Understanding Switches

so hello again as you know I'm Eli the computer guy here for everyman IT today's class is understanding switches so so switches the things that that that connect your network together you know these connect your computers to the network these connect your printers to the network your servers to the network your routers to the networks etc these things called switches so we're going to go over the basic concepts of what switches do and and things that you should think about when you're deciding what switch to buy I've been very surprised a lot of consultants running around now basically all they think of a switch is they think this is the thing that all the computers plug into they they don't think about anything else they don't think that these little things actually have brains in them that that there are these things run protocols that they that you do a lot of fancy cool stuff they just go plug a computer into it so so this class is going to be an introduction explaining to you all the different things that switches do again switches are the core of your network everything on your network connects to a switch at the end of the day so if you buy the wrong switch or you install the wrong switch or you don't know how to troubleshoot switches that's that that's a real real real problem so so give me a second to set a few things up and then we'll go into the class understanding switches so the first thing that we need to do is kind of define what a switch is you know talk about what is a switch and why is it important the best way to tell you why switches are important is to go back to the predecessor of the switch which was called the hub the hub was basically a way to split Ethernet signals the same way that you have a cable splitter in your house to split your TV signal to multiple TVs in your house so basically you plug you know the main the main cable connection into a splitter and then you split that one connection off and do it to five different TVs basically that was the same thing with hubs so you had a hub let's say it was a four port hub 2 3 4 and then you had 4 computers connected to this one single hub so these computers could now communicate with each other and they could share out a printer etc the problem with the hub is this is genuinely a splitter any communication that came in to this hub was sent out on every single port that was on the hub so if this computer was trying to communicate to this computer over here when it's in a signal into the hub that communication was sent out to the other two or five or 10 or 50 other computers that were connected to the hub now the problem with that is simply how the ethernet communication standard works a Ethernet uses something called a collision avoidance collision detection in order to send packets so so hopefully at this point if you don't understand basically Ethernet sends all communication in what are called packets so so if you were sending a document to another computer that document gets divided into a million different packets and all those million different packets are sent over to the computer that you're trying to communicate with well what happens is if this computer here is trying to communicate to this computer up here well it'll do is it will listen to the net so we'll see if anything is being communicated on the network if nothing is being communicated on the network it assumes that the network is available and then it starts sending packets up to this hub and then the packets get to the computer that it's trying to go to but with a hub you're also sending the exact same packets to every single other computer that is connected to the hub so that ties what first that ties up a lot of bandwidth well what happens to this this is the bigger problem is let's say you have two computers that are trying to talk to two different computers on the network so this computer is trying to talk to this computer so one is trying to talk to two and three is trying to talk to four right so one and three are going to listen and they're they're going to listen to the network and see if there's any communication going on in the network if there's no communication going on they will try to talk to the computer that they're trying to talk to here's the problem if if computer one and computer three try to talk at the same time they're going to send their packets at the exact same time somewhere in here there's going to be a collision so the path so threes packets and ones packets are going to collide because only only one computer can communicate at a time on a hub so if three tries to send packets at the same time that one tries to send a packet those packets will collide with each other Ethernet standard uses something called collision detection so when that collision happens both computer one and computer three will hear that collision they will then wait a random amount of time and then start trying to communicate again so so let's say if there's a there's a collision you know let's say computer one will randomly wait let's say 0.5 milliseconds to send out a new packet and number three will you know wait point six milliseconds to send out a packet so hopefully when they go out to send packets again there will not be a collision the problem is as you start scaling up this hub and you more and more and more and more and more computers all trying to talk these collisions start happening more and more often so so you know there's more and more you get 20 computers all connected to a hub there's more chance that there will be these packet collisions if there are other packet collisions then the computers that are trying to talk you know all