Basic Network Terms Discussed: Part 1

Attenuation - the farther a data signal travels down a cable, the weaker the signal becomes

Broadcast message - when computers on a network first sign on to the network they send a broadcast message to every computer and device on the network. They do this to let those devices know they are there and to have the other devices announce themselves.

There are other broadcast messages that are sent for other reasons. The main thing to know is that they slow the network down because every device gets the message even if it was not intended for it. Every device replies, causing a waste of time and bandwidth. With so many signals being sent at once you could have a data collision.

Hub - A hub receives a data signal and restores it back to its original strength, therefore extending the physical range of the network

A hub is called a "dumb" device because it amplifies the signal "as is". If the signal is corrupted or noisy, the hub strengthens the noise as well and passes it on.

It's important to know that a hub passes ALL signals that it receives even broadcast messages.

Switch - a switch is called an "intelligent" device. Not only does it strengthen a signal but it will also attempt to remove noise and rebuild the signal as it was intended - The main benefit of a switch is that it keeps a record of every device that talks to it. So the next time computer A needs to talk to computer B, the switch can connect them directly so there is no need for a broad cast message.

A switch can be configured to not pass broadcast messages otherwise it will.

Router - a router is an intelligent device. It does NOT pass broadcast messages ever. A router segments or actually separates one part of a network from another. You can have group A and group B both connected to the router but unless it is configured to allow the groups to talk to each other they will not even know the other exists. This is down to cut down on network traffic.

Protocol - a protocol is sometimes called a language but it is NOT a language. It is a set of procedures or rules for one device to talk to another.

Example - Bowing when you meet the Queen of England

Example for a network computer- send start bit. Then send data. then send stop bit. Wait for confirmation that the first packet was received before sending the next packet.

Gateway - a gateway joins two networks together. The terms router and gateway are interchangeable. A router is a gateway. A computer can be set up to be a router/gateway. If you connect to the internet through another computer, then that computer is a gateway. It routes you to the internet.

It can separate a network but also allow passage. When you look at the IP information of a network connection, it lists the IP for the gateway. This IP is actually the IP of the router. They are the same.

An IP address consists of 4 octets 000.000.000.000 octet = eight Where does the eight come from?

Here:

Each octet has a decimal range of 0 - 255 That same range in binary uses eight digits 00000000.00000000.00000000.00000000

Octet 1 Octet 2 Octet 3 Octet 4

00000000 = 0 00000001 = 1 0000010 = 2 00000011 = 3 00000100 = 4 do this all the way up to 255

So 00000011.11111111.00000000.00001111 = 3.255.0.15

Do you know binary counting?

8 7 6 5 4 3 2 1 places

128 64 32 16 8 4 2 1

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1 0 0 0 1 0 1 1

I put a "1" under 128, 8, 2 and 1 so add those together 128 + 8 + 2 + 1 = 139 010001011 in binary = 139 decimal

128 64 32 16 8 4 2 1

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1 1 1 1 1 1 1 1

I put a "1" under all the numbers add them and they equal 255 - the max in the 0-255 range

so 11111111.11111111.00000000.00000000 = 255.255.0.0