Why Do We Need IP Addresses? - Computerphile
Вставка
- Опубліковано 10 вер 2024
- A Computerphile viewer asked the question: Why do we need IP addresses when every network interface has its own Mac address? - I put it to Dr Richard Mortier; University Lecturer in the Computer Laboratory at the University of Cambridge
Machine Learning Methods: • Machine Learning Metho...
How Search Engines Treat Data: • How Search Engines Tre...
The Network Stack: • Network Stacks and the...
IP Addresses & the Internet: • IP Addresses and the I...
/ computerphile
/ computer_phile
This video was filmed and edited by Sean Riley.
Computer Science at the University of Nottingham: bit.ly/nottscom...
Computerphile is a sister project to Brady Haran's Numberphile. More at www.bradyharan.com
The concept is actually simpler than it sounds. It is just quite hard to find a really good explanation. Here is my try (work in progress):
MAC address is a unique name for each network card. You can use it to address one device in a crowd of devices so everyone knows who you are talking to. It is like standing in a group of 20 people and shout a name like JIMMY FUCK YOU. Everyone hears the message but only jimmy will be pissed off because it is clear you mean him ...
This system doesn't work in big networks like the internet though as you can not simply shout something every computer in the whole internet receives ... thus they need an address system there.
IP addresses are used for that address system. Instead just a name it uses a hierarchy like a post system (e.g. like Country, City, Street name, Number just more suitable for computers to understand). So instead of shouting around you write a neat post card add jimmys address and the content "FUCK YOU" and then you send it.
+devluz Yes, (disregarding bridges) Ethernet is a stack linear, whilst IP is a tree.
However, if we include Ethernet bridges, as hubs are almost gone, then your rather startling message to Jimmy will be much more private.
+devluz Really nice explanation :)
The analogy though 😂
Thanks 😀
3:15 best illustration of 2015
+PINGPONGROCKSBRAH Oh yes ... en.wikipedia.org/wiki/Vampire_tap
This is very cool and it's a joy to listen to Dr.Mortier who definitely knows very well what he's talking about.
However I believe an important point has been missed - which is that MAC is a local addressing scheme of certain technologies, such as ethernet and wireless 802.11. IP on the other hand is meant to be agnostic of the technology used to transfer data across networks that could be interconnected using multiple different technologies. Both addressing models exist at different layers or abstraction levels.
For example a 3G radio could be used by a device to implement a TCP/IP stack which means it understands and can be addressed by an IP but locally it may not have a MAC address because it uses a different addressing scheme. Even if I'm wrong about 3G specifically there are cases in which MAC addresses do not apply, such as direct dial up connections, ppp over atm, etc.
+Pedro Venda I actually think your phone/3G-stick and your dialup modem also have MAC-addresses. Even firewire connectors have MAC-addresses (dunno about USB).
+Scy Nah, 3G Modems don't have mac adresses. Most directly use PPP over a serial connection and then configure an IP link over that.
There is infact a standard (mostly used for high-speed 4G/LTE modems), which is emulating a network card via USB, that does infact have a mac address, but it isn't used for anything, it's not even unique and just there because an ethernet interface needs one.
+Scy Mobile data networks are complex things so there may be a level of abstraction and MAC addresses could perhaps be used. However it is not an IEEE802 network so if you were to tap onto the network and could see decrypted traffic you would not see anything similar to 802.3 frames.
Dial up certainly won't use a MAC and the same applies to a DSL connection on the phone network side -- most modems actually implement a transparent bridge to ethernet and it, of course, uses 802.3 frames and a MAC address. But if you use ppp over ethernet to connect to your ISP from a router separate from the modem or your computer, neither your computer/router nor your modem's MAC addresses even reach the PSTN side of the modem.
Excellent points.
+Pedro Venda
If you consider a MAC address as a physical address as opposed to strictly 'ethernet' then the DSLAM port number is the mac address for a DSL connection. You can treat the DSLAM/ MUX jumpers and copper pairs and DSL chip in the modem as wired components of a circuit. The first / last identifier in the packet network might be considered the physical address.
Dial up would again be the port on the dialin MUX as the rest is switched circuit (PSTN)
Of course this type of address might never make it out of the MUX.