randomly wait a period of time this can all culminate and do something called a broadcast storm we're basically all the computers on the network are trying to talk at the exact same time they're all getting collision signals they're all waiting random amounts of time but but then so let's say to transit sites talk at the same time as one so there's a collision well one will randomly wait let's say a second to talk but when it tries to talk force trying to talk so all these computers they're trying to send data only one computer at a time can send data and so that there's these collisions when the collisions happen the computers reset you know they're they wait a random amount of time and then try to send again but again if too many computers on the network are trying to talk you're going to continuously keep getting all these collisions and basically the the network comes to a standstill it really does so basically the main thing the predecessor of the switch was this thing called a hub a hub literally all it does is split the network signal and again the problem with that is is only one computer at a time can talk if you have multiple computers trying to talk at the same time it creates something called a broadcast worm it is just a complete and utter mess so so hubs are bad I have seen some modern networks still have hubs on them and people wonder why the network doesn't work worth a damn that's why if you have a hub on your network if you if you pick up if you pick up the little device that looks like this and it says pub on it anywhere if it says hub throw it in the trash go out and spend 50 bucks on ass which we'll talk about in a minute but basically hubs are utter and complete garbage they're they're worthless they were obsolete ten years ago so so don't use a hub now what a swig does is let's say we have this 4 port switch and again you know we have the computers connected off of it so if 1 2 3 4 so we have these 4 computers connected off of this hub or this switch why the switch is useful is because let's say computer one is trying to talk to computer for what's going to happen is when computer 1 tries to talk to computer for the first time that those packets are going to get sent to every single computer on the network but what's going to happen this time is this switch has some brains to it so the switch is then going to learn where computer 4 is so basically computer 1 tries to talk to computer 4 when the packets come from computer 1 the switch goes oh I see computer 1 is connected to port 1 so we know that now when it sends the packet out you know trying to find computer for it'll send the packets computer 3 computer 2 and then up to computer for computer 3 in computer 2 will not respond because they don't care it's it's not meant for them computer 4 will go oh thank you for those packets and it will send an acknowledgment that's kind of how at their networks when it sends that acknowledgement the switch will then go oh I see computer 4 is connected to port 4 so now in the future whenever computer one tries to communicate to computer 4 instead of broadcasting out on all the ports on the switch the switch will only send the packets to computer 4 so it knows where computer 4 is so computer 2 and computer 3 will no longer hear that traffic now again the nice part is if computer 3 then decides to talk to computer 4 when it sends a packet the switch learns oh I see computer three is connected to port three it already knows where computer four is and so it only sends the information out to support for see how that works basically now the switch starts learning where all of the computers are connected to the switch so you know whatever port they're connected to and now though only now the switch will only send data to the appropriate port so that means computer one can be talked in a computer for computer three can now be concocting computer two because inside the switch you know it creates a little roadmap so so when computer one's talking to four it just goes to four when computer three is talking to two it just goes to two and so now these computers and these communications can be happening at the exact same time so you know computer three can be talking to computer two while computer one you know goes off and tries to do a print job this was impossible to do a back with with hubs because you know like I say only one computer could communicate at any one time with switches now you know you can have 50 computers all carrying on conversations at the exact same time very useful now what we should talk about with this is layer it with a switches we talked about the OSI model before well switches reside at layer 2 of the OSI model the reason they reside are they're said to reside at layer 2 is the way that that the switch learns where the computers are connected to the switch if this it does something called discovering and the MAC address of the device that's connected to it so every single networking device that is ever created has a MAC address every single one so switches have MAC addresses routers have MAC addresses printers have MAC addresses if they have a network card built into them all network cards have MAC addresses so if you have a laptop computer your wireless card on that laptop computer has what's called a MAC address and the hardwired the the rj45 plug has a MAC address all networking devices have Mac process basically MAC addresses look like 0 0 1 d 2 4 . i know 6 8 this isn't a real one this is what MAC addresses look like what you should understand you just understand about MAC addresses all MAC addresses are unique the first half of the MAC address is an identifier for the manufacturer of the