in this video we're going to have a look at cabling and Wi-Fi the ethernet protocol and network addressing hang around you'll love it when it comes to connecting devices there are two options wired and wireless wired connections have been around since the beginning of time that's the late 1960s as far as networks are concerned a wired network uses cables to connect devices together wireless technology in general has existed for a long time think of radios and mobile phones her example the wireless technology that we think of most with networking is called Wi-Fi which has been around since the early 1990s cables can be copper or fiber copper cables are usually cheaper and are very common for short distances data is sent over copper cables using electrical signals this means that they can be affected by outside interference I'll explain why this happens a bit later fiber cables are made of strands of glass data is sent through the fiber in the form of light fiber is more expensive but is really good over longer distances also he's not affected by outside inference a wide land uses a protocol called Ethernet remember that a protocol is a set of rules that devices in the network agree on Ethernet is made up of a lot of different parts some of these parts describe types of cabling and the speeds as they run out other parts describe how the data should be formatted and sent this is called media access control the reason Ethernet is layered like this is so devices with different cables and different speeds can all still communicate imagine a workstation that has a one gigabit connection to the network it wants to send data to a server that has a 10 gigabit connection the workstation prepares a message it formats it according to the media access control rules then it prepares to send the message according to the physical rules that it has to follow when the server receives the messages it decodes it at the physical layer the message that is left is the same as it was at the station smack layer as you can see even though they have different connections the hosts can still communicate because of this layering system Ethernet was designed by a group called I Tripoli I Tripoli have created many different standards for different technologies all of their standards have a code number standards that start with eight zero two are used for lands Ethernet for example is arrow two three remember how Ethernet is a group of standards each of these is assigned one or two letters for example tanki Ethernet is 802. 3 a n if you'd like to see a full list of Ethernet standards have a look at the Wikipedia page on I Triple E arrow 2. 3 coats like arrow 2.
3 a and can be tricky to remember so each of these physical standards have friendly names which are a bit easier to understand for example at O 2. 3 a n is also known as 10 G base T this gives us a bit of a hint about what the standard is the 10 G refers to the speed of the connection in this case it is 10 gigabits per second base is short for baseband this means that it uses a digital signal the alternative is broadband which uses an analogue signal the T means that this is a UTP cable I'll explain what a UTP cable is soon you might see other cables here like LX which refers to a type of fiber optic cable electrical cables use electrical signals these are a pattern of ones and zeros the receiver needs to decode this pattern the pattern is called an encoding scheme to send electrical signals a circuit is needed this means the electrical cables need to contain several wires the most common copper cable is called unshielded twisted pair or UTP modern UTP cables contain four pairs of wires where each pair forms a circuit electrical signals over copper cables can be disrupted by interference think back to high school science for a while do you remember that electricity and magnets are related electricity flowing through a copper cable creates a magnetic field a magnetic field and a copper cable can create electricity the problem is that a pair of wires running parallel create a small electromagnetic field the field from one pair of wires can affect the signal on another pair of wires this is called crosstalk UTP eliminates most crosstalk by twisting the pairs of wires together each pair is no longer running in parallel so they don't generate the field if you can find an old network cable that you don't need cut the end off it and strip back the plastic around the outside you'll probably find four pairs of wires depending on how all the cable is there may also be a plastic core or a piece of string they're color-coded so each pair has a solid color and a striped color for example one pair will have brown and striped brown wires now I said that you will probably have four pairs there wasn't always four pairs though older ethernet standards such as 10 base T and 100 base T only needed two pairs but to achieve one gig and 10 gig speeds all four pairs are needed not only other different Ethernet standards but the cable itself has different standards you will hear of terms like category 6 or simply cat 6 the category defines things like the number of pairs in the cable the thickness of the wire and how tightly they're twisted for example cat 2 has only two pairs cat six has four pairs cat six has thicker wires than cat five and so on sometimes there'll be an e or an a at the end of the name cat5e and cat6 a are examples of this this is where the original standard has been improved upon newer standards support better speeds over longer distances for example you can use a cat 5 cable on a 100 Meg network but if you want to run a gigabit network you need at least cat 5e if you want 10 gig cat 6 is okay up to around 55 meters but if you run cat 6a you can have a 10 gig link that works up to a hundred meters each newer standard is backward compatible with the older technology for example you can use a cat 7 cable on a 100 Meg link your cable has a connector at both ends this is called an rj45 connector this is the part that you connect to your network card or switch port this connector has eight pins these line up with the eight wires inside the cable the wires need to line up with the correct pins that's why the Y's are color-coded there are different color schemes you could use this one here is called 568b a standard UTP cable will match the wires on both ends this means that pin 1 connects to pin 1 pin 2 connects to pin 2 and so on this is called a straight through cable as the wires go straight through from one end to the are some pairs are useful transmitting data and others are used for receiving for example pair 1 transmits while pair 2 receives you'll see here that I've used the terms Rx and TX these simply mean receive and transmit when you connect a host to a switch the switch to something very clever it knows that pair 1 is used for transmitting and pair 2 for receiving so it does the opposite it uses pair 1 to receive and pair 2 to transmit so when the host sends on pair 1 the switch