I liked the analogy. My favorite one that I use when teaching people is to relate it to cars. MAC = VIN, and IP = Parking Space Assignment. IP subnets are then related to parking lots and how using your parking space number from Lot A may not work for Lot B, and ideally the entire time wherever you drive your car it still has the same MAC/VIN. :)
Whats VIN
If PCs have Mac addresses, why don't Macs have PC addresses?
+CNVideos eventually apple will begin a lawsuit against the world for unpaid royalties. XD
+CNVideos ... Must... resist... urge... to ... explain... :D
+CNVideos You! You there - I like you.
Now u rekt em m8
+CNVideos To answer that MAC is a acronym and stand for Media Acess Control
A 32 bit IPv4 address has structure. It is hierarchical. This is super important in understanding how packet switched networks function and how routing functions.
He knows the address of my router!
great video, I enjoy Dr. Mortier's explanations on networking, because I'm lacking in background knowledge on networking a lot and these videos are helping me to learn more.
I like how they sometimes trace a criminal from a police station on TV, and he appears to be operating on their own local network.
Here it used to be that phone numbers had the same structure to them, where a phone had a fixed known prefix of a city and an area in it of about 2-5 km in it (8000 or so phone number space). Only in the recent couple years a new regulation was put into place where customer was given a "right" to keep is phone number as he moves to another location. That seemed quite impractical to me.
+j7ndominica0 That's actually quite more practical since the fixed prefix came from technological restriction. Today with digital backends it's easier to just change the entry for the current number than go through the process of assigning one.
+j7ndominica0
Its the same as IPv4 in this video. When you make a call the telephone exchange could look at the first few numbers you type in and already route you down a line to the exchange that services that area code. Then as you keep typing the rest of the phone number that exchange is already listening to your next numbers to determine who in this area code you are calling and route you there, finally making that phone ring. Simply made routing calls much easier by not having to know where to route every single number at every single exchange.
Today the mountains of relays are replaced by a single computer with racks of phone line interface cards connected to it. The card listens for your dial tones, computer looks up the phone number and then sends your voice in digital compressed form down a single fiberoptic cable along with thousands of other peoples calls and peoples ADSL internet traffic and so on. So in the end its sort of the same thing as a skype call.
As a result a lot of ISPs are cutting out phone company middle man by giving you a internet modem with a built in phone line port so they can get your phone call in to the existing internet network tubes right at your house.
Do an episode on decentralized web solutions such as ipfs and zeronet.
To really explain, you'd need to talk about Layer 2 vs Layer 3 networking... but I guess this gets at least a little bit of the information across.
I have on queation is it posible to have a working phone of pc whithout a mac adres and stil acces the internet ?
that was a terrible description of IP against MAC addresses. Please do it again. Sequential MAC addresses could be on different continents never mind next door streets. This is important and needs explaining, if you could also do Layer 3 vs Layer 4 switching/routing it would also help. Ta.
+Martin O'Donnell where did they seem to indicate that sequential mac addresses *would* be adjacent physically?
Raymond D routing tables work with *ip* addresses, which are handed out to isps and then handed out to customers. this is what allows for the prefix matching tables.
Raymond D so it sounds like your first reply was intended for him then? be careful which "reply" you click on; it can cause a lot of confusion if you think you are talking to someone else.
MAC addresses are organized by the vendor that made the card and then a unique card within that vendor's grouping. So there is no logical organization to a group of them across a huge network that would be useful. IP addresses are organized by an addressing scheme that gets progressively more specific. Much more like an envelope address. You would first put all of the mail going to the same country in a pile and send it to that country. Then you'd sort that by the State/County/Prefecture/Province and then send them on their way. Then City, neighborhood, street, and finally house. It's the router's job to look at an IP and determine the fastest or most reliable path to its destination.
Why Do We Need IP Addresses? So we can get ddossed
+Fearl3sz Just imagine you only had mac addreses for global addressing. It would be impossible to escape a Denial of Serivce attack nevermind that online tracking would be extremely easy. We are currently at a stable Mid Point with IPv4, but quite likely as soon as we get to widespread adoption of IPv6 it will likely get worse again. This has partly to do with how NAT and addressing is often handled in IPv6. Yes totally random uncalled for comment XD
You do have a point there :P
+Walwalkn Wewnrkl Online tracking, because per default IPv6 encodes the MAC address into the really long IPv6 address. But there are specifications on how to not do that, but instead do something that makes tracking harder. The question is if devices and operating systems will do that. The easiest way of automatically assigning a IPv6 address involves the thing with the MAC address.