equipment so let's say Nortel Networks puts a different beginning to their MAC address it in Cisco then you know a seuss or any of the other companies and then the the end of the MAC address is basically like a social security number so you put basically the manufacturer first and then their little social security number or serial number in the back as you can see from this so this is a this is a managed switch and this has a MAC address on it so all networking devices have MAC addresses on it so basically to just to understand is the switch figures out the computers by their MAC address uh we're going to a more complicated class later with hacking and stuff where there's something called MAC address spoofing and all but you just understand that switches care about the MAC address of the computer or the device that is connected to it so so yeah so as I said basically you know with hubs the signal went out and we went out to every single port on that hub problem was is if there was a collision on the network all the computers that we're trying to talk would randomly you know wait a period of time and then try to communicate again if you put too many computers on that hub that means all the computers are trying to talk at the exact same time and it's it's just a complete mess what switches do is again the first time a computer tries to communicate to another computer on the network when the first computer talks to the switch the switch then learns where that first computer is located it then sends out the packets to every other single port on that switch when the destination computer responds then the switch learns where that destination computer is again so the first time you know computer one as it can talk to computer for everything gets broadcast out computer for response and now the switch knows where computer for is if computer three tries to talk to computer four when it comes down the switch will learn where computer three is located and then instead of broadcasting out to everybody it will only brought it will only send the packets up to we're already knows computer forest it's pretty simple I think so that that's that the basics of what a switches so one of the first terms that you're going to see when you're going to look to buy switches from newegg.com or wherever you're going to buy switches from is you will see managed switches versus unmanaged switches so so what does this mean basically you have two types of switches remember switches have have a little bit of brain power in them so you know like I said the hubs the hubs were completely dumb all the hubs did was act as a splitter and you know the exact same data goes out on every single port switches have a little brain power to them basically the idea with the manage diversity unmanaged switches is how much you can configure the brain power inside the switch so most the switches that you're going to buy if you go down to Best Buy or sucker you spend 50 bucks or $300 on a switch these will be unmanaged switches so like this little guy here this is a Linksys gigabit I know what is it 8 port unmanaged switch basically with this everything inside of this is completely and utterly automatic there is a little bit of Brit bit of brain power but I can't I can't do anything with it basically I plug it in and if it works great and if it doesn't work I throw it away there's just although there's brain power in it there's nothing that I can configure basically you plug it in and if it works it works if it don't work it don't work and that's all there is to it now when you get to the big-boy world this is what is called a managed switch so managed switches allow you to actually go into the switch and set configuration so so in a minute we're going to talk about all the different types of configurations that you can set but basically a managed switch allows you to set those configurations things like speed duplex VLANs quality of service or class of service all of these things a managed switch allows you to go in and to actually play with it's just very important that you understand this because uh if you need a managed switch anybody an unmanaged switched and that that's a problem managed switches are going to be a lot more expensive than unmanaged switches at least twice the cost but but depending on what you're doing it really might be worth it so you know a lie saying the next sections are going to be talking about things like V lambs quality of service if once you listen to them if those things are important to you then you need to buy a managed switch if at the end of it those things are not important to you an unmanaged switch is probably fine now the first four settings or configurations that we can talk about on a switch are basically the speeds and the duplex setting so what is this well if you pick up place a normal switch now you will see that all the switches will at least be 10 by 100 what this means is that they can work at either 10 megabits per second or 100 megabits per second so so the first Ethernet standards the first you know computers they used Ethernet were 10 megabit per second connection so they could only transfer a maximum of 10 megabits per second then they came out with newer faster computers that could do a hundred megabits per second well basically to make sure that switches were backwards compatible with the old stuff they then made switches that could automatically be set between 10 megabits per second or 100 megabits per second so if you had an old 10 megabit per second computer and you plugged it in it would be able to communicate on the network if you plugged in 100 megabit per second computer it would be able to communicate on