I mean in like how do we send a signal that could casted over to the other side of the world. Like do we send it to a satellite then send it back or do we send the signal on earth, I’m confused
In: Technology
Typically the WAN uses fiber optics rather than satellites.
A router looks at each incoming data packet, inspects the IP address, and then uses a large table in memory to look up which line it should send the packet down to get it closer to that address.
Most of the long haul on an around the world trip will be on fiber optic cables buried underground and on the sea floor.
If you have a command line available, type “traceroute google.com” or to some other destination (except on Windows, it’s “tracert”), and you’ll see a few hops to get to the destination. Each hop is a router that makes a decision on how to get to the destination. Those routers are computers, mostly expensive, specialized computers built just to make those decisions quickly, to keep track of how to reach everything on the Internet, and to do it quickly and reliably. Between each hop is fiber or copper cabling, or wireless links.
Intercontinental communications are typically done with undersea fiber optic cables. Satellites are used for this too, but have less bandwidth and reliability; So they’re significantly less common, and mostly used for providing internet to remote locations that have no wired connections available.
Undersea cables use extremely strong armor and shielding to protect themselves from the elements. They’re typically buried slightly underneath the sand at the bottom of the ocean. They’re planned in advanced to go through the most shallow points of the ocean.
almost all internet backbone traffic is transferred over copper wire or fiber optic cable. Since the days of telegraphy we have been able to lay cables across the ocean floor in order to transfer signals between continents. The distance to send a signal to satellite and back to earth again is almost always greater than the distance to send the signal over a cable, even if you’re going halfway around the planet. Most communication satellites orbit at around 22,000 miles, so the round trip distance for a signal is 44,000 miles, while the circumference of the earth is only 24,000 miles.
Physically, cables in the ground and undersea cables mostly which go through big telecommunications hubs. Sattelite bandwidth is too expensive to be used for most of it.
The devices moving around and directing all the traffic are called routers. There’s different languages the routers use called protocols to talk to each other and there are about 5 major ones to pick from and they have their own advantages and disadvantages. Within those protocols there are different ways to do home and destination addresses so the information can find it’s way to where it needs to go. IP addresses have become the most popular, that and internal codes are how the routers identify and split all the data up into little packets and verify it made it there before reassembling it on the other end.
For the usual traffic, each router builds it’s own table (kind of like a spreadsheet) which lists all the routers it is closely connected to for directing traffic to help speed things up. There’s usually backup routes listed in case the main one it wants to use goes down or the line between them is cut, etc…
The routers all get their own set of rules programmed in to what to allow and disallow and each connection on the router can have it’s own custom speed, protocol, security, encription and rules applied to it. To ease the burden on routers so they can spend their CPU time routing more, firewalls are set up to take care of the security and blocking so hackers have a harder time getting onto routers and being able to access the computers that are more directly connected to it.
Other’s have mentioned fiber optic cable etc, but in reality it doesn’t really matter what physical media is used in any part of the path. Let me explain it a different way, using post office/mail as an example 🙂
Your local LAN is like your local neighborhood. There’s houses on streets. If you want to send mail to one of them, it’s probably easier to just walk on over and give it to them 🙂 Once you want to send stuff further than your local area though, you need something else.
So you get a post office! This is like your router at home. (note many routers these days are combo boxes and include Wifi and modem). In our analogy Wifi would be the post office using drones to send letters to you as you take a stroll around the neighborhood vs delivering to your house, and the modem you can think of as the post office changing “technologies”, going from local delivery vans to long distance 18 wheelers.
So you want to send a letter (“Pls give me Z webp@ge!”) to some guy on the other side of the world. The internet is very much like the post office in the way it works. 🙂
Your local post office isn’t very big, it would not be very efficient to have trucks leaving from your little post office to every other post-office in the world. So they setup centralized mail depot’s (hub sites if you will) in a select few large cities where they will send all mail. (In the “real internet” world, this hub site would be your ISP).
So now your letter is in the hub site. Just like you’d imagine, they look at the address on your message. If the destination is someone within the same country (aka ISP) great! They send it it the destination’s local post office directly. If the destination is in another country, they will look at the best way they can get that letter to that country. Maybe they have relations directly with that country, if so they’ll give it directly to them. If not, they talk to their neighboring countries to see which one knows how to get to the destination country, and when they find one, they give it to them. It may go through 3-5 different countries before ending up in the destination country.
(In Real world, once your message is at your ISP, your ISP will send it directly to recipient if the recipient is also a customer of your ISP. If they’re not a customer, they’ll look in their address book to which other ISP would be the best idea to give your message to. The ISP’s all talk together (automatically) so each one knows how to get to everywhere)
Getting back to our analogy, once your letter is in the destination country, their local post office system will ensure it gets to the destination.
Now, once of the things to take away here, is along the way your letter may have traversed quite a few hub sites, and traversed any number of different travel mediums. (plane/train/truck/etc). In the same way ISP’s have hub sites and can use different means of connecting together both the hub sites and inter ISP (aka inter-country in the analogy) traffic. It can go over microwave (wifi/radio towers), copper wire (dsl etc), and fiber optic cables. Fiber is the most common due to distance/speed/capacity so you find it almost exclusively on the long-haul links (think inter-city planes). 🙂
As said in other comments, we use satellites and cables across the ocean floor (submarine cables). Submarine cables are far more reliable, have lower latency (how long it takes to travel – typically measured in milliseconds), have higher bandwidth (soda straw vs. a fire hose), and are typically unaffected by adverse weather.
Here is an worldwide interactive submarine cable map: [https://www.submarinecablemap.com/](https://www.submarinecablemap.com/)
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