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General Science => General Science => Topic started by: NTYNUT on 29/08/2018 08:13:35

Title: What is Ethernet?
Post by: NTYNUT on 29/08/2018 08:13:35

hello
how does ethernet work with modem with computer
I have seen does power go from computer to modem or modem to computer i am searching but i can't find

Title: Re: What is Ethernet?
Post by: evan_au on 29/08/2018 11:20:56

Quote from: NTYNUT

how does ethernet work between modem and computer?

Modern Ethernet in the home and office uses a cable with 8 copper wires, arranged in 4 twisted pairs. The most modern cable is called "Category 6A", or "Cat 6A", and supports transmission at speeds of up to 10Gbps for up to 100m.
https://en.wikipedia.org/wiki/Category_6_cable

Today, most home computers can transmit at 1 Gbps; 10Gbps is used mainly in data centers.
At high speeds (>1Gbps) or long distance (>100m), optical fiber is preferred over copper wires.
For short distance (<30m) and mobile connection, wireless ethernet is often used (WiFi).

The modem and computer have specialised Ethernet chips that communicate with each other to check the cable connections, and then establish simultaneous communication in both directions at the highest speed they both support.  The computers can send blocks of data which are most often between 64 Bytes and 1520 Bytes in length (although some applications allow blocks of up to 9000Bytes).
See: https://en.wikipedia.org/wiki/Ethernet

Quote

I have seen does power go from computer to modem or modem to computer i am searching but i can't find

There is a standard called Power over Ethernet (PoE). This allows one device to supply 0.5W to 100W of power over a copper ethernet cable.

Which end provides the power is a question of which end (or both) have power available:
- Most home computers and modems don't use POE; both devices need their own 230VAC power plug
- A lot of modern business telephones connect via Ethernet; POE is a good option that saves cost in the phone. It also simplifies provision of an emergency battery power supply for all the phones. But most people today use smartphones, which have their own battery power supply.
- Many businesses have WiFI hotspots mounted on ceilings and in hallways - locations that often don't have a convenient power point. So a router with POE on each floor is used to provide power and communications for all the WiFi hotspots on that floor.
See: https://en.wikipedia.org/wiki/Power_over_Ethernet

Title: Re: What is Ethernet?
Post by: NTYNUT on 29/08/2018 11:24:40

Hello
How to get 5V from Ethernet cable

Title: Re: What is Ethernet?
Post by: wolfekeeper on 29/08/2018 22:10:17

https://en.wikipedia.org/wiki/Power_over_Ethernet

Title: Re: What is Ethernet?
Post by: evan_au on 30/08/2018 11:41:51

If you want to power something with 5V, it will be easier to use a USB socket. Most modern computers (and modern cars) have a USB socket.

POE is still fairly rare in retail equipment.