the network pretty simple and then of course we now have that thousand mega bit or the gigabit per second connection again the exact same thing so if you're looking at a switch and it says 10 100 1000 that means it's able to support 10 megabit per second connections 100 megabit per second connections or 1 gigabit per second connections nowadays you know like I say 2010 get here real close to 2011 I have no idea why they still have 10 megabit per second connections I'm not sure I've ever in my 12 years seeing a 10 megabit per second connection but they still have it on here now what you should realize is that when you're dealing with unmanaged switches like this this little switch will automatically try to detect you know what speed is coming through so it will automatically detect if it's a 10 megabit per second 100 megabit per second or a gigabit bit per second connection speed and then it will automatically set the port to that speed if you're using a managed switch you can you can go in and you can actually configure the the port be whatever speed you want so if you wanted to be 10 megabits per second you can do what is called hard coding that pork to be only 10 megabits per second or to be 1 gig per second where where we have our server that provides these these video classes to you guys in order to make sure there are no problems on their network on the data centers Network we hard-coded our our switch and our server to one gigabit per second connection speed the one thing that you do have to realize is if you leave all this stuff automatic you know something sometimes automatic stuff does this flaky thing so maybe you have a hundred megabit per second connection a computer connected to this but it'll for some reason detect that it's only 10 megabits per second that can be a real problem that's a nice part with managed switches is if you know that you have a hundred megabit per second computer connected to the switch then you can hard code the switch and the computer you just adjust to be at the 100 megabit per second now the other thing with speed is something called duplex again almost everything in the world is now full duplex but we should talk about half duplex them in case you ever run into it basically what half-duplex and full-duplex means is whether or not you can talk and listen at the same time or whether the computer or device can talk and listen on the network at the same time half duplex equipment can only talk or listen at any one moment so imagine half duplex at like a walkie-talkie so when you have a walkie-talkie you can either talk Roger Roger Jim Niner or you can listen Roger Roger I'm not you cannot talk and listen at the exact same time now if you have a cell phone that is called full duplex because you can talk and listen at the exact same time the same is true with networking equipment again I'm not sure what networking equipment ever used half duplex I'm not sure I've ever seen it but apparently there was networking equipment out there that did use half duplex all modern networking equipment uses full-duplex so so computers in a laptop servers routers etc they can talk and send information at the same time but you should realize that you can either have half or full duplex on these little little switches so this is one thing like I say all of this stuff gets configured on unmanaged switches all this stuff gets configured automatically so sometimes that's why it's a good idea to reboot your little switch because sometimes things get messed up in the brain I went to a a switching troubleshooting class a couple years ago and they showed how you can have two 100 megabit per second computers and because of automatic problems in the switch you can actually have them communicating at 56 kilobits per second because there is this whole mess where they laid it out but basically if if the switch thinks that one computer is at 10 megabits per second and that the other computer is only talking half duplex it just can cause an entire mess so this really really can't happen in the real world that's why you should should reboot your little switch every once in a while now with the manage switches so these guys you can either I say you can hard code the switch boards or you can leave it automatic so most people do still leave all the ports on their switches automatic but if you're having specific problems like I say your server isn't communicating properly etc you can hard code the port on your switch to be 100 megabits per second full duplex and then you go to the server and on your server you hard code for 100 megabits per second full duplex and a lot of times that will actually fix a lot of problems now the final thing when we're talking about speed and duplex and all that is something called the backplane or well it used to be called the backplane when I was doing research for this class apparently they've come up with new words for it but basically the backplane as I learned it is what connects all these ports together so so each one a sports let's say it's 100 megabits per second or 10 megabits per second etc well the backplane is what allows all these different ports to communicate with each other the big thing you just have to note when you're going out to buy a switch is what the total capacity of the backplane is so so basically if all these these computers are trying to talk at the exact same time can the backplane can the overall switch be able to handle that communication so I was looking at a Cisco router and it was a 48 port Cisco or Cisco switch 100 of 10 100 megabit per second the backplane could handle up to 32 gigabits per second of communications so that meant that basically every