with each device has uniq ip adds.

• Intelligent device
• Every digital router contains a modem
• Router provides firewall func
• Tunel options provides (IPsec, GRE , PPTP ,OpenVPN tunes options)
• May include IO functionality.

Gateway — they provide protocol translation (zigbee, mudbus , celluar, PCI , RS-232 ….)

• Less traffic control
• Simple to configure
• I/O options
• Gateway is a protocol translator .

Switch — one port to many. But don’t assign different ip.

Network bridge — link devices together linear.

Network hub — dose not analyze traffic, just broadcast anything to every port .

Modem — Translates different form of data (analog to digital, digital to analog)

Gateway — Translates same data for different protocols

Router — includes a modem sometimes (wires to wifi for example)

RF modem

调制解调器（英语：Modem，modulator-demodulator的英文缩写）是一个将数字信号调变到模拟信号上进行传输，并解调收到的模拟信号以得到数字信号的电子设备

Модем (ағылш. modem, modulator-demodulator) — сандық сигналдарды аналогтық сигналдарға айналдыратын және керісінше амал жасайтын электрондық құрылғы.

Modem — modulator-demodulator

Modulations

Digital modulation is more immune to noise .

Binary digital modulation ;