receives on pair 1 the same logic is used on pair 2 the key point here is that a straight through cable is used to connect a host to a switch but what if you want to connect a host to something is not a switch perhaps another host or a router the pins no longer line up correctly they are both using the same pairs for receive and transmit so instead we need to use slightly different cables what we do use is a crossover cable this swaps the pairs at one end so transmitted lines up with receive once again this is also the type of cable you would use if you want to connect one switch to another switch now you're probably thinking that's a pain now I have to worry about two different kinds of Ethernet cables and making sure I use the right one at the right time to save you from this dilemma we have a technology called Auto mdi-x a device of support although mdi-x can detect if the wrong cable is used it can then logically switch the functions of the pins so they match the cable the 100 base and newer standards support auto mdi-x so in the real world you don't have to think too hard about the cable you use in fact crossover cables are getting pretty rare these days if you're going to do a network exam though you should still remember the difference between a straight-through and crossover cable when we get to 1,000 base though things change this uses all four pairs of wires while older standards only required two there are two ways this can work which are called 1,000 base T and 1000 base TX the TX standard uses two pairs for sending and two paths for receiving you will need cat6 cabling or higher if you want to use this standard the T standard uses all four ports for sending and receiving it's a bit different to everything we've discussed so far but it works and you only need cat 5e to support it in the interesting requirement in both thousand base standards and newer is that they require Auto mdi-x support the alternative to copper cabling is fiber cabling fiber cables use strands of glass which are sometimes called a pipe or a core a light pulses down the fiber strand which is received at the other end it works like the example here which shows a laser following a stream of liquid the pulsing light is another way to encode information fiber is often used between networking devices like routers and switches it may also be used in servers I've never seen workstations use fiber but I guess anything's possible I'm going to take a quick detour and talk about something called duplex devices need to both send and receive data UTP cables can send and receive at the same time if both ends of the link support this it's called full duplex sometimes a device will not be able to send and receive at the same time instead it will send for a while stop and then receive for a while this is called half duplex these devices can still send and receive but they can't do both at once full or half duplex is determined by the cabling that's used the capabilities of the device at both ends of the link and the software configuration there are two different ways that fiber can be used first you can use single core only this operates in half duplex mode as it can't send and receive at the same time the other option is dual core this is full duplex as one core is dedicated to sending and one is dedicated to receiving be aware though there's easy to get the cause mixed up if you connect the fiber and it doesn't work try swapping the cause at one of the ends the enterprise network will mostly use dual core fiber this means between switches routers and servers service provider networks like your internet and when providers offer new single core there you need to be aware that there are two types of fiber these are called single mode and multi mode they may look the same but they are different because of the types of light they use multimode which is known as MMF uses a LED light this is not a particularly powerful light so it is used over shorter distances say around 500 meters or less which makes it useful to connect devices in the same building the LED light is also cheaper to produce making multimode fiber the cheaper option single mode fiber or SMF uses a laser light this makes it more expensive but it is capable of much longer distances you can easily get two kilometers or more depending on the hardware you're using you would typically use single mode fiber between different buildings or your service provider may run single mode fiber into your building to give you an or internet access even though a fiber-optic cable is made of glass he's still flexible you can bend the cable well at least to a point the fiber cable has a maximum bender radius the Bend radius is how tightly the cable can be coiled up before attenuation occurs attenuation is where the signal is degraded or lost this does not necessarily mean that the cable won't work but it won't work well the manufacturer of the cable should be able to tell you what an acceptable Bend radius is there are different connectors that the fiber cables may use quite a few in fact when you remember that fiber is not just for networking the main ones we see in data networking are called LC and SC LC other smaller connection types which are usually used on switches and routers it's common to see these in a dual core configuration but they can be separated into single core SC connectors are older and larger they seem to be less common these days they're more often seen in a wiring closet some switches will have a special port that looks empty some switches are made up entirely of these ports these are made for installing a transceiver module these can be used for different purposes but basically they are so you can mix and match the top of cabling you use different transceivers support a different cable type this includes single mode and multimode fiber some transceivers will support both but they also support different speeds like 1g or 10g as well as different cable lengths for example a long cable run of 40 kilometres will need a more expensive transceiver than you will need for a one kilometer run the reason that some of these switches have many of these ports is so you can mix and match which transceivers you use for the job you can even use an rj45 transceiver for when you want to use UTP copper cable for that matter you can even get a special copper cable with SFPs built in it's called the twin x cable but that's another story the our method of communication is wireless aka Wi-Fi it doesn't use cabling of course but I should mention it quickly anyway wireless networks use access points these devices are like a switch for the wireless network whilst devices like your phone or laptop connect to the access point the access point may also connect to the wired network this is how wired and wireless devices can be in the same network Wireless is a good way to connect end-user devices you wouldn't normally see a server or router connected to an access point Wi-Fi does not use the arrow 2.