single port on that switch could be communicating at the exact same time this is a problem like I say is if you go out and try to buy you know cheap switches or you know no-name brands all the port's maybe be 10 100 megabit per second or even gigabit per second speed but the backplane the brains what connects all this together if the backplane can't handle communication from all those ports simultaneously then you have problems so that's what the buck backplane is so basically with speeds you have 10 10 100 or you have 10 100 gigabit per connection speeds basically you know it is what it is then you have full duplex and half duplex communication full duplex is can a device talk and listen at the same time half duplex is that it can only it can talk or it can listen and then finally the backplane the backplane is really important like I say once you start getting the enterprise environments or once you start you know once you start having clients you know 50 computers all connected to a switch remember if that backplane doesn't have enough bandwidth then the computers are going to have problems so so that's the basics of speed so also we talked about speed the next thing we need to talk about are your trunk ports on the switch so so a lot of times these little guys don't have trunk ports but if you buy the more expensive like I say the manage switch you will have trunk ports so you have your normal 48 ports that you connect your computers your wireless access points your printers etc into and then you will have trunk ports what happens with these trunk ports is basically if you connect multiple switches together you want to connect them together through the trunk port what happens with this is when one computer tries to talk to another computer you know on the network the switch will look to see if that computer is on the same switch if not it will send the the data to the trunk port to go to the other switches that the switch is connected to you know if you're dealing with Cisco or high end switches these trunk ports will actually be fiber optic so if all these computers are trying to get out to the internet or trying to get to a to another switch on the network this this D BEC connection here can actually handle up to 10 gigabits per second of connection speed so basically with a trunk port is it's a way to connect multiple switches together those trunk ports can handle much more data because you may have all 48 ports trying to get through something that's on that trunk line again almost all switches have it sometimes these these little guys these unmanaged switches will not have it but sometimes they will have it and so if you just want to make your life easier if you want to cause less network problems always look and see if it has a trunk port if it does only connect the switches using that trunk port it will just make life a whole buggies e'er now the next thing we need to talk about our VLANs v LAN or virtual LANs virtual local area networks now you can only set up a VLAN on a managed switch so you know a Cisco switch or a high-end switch that you can actually go in and set configurations so what a VLAN allows you to do is it allows you to actually separate the ports on a switch in two different networks so let's say you know we talked before about MDF sand idf's and that uh was it physical network segmentation class but let's say you have multiple network cabling all running back to one idea for one main you know wiring closet but you don't want those networks to talk you know that you want them to be entirely separate this this comes into play and nowadays with with what's called convergence you know now that we're using voice over IP telephones and we're doing using surveillance systems and we're using computers we may not want those devices to be able to talk to each other at all we want to put them into their own little walled gardens so they do not communicate you know you don't want some virus getting on your computer network that is somehow able to take over your phone system that would just be a bad idea so what VLANs allow you to do is it allows you to separate the ports into different virtual LANs so that the computers on these virtual LANs cannot in any way shape or form talk to each other so if you have pcs on this virtual LAN and you have telephones on this virtual LAN and you have surveillance systems on this virtual LAN although they're connected to the exact same physical switch because you divided the ports into different VLANs they cannot communicate to each other at all so you can't hack into this you can't be sitting on computer here and hack into the telephone system you can't hack into the surveillance system as for as everything is concerned these all these systems are connected two entirely different networks now something that confuses some people's they say well if this is all on the same physical device can I get one VLAN to talk to the other VLAN and the answer is no absolutely not the only way you can get one VLAN to talk to another VLAN is if you actually put a router and connect one port from one VLAN to another port and the other VLAN you actually have to use a router in order to get VLAN to talk to each other again if you're really new with computers and setups you probably don't need VLANs VLANs like I say they get into convergence once you start doing computers and telephones and surveillance systems all on the same network you may come up with VLANs it's kind of a specific thing but it's something that you do need to know about so basically you know you put the computers onto V land one you put the phones on the VLAN two and you put the cameras on the VLAN three depending