+Caffeine Code NAT is not needed in IPV6
+Fearl3sz "Why do we need a public unique identification?" would be my question rather. As we focus more on privacy and protection against DoS attacks we should get rid of unique identifications within the Internet.
We certainly already have technologies to use for networking so we shouldn't need these unique identifications.
For example Onion addresses, accessible through the TOR network, a string that identifies a web site to connect to it but is not usable to find out the real identity of the web-site owner.
Studying Computer Science at University of MInho in Portugal. I can only hope to have my masters at University of Nottingham.
+tipomartins FWIW I'm now at the University of Cambridge -- I left Nottingham at the end of last year. (Both are great for CS though!)
+Richard Mortier I say Nottingham but in reality I'd do anything to study pretty much anywhere anywhere in england.
+Richard Mortier Cambridge would also one of my preferable choices
+tipomartins I've (obviously!) no idea as to personal circumstance so apologies if this is just completely infeasible, but I'll say it in any case -- please do apply if you're interested!
If i get the chance I definitely will!
excellent, very helpful, thanks
nice explanation.
so it goes to "addressing"
Haha. Good to see Dr. Mortier recycling that old school printer paper
Considering Mr Robot (great users of the astu command) used an IP address containing a number over 255, I'd guess the malformed IP addreses in TV programmes and films are deliberate.
Why this channel doesnt have sub ?? it will great if this channel have one :)
So we could just use IP adresses insead of MAC adresses?
I like the way he explains things concisely, but he didn't really answer the question very well. As MAC addresses are software-assignable, is there still a reason to have both? Could we just remove MAC addresses? Are they in some way combined in IPv6 already? I think this is still not very clear to avg Joe.
+Bas van der Graaff MAC address are how devices talk on a local network. It's needed so that devices such as switches (which allow you to connect together a whole load of ethernet devices into one network), which work on a much lower level than things like routers, know where to send packets. For example, if you've got an IP packet for the outside world, it'll have some IP address not in your network as the destination. Your switch has absolutely no concept of "this machine is the router" (default gateway to be precise), and in any case, I can think of legitimate network configurations where different machines have different routers (default gateways), even connected to the same switch, so it would be very hard to build a switch that knows just from the fact that you're sending a packet to an external IP address exactly which port it needs to route the data to.
Instead, the IP packets are wrapped in Ethernet frames, which contain the address *on the local ethernet network* that you want to send the packet to, which will be the MAC address of the device that your computer has decided to use as a router. So the switch will either go, "oh, I've seen this MAC address talking on this port, I'll send it here", or "oh, I've never seen that MAC address before, I'll send it to all of the ports and hope for the best". In other words, it's some really simple logic decision a relatively low-level device like a switch can easily make.
So how does your computer know the MAC address of the router? It's relatively simple. The first time you try to talk to the router, your computer will look up its IP address by sending an ethernet frame across the whole network (to the special "broadcast" MAC address) called an ARP request, saying something to the effect of "everyone on this network: if you think you have this IP address, please respond to me with your MAC address". Then the router will pick this packet up and send back its MAC address, which your computer can then use to address the packet it actually wants to send.
I've simplified a few bits slightly, but I hope you get the general picture. Let me know if you don't understand a part of this!
Where the hell do you find that old-ass printer paper in 2015?
Well i didn't understand what is the difference between ip and mac
MAC addresses could have been structured the same as IP addresses to allow fast lookup tables on a global network. They're a legacy part of IPV4 no-one ever bothered to remove. Newer protocols like IPV6 & Bluetooth only use 1 address layer, consolidating the manufacturer data with the routing information into 1 big address.
+heroineworshipper But bluetooth is not designed for large networks of networks. And MAC addresses couldn't have been structured that way, not without making them variable at least.
So if I buy a laptop I have to tell the vendor where that laptop will be used so that the MAC address can be customized to where in the network hierarchy it will reside and I will only be able to access the Internet from that one location because if I ever take it elsewhere, no packets will find me there because my laptop's MAC address is not supposed to be in that part of the network? Sounds brilliant.
Oh and MAC address are *not part of* IPv4. IP runs *on top of* Ethernet which uses MAC addresses.
no extra bits :(
Zip codes and IP addresses work much the same. If the postmaster looked at a letter JUST addressed to your zip code without any street address he could get it to your local post office with the smallest amount database lookup time and information. (5 digits) Routers are processing brillions of frames (with packets inside) a second so IP table lookup and routing logic time (CPU clock cycles) is critical.
