Cabling Devices | Network Fundamentals Part 2

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.