on what switch you buy you know you can do anywhere from from two to I don't know 50 VLANs you can do lots and lots of VLANs but this is how it works like I said maybe a little confusing but but it really does work in the real world all it does is it separates the ports into different different lands they cannot communicate this port cannot communicate to that port at all whatsoever so the next thing we need to talk about when when you know think about using your switch is something called power over ethernet now I've been talking a little bit today about something called convergence so convergence is where you now use like I say voice over IP telephones you use cameras that connect to the internet or to the network you know all of those types of things things that did not used to be connected to the network are now connected to the network well somebody thought hey wouldn't it be nice if you could actually send power to all these little devices using a switch instead of having to plug the device end so instead of having to run a power cable all the way to a surveillance camera you could you could literally power that surveillance camera simply off the æther net cable or a telephone you could just plug in a telephone and that telephone line would have or the network cable would have enough power coming through it to actually power telephone now you know even going forward actually has enough power to power a full laptop computer so basically what power over ethernet does is not only does the switch send data down down the line but it also sends power so now I think you get was it twelve point nine volts of power there one point nine watts of power going down to the power device the main thing that you have to realize if you're thinking about using power over ethernet because power over ethernet really is great I've used it for like wireless access points when you have to put wireless access points in weird places the Cisco wireless access points with Power over Ethernet it's great you just either plug the access point into a power over ethernet switch or something called a power over ethernet injector and all you have to do is run one cat5 cable to wherever you want that obnoxious little a wireless access point to go and it's powered so it connects in the network and it's powered all at the same time very very very very good two things a warned you about this is again you know as I always argue always buy good quality stuff always buy good quality stuff because the problem is with some of the power over the effort is there is actually a little communication routine that that happens between the switch and between the device that it's trying to power so there are multiple standards of power over ethernet now basically there's version one there's version two and coming along there will be version three so when you plug a device into a switch the switch will ask hey what version are you and then it'll say I'm version Asst and then the switch will send the right amount of power well here's the thing if you're if you buy cheap crap if you buy cheap power over ethernet devices if that little acknowledgment thing isn't done right then your switch could send far more power to the button device than it needs or it could send not enough power to the device so you could really have problems again I would say if you're using power over ethernet just buy good stuff you know by Cisco buy good quality stuff because there is communication between the two things and you get you can fry a device or the device wouldn't work right etc the other thing to realize with power over ethernet just like the back plane of a switch which is the overall amount of communication the switch can do at any one time a switch can only use a maximum wattage at any one time so let's say you have a 48 port switch and it says it could pump out you know 13 watts per port well you have to look at the spec sheet to see how much total wattage it could put out because you know if it can only put out let's say a hundred and thirty Watts that means although you have a 48 ports which you can only connect 10 devices so again you can look this in the spec sheet and you just got to do the little math but like I say if you're buying the Cisco power over ethernet device that is one of the things they'll tell you they'll say how much power it can put out per port and then it can say how much power the entire device can put out because like I say even if all 48 ports are Power over Ethernet you know the total load may not be able to support 48 ports worth of power over ethernet so basically that's all power out there over Ethernet is it is a godsend it is fabulous it is wonderful I've used it it's just just just great because like I say your power and your network connection just runs over that little cat 5 cable again like I say for for wireless access points it's a dream aim for four megapixel surveillance cameras it's wonderful for for phone systems it's great and now like I say the diversion 3 over power over ethernet is actually going to put up enough power to power a laptop so you can just you just plug your laptop straight into a network connection and that's it you're done great so that's power over ethernet now I've been talking a lot about convergence today so convergence is like I say all these new or old technologies are now trying to use a internet or the network so like I say telephone systems used to just use telephone cabling now we have voice over IP telephones that use the network surveillance cameras used to use their own coax cables now they're using the network with all this stuff trying to use the network you come into problems with communications