Let's think of it a little more creatively. Here is my interpretation of how you might get a letter to google using a pseudo-IP format.
940.043.AmphitheatreParkway.1600.CEO
The post master might look at the first 3 letters of the zip code and know that the 940 area is in california so he would route the letter to california's central post office (let's pretend that exists) and then the california post office (or router) would look at 043 and know to route the letter to the mountain view california post office and then from there that router would pass it on to amphiteathre parkway's router and then it would send it to your home router (1600 address) and then that router would pass it to the CEO's computer, tablet, phone, etc.
State and city information is already in the zip code, so that information is redundant.
MAC addresses ARE unique to the device like the social security numbers of the computer/phone/tablet. But routers can't build databases of everyone's mac address and know what network to send them to. The tables it would have to build would be extremely enormous, time consuming to parse through, and would have to constantly be updated as your device moves from network to network. MAC addresses contain no information inside of themselves that would clue a router in to where that device is in the world at any given time.
Afaik North Korean internet is one big ethernet. :D
I'd should this guy isn't speaking clearly. I'm kind of difficlut to understand his words.
Gotta love those Vampires
They probably use an out of scope IP addresses on TV shows/movies for the same reason they use dummy phone numbers.
He pronounces “route” like “root”. Is that correct? I thought it was pronounced like “out”.
+Šime Vidas It's "root" in British English, "rout" in American English.
+Muzer0 And in Australian English "route" is pronounced "root", but "router" is pronounced "row-ta".
+Šime Vidas would you draw a root for someone to get to the highway, or would you draw a rout?
no idea, usually I follow the big bill-boards when I'm in the US
+Šime Vidas In Canadian, British and Australian english it's root.
While I understand this stuff its still a lot to take in (especially when your drinking like I am right now), but I'd hate to work IT. Networking isn't my strong point when it comes to computers.... and I'd really hate having to deal with a "multi-home network" where you have many smaller networks on one big network (Like say a office building where each floor has their own network for each department that connects to a building wide network)... I alone hate dealing with complicated computer and networking problems, in that scenario, I'd rather quit or shoot my self then hunt down the problem
Peter Walker Nah, its just that some technical stuff never sinks in, then again I have ADHD so it makes comprehending some things rather difficult. I'd litterally have to be taught one on one every step of the way to learn something like this. Same thing goes for programing.
I always assumed they used the fake IP addresses on TV shows and movies for the same reason they use 555-5555 for a phone number--it doesn't/can't exist, so they don't risk people doing dumb things and trying to blame the studio.
Being able to change the MAC address is a privacy feature, nothing else!
Mac address never leave your home or business.
I would believe the ip's on csi were done deliberately if anything of the other computer realted stuff there made sense.
Besides, in the early days of networking, Ethernet was just one of many competing technologies. So not all of them necessarily had a Mac address. Other than that, I would say the analogy to the street address and the phone number should be reversed. That is, a street address is (relatively) fixed, so it is analogous to the Mac address. If you move to a different house within the same area, you can often keep your phone number even though your street address has changed. Similarly, if you get a new computer (and no longer use the old one), you can keep your IP address even though your Mac address has changed. So, the IP address is analogous to the IP address. You can also have several phone lines in your house, so the same street address may share several phone numbers. Similarly, a network card in the computer can have (and often does) several IP addresses that all go to the same network card. So, again, an IP address would be analogous to a phone number and a Mac address to a street address, not the other way.
+RustyTube But a street address can be used for directing people in increasingly fine steps (ie look at the city, then the street, etc.), whereas (at least in some countries where you can now port an old number between houses in different areas) phone numbers no longer allow you to do this to that great an extent. I agree the analogy isn't perfect because phone numbers are somewhat structured based on location, but you would, indeed, have trouble finding a house if all you had was the phone number, unless you had a big list of how each phone number mapped to each address!
+Muzer0 I guess porting phone numbers is only possible because of the computing power and database advances (SELECT XCODE FROM BCANX WHERE POTSID=). Originally it was a progressive crossbar switch system (shudder)
He doesn't explain the "structure" of an IP address. I think that would make it much clearer what he means.
