Helping people with computers... one answer at a time.
When it comes to network segments, there's really one pipe that carries all of the information from all of the computers. And the information is colliding all the time.
This question is a little bit in broken English, but I'm going to read to you verbatim:
"How signals travel by cable? One by one or side by side? From LAN, many computers send and receive packets on a single telephone line. Whether they travel one after another or in lanes?"
In this excerpt from Answercast #57, I look at the way that data travels along network wires.
So, first of all - it's not a telephone line. It's an Ethernet connection.
When computers are on a LAN, the plugs may look kind of like a phone plug, but they're actually a little bit bigger and it's a completely different wiring scheme. A telephone works on exactly two wires, whereas Ethernet actually requires all eight connectors in that wire to be operational.
Now, with that little trivia out of the way, it's interesting to note that the answer is surprisingly "one by one." And in fact, there are no lanes.
Well... there's two lanes, I should say. On an Ethernet connection, there are in fact two lanes: a lane going out (in other words, a connection for transmitted data) and then one coming back (a connection for received data.)
When you get those all connected together (in say, a hub or a switch or a router), everybody's sending and receiving data at the same time, and in fact, they collide.
It is very common. A lot of the Ethernet communications protocol is all about detecting and handling collisions. The reason you and I don't notice this is that it happens so gosh darn quickly.
Packets themselves (once they get started, once you start transmitting a packet) are a very short burst of information. The system finds out if there's a collision.
In other words... Two people try to talk at the same time (or to use your terminology, two computers tried to occupy the same lane at the same time) and unlike an automobile collision, the computers can simply try again. And in fact, they will even try again at different times. They'll delay.
If you think about it: if you had two identical computers running identical software following identical rules, if they collided, they would follow identical paths to try again, which would likely cause them to collide again. So, built into this protocol are things like a certain amount of randomization that says, "OK, I'm going to wait this much and that guy's going to wait that much." And as a result, the packets will then get sent at different times and not collide.
But ultimately, the answer to your question is there's really one pipe. And that one pipe carries all of the information from all of the computers on a network segment.
Network segments can be isolated from one another. In other words if you
cross a router, one side of a router may have a completely different set of
traffic than the other. But when you take a look at a simple network connected
by a hub (or several computers that are connected somehow directly together), it
really does boil down to a single lane of traffic and everybody just sort of
collides like crazy, recovers, and tries again.
Next from Answercast 57 - If an open Wi-Fi hotspot displays a page asking me to login, does that make it secure?
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