basically if you're trying to download a webpage or if you're trying to download a file it doesn't really matter how fast or slow that file downloads you know as long as you get it at the end of the day it's okay well when you're dealing with voice over IP voice over IP has to be a very fast connection so when I talk my words have to travel down the line as fast as possible to the person that's listening when they talk their words have to travel down the lines as fast as possible for for when I'm listening if there is a bottleneck on the line then everything just don't get stumbled up and go it goes to hell so what the what the the network manufacturers did is they came up with something called QoS or Cisco calls at cos and this is quality of service or class of service so as I talked about before whenever you're sending data from one place to another on the network you send that data in something called packets so so packets are are the lowest type of data it has something called headers on it and it's it's how things get routed well basically what quality of service or class of service does is it prioritizes packets based on what the packet is so basically a voice over IP packet is consider higher priority than a file sharing packet you know a live video stream is a lower priority than a voice over IP packet but again a higher priority than downloading your email at the end of the day the end users that are downloading email or swapping files don't notice the difference but what this does is it make your entire bandwidth doesn't get bogged down again with people sharing files or just doing just stupid stuff on the network by using quality of service or class of service you prioritize your pockets so it is a voice over IP is always the top so it so basically voice over IP will always be able to get through you know live video cameras will be below that so again if there's a lot of lot of people talking and they're using up the bandwidth then then that video stream will be put below all the people using the voice over IP this is very important again depending on what you're doing if you're just if you're connecting you know eight computers together on a little little switch and you might be using Skype quality of service and class of service and who cares it doesn't matter if you're in a company and you're doing 48 computers or 100 computers or 150 computers quality of service really really really does matter again you know if if you have 50 computers to deal with a hundred computers to deal with make sure you buy the Cisco equipment it already has a class of service built in again between managed and unmanaged switches most of the time nowadays the Cisco equipment will automatically detect you know and do all the quality of service settings but you can also go in and you can change your quality of service settings depending on what you need but basically the quality of service or class of service allows you to prioritize packets again if all you're doing is using the internet and sharing files it doesn't matter doesn't matter pointless if you're using voice over IP if you're using digital surveillance you're and you're using computers on the network this is very very very very very important you know quality of service and class of service so the final thing we're going to talk about just spend a minute on is something called the spanning a tree protocol and why it's important so so protocols that you have probably heard of if you're a newbie you've probably heard of TCP IP protocol you know that's the the protocol we use for for Network communications for the internet etc may have heard of banjul which is apples you know little proprietary Network protocol if you've been around for a while you may have heard of IP x SP X and W link net buoy etc these are network protocols that allow you you know different computers to be able to talk to each other one of the things most people don't realize is they're also something called routing protocols so so these these fancy little routers and switches right here they also have protocols that allow them to communicate to each other we'll have another class on this you know routing protocols there's lots of routing protocols out there and it gets really really complicated but basically what you should understand is all these high end switches and routers can talk to each other and they talk to each other using different routing protocols there's something called rip there's something called open shortest path first spanning tree protocol that's what we're talking about now spanning tree protocol is used by switches what this does is it allows the switches to talk to each other and be able to route packets the fastest way possible between multiple switches so like like I said if you have five or six switches all connected together using this trunk using a spanning tree protocol that allows a switches to talk to each other to find the fastest way to send packet from point A to point B the biggest thing the biggest thing the spanning tree protocol does for you though is it also prevents you from having something called router loops or routing loops routing loops if you want to see your geek rip his hair out real quick or real pain in the butt because with low end inexpensive switches like this this of this does not have the brains to have spanning tree protocol in it this is just dumb so here's what happens is if I connect one cable from port one and put the other side of the cable into port two what will happen is when this little guy tries to figure out or tries to tries to talk to all the other computers on the network it will start sending the signal through this and it's called