+RogerWilco
I agree. If you mean the Network address as opposed to the host address. I think he may have been able to slip that in with an analogy that didn't confuse things too much.
dracs is that you?
i don't think hollywood ppl is THAT throught with their fiction, but i do think it's on purpose, to avoid other people with THAT address to have problem. (imho)
+Jerónimo Barraco Mármol That's pretty much it. None of the studios wants to be sued because their movie caused some group of smart alecks to hammer an IP address into oblivion.
While it may only be some poor schmuck's home computer, a random IP address may also invite some very unfriendly folks from a government agency. Better to use a nonsensical IP, or more often, one that routes back to the user's own computer or home router.
IT folks will roll their eyes, yet most people don't have a clue what 192.168.1.1 means, but it looks impressive. :)
But we have address blocks set aside for these purposes. Similarly to the 555 phone numbers there are 3 address blocks which are guaranteed to never be assigned to a computer accessible from the Internet: 192.0.2.0/24, 198.51.100.0/24 and 203.0.113.0/24. None of these 768 address will ever be used. Guaranteed.
And then there's the 240.0.0.0/4 block containing 268,435,456 addresses which will also never be used because of the deprecation of IPv4 (although, strictly speaking, this is not guaranteed).
Why not use these addresses instead?
You expect a scriptwriter, producer, or set designer to read RFC 5735?
Most of those folks are lucky if they work on a film that breaks even once in their lifetime. Details are often glossed over, even on films that seem to make money.
jb listener Well, they do use the 555 phone numbers. How have they not thought to themselves “if there are phone numbers which will never be assigned to anyone for purposes of fiction or examples, maybe there are some IP addresses set aside for the same reason”? From there RFC 5737 is only one google search away.
I just expect them to think about what they're doing. That's not too much to ask, is it?
***** Not to you or I, but seems to be too much for some.
Edit: Maybe a reflection of free intern-itis, too.
Why did we choose 128 bits for the address space in IPv6? Even with 64, we could give everyone on earth 2.5 billion IP-addresses...
+CelmorSmith The reason was hinted at in the video. With 128, there are enough IP addresses that we can give each home network a whole 64 bits of address space to play with, or even multiple sets of this if need be. This allows for a lot more flexibility in the assignment of local addresses, and lets you do clever things like having a computer choose its own address based on its MAC address and not having any chance of conflicts (whereas just having 32 bits to play with, remember once you've taken 32 bits for the network, doesn't have enough space for this). This makes it harder to bruteforce IP addresses. This also means you can do nice things like moving to a new network and half of your address still staying the same, making setting certain things up significantly easier. No longer do you have to have a central server managing who has which IP addresses (though this is still an option if this is how you like to set up your network, of course). It's all quite well-designed, really.
And it's not like an extra 8 bytes per IP packet is really going to make a whole world of difference.
Muzer0 I thought of the possibility of not having the need for a DHCP server in every network (except where IPs have been set manually) because you could even take a random IP and most likely it has not been used yet.
What I don't know about IPv6 though is how a network device configures an IPv6 address for itself, more specifically what it sets the first few bytes of the address to, I figure it uses a default value there that defines the IP address as belonging to a private network, like a 192.168.*.* in the case of IPv4. I haven't read into IPv6 that much but it definitely makes generating a IPv6 address for itself by taking the own MAC-address and have the network device just being able to communicate on a network without having to rely on services that run on the network. I guess there also has to be a default IPv6 address it chooses for it's default gateway though.
+CelmorSmith What you've described is the "link local" system. Every v6 interface gets a link local address by default, automatically generated, which start with fe80. This actually has an analogy in v4, except that you generally only see the addresses when there aren't any DHCP servers around so it's less obvious it exists; they start with 169.254. These systems are mostly designed such that an arbitrary collection of computers can form an ad-hoc network with each other with absolutely no configuration, but it's unlikely (and not a design goal) that such a network will be able to talk with the outside world without extra configuration.
However, v6 has another system that to my knowledge has no v4 analogy as it would be relatively impractical in v4. The IPv6 Router Solicitation protocol allows a router to simply advertise to all connected devices, "this is the first 64 bits (known as the prefix) of the IP address of this network. Do what you like with the other 64". Then any device can use the remaining 64 bits to generate its own IP address, and then use this with the 64-bit prefix advertised by the router. Clients use this to produce one predictable address based on their MAC address, which can then easily be used to connect into the device (since it's predictable and shouldn't ever change when that device is on the same network), and also (with modern "privacy extensions" which many/most? OSes now support) produce many unpredictable addresses that change regularly for privacy reasons, which are the ones that outgoing traffic comes from.
This system allows you to have a basically self-configuring network. You just need to tell the router to start advertising the prefix, and then every client will automatically get a public, static, IP, but one that is relatively hard to brute force. You should obviously not rely on "security by obscurity", and should still set up firewalls in lieu of NAT. The idea is that if you set up your firewalls correctly (and even on OSes like Linux, firewalls are easy nowadays), you'll be just as secure as on v4, without the need for NAT or the inconveniences of not having a public address. Having finally got v6 set up in my house about a week ago, I'm amazed at how liberating it's been!
+CelmorSmith The argument for only giving 32 bits for ipv4 was that we'd never have more than 4 billion addresses. We don't want to make that mistake again.
Muzer0 Thanks for the explanation. Amazing how much of how IPv6 works I could figure out myself without reading into the matter.
Most of consumer devices that use the internet protocol in some way are already compatible to IPv6, only the WWW needs to get completely compatible too, there are still servers that you can't connect to with an IPv6 address and "adapters" aren't 100% reliable, also many ISPs still have network gear in service that wouldn't be compatible with IPv6. At least that's what I heard as a reason why we haven't completely switched over yet.
Say what???
You buy blocks of MAC addresses from the IEEE... so, as a manufacturer, you give each device you sell a unique MAC address. When the device first wakes up on the network, it advertises itself by giving its MAC... the gateway doing the DHCP gives it back the IP it wants it to use (unless it's doing static IP)... and the gateway is exposed to the WAN/Internet. Your device can see out, but nobody can see in, unless your router/gateway exposes your device to the WAN... and it will give a different IP address than the one you see locally. That's why MAC addresses don't work for LAN/WAN... they're not heirarchical, they're only a hardware globally unique identifier (GUID). The IP's are set up, top to bottom, as heirarchical, and are meant to be fluid at the local level.
MAC addresses are NOT unique. Manufactures starting re-using old MAC addresses years ago. They only need to be unique to your local network. They are not world unique.
We had a situation where a hardware maker sold us dozens of devices with the same MAC address. What a mess that made!
Interesting
34638a Not like your comment.
"rooters"
I love how he trys to explain it as if it was conceived before they started implementing. Much like all great technologies it was an evolution of feeling around in the dark. Not a grand scheme as this "professor" professes, which is yet another point of humor for me. Exactly how much do the suckers (err, I mean students) pay to matriculate at Nottingham u?
Muzer0 conceived yet changed after implementation is not following a predetermined plan. Which was the point, you must have missed that. So my statement about feeling around in the dark still stands and with even more support thanks to your misguided attempt at introducing confusion and false statements to the topic.
He was professing knowledge of something he doesn't have a full grasp of. Please note the quotation marks around the word professor.
Make sure you fully comprehend what you read before responding in the future, it will save everyone time and you get the added benefit of keeping people in the dark about how ignorant you really are on a given topic.
+nunya biznez I don't understand where my comments are going, but let me try again. Your argument makes no sense. Why would the fact that a person hasn't explained every single minor historical change between the original spec and what we have today, however irrelevant those are to the general point of the video, mean that clearly he's explained it badly? What?
6 years have passed, but it's time for you to know: this isn't a fully comprehensive course, not even a lecture.
I'd say this guy doesn't speaking clearly. I'm kind of difficlut to understand his words.
So why do we have a MAC address on a PC? xD
+RedStefan It's short for: Media Access Controller. It's been around for longer than macs have been around.
No explained particularly well :/
First
What a load of gibberish!
+tariq sherwani This channel is intended for people who have a decent amount of knowledge about computers. You need to actually know how to do something more than post a UA-cam comment or run a "Hello World" program in Java for this to make sense to you.
***** I agree but for someone who is not literate in technology it might be hard to understand.
Private Pecker Not super easy? Maybe. But hard? Most of the things on this channel are explained very simply. And if you still don't understand something, well, you're watching this on UA-cam; Google is just a click away.
It hurts when IP
I agree with everything said, except for the unfortunate pronunciation of rooter instead of rauwter.
Rauwter is just as incorrect as leaving out the u of colour.