a loop so basically what happens is the communication gets put into a loop and the loops are spending faster and faster and faster and faster and faster and all of a sudden that data instead of going you know out in one port and out one port to the computer it goes into this loop that loop starts burning more and more processing power on this little switch and then after a minute or two you will actually shut down your network I have seen this time and again this isn't a joke this isn't melodrama if you want to see the eye sight you will see something really funny if you have a little keep switch that's running your network just connect cable from from from port one and just take it to port two and why the network shut down now you know you may be thinking hey who's stupid enough to do port one to port 2 ha of course nobody's going to do that but what people will do what they will do and again I've seen this in the real world is let's say you have a network or Jack in your office or you have two network ports in your office people don't know what they're doing and they say hey I need to connect an extra computer in my office so they take a cable from one network jack and plug it into the switch and then they plug their two computers off and so now they're two computers are on the network what I've seen happen is then somebody who doesn't know what's going on plug the cable into the other port and the wall and then plug that into the new switch so now you have the the first port from the wall plugged into the switch and now some plug the second port into the wall into the switch and now you have a bigger routing loop so basically you have you have a big switch you know in the back and the MDF one cable comes it goes into here and that goes back out and comes back and then like I say this is this loop starts working and then after a minute or two the entire will will shut down really really does happen so that's why you know if you're if you're dealing with a business class and enterprise network again with 50 or more users get again I would say a Cisco switch it uses something like I said called open shortest path or spanning tree protocol and the biggest thing with spanning tree protocol it does spanning tree protocol there's a lot of other cool stuff but the main thing it does is it prevents loops if it sees a loop it shuts that loop down because believe me like I say once you get 50 or hundred people all doing stupid stuff in an office they can just do the most moronic crap and and this happens I literally had this happen with one of the networks that I was cleaning up for a client their network was actually so bad that they didn't realize that they had a loop in the network but all the equipment was so bad and the network was so slow the loop never actually caused the entire network to crash so all I did is I came in I put new Cisco equipment in I put on all the nice new networking stuff I connected stuff exactly how it was and again within two minutes it shut down the entire what 30 person network the reason was is because once I put in this new high quality equipment well everything sped up really fast and then like I say it took it into a loop so that's what spanning tree protocol does really for you is it prevents these router loops I say they're they're just horrible so that was a class on understanding switches switches are pretty simple things but like I say for some reason most too many technicians don't don't really understand a lot about them but I mean they're very powerful little devices and again I mean they're they're the center of your network without a switch you don't have anything so we talked about in the beginning we're hubs and hubs basically like I say they just split the signal they split the network signal just like a little cable TV splitter does the problem was is if any two computers try to talk at the same time there's a collision on the network each computer would wait a random amount of time to try to talk again again this was okay for four or five computers didn't matter once you put 20 once you start putting 20 30 100 computers on the network well they're all basically trying to talk at the same time there's all these collisions everything just turns into a mess this was generally called a broadcast storm when all the computers are trying to talk at the exact same time and nobody can talk and it's a mess so basically what they did is they came out with switches switches like I say the when computer one tries to talk to computer for the the packets will be sent up to the port on the switch the switch will then go oh I see computer one is connected to port one the packets are then sent out on every single port on the switch when when computer four responds the switch then knows that computer four is connected to port four so when computer three tries to connect tries to talk to computer four instead of all the packets going out on every single port it will only go out on port 4 this allows so computer one can come talk to computer four at the same time computer three is can talking and computer to computer 10 is talking to computer 11 by by having this routing inside the switch now multiple computers can be all be talking at the exact same time we talked about the speeds you know 10 megabit per second hundred megabit per second gigabit per second that's all pretty simple again we taught about half-duplex and full-duplex again I don't know what uses half-duplex anymore but we got to tell you about it half duplex is you can only talk or listen at any one time full duplex means you can talk and listen at the same time remember with all this stuff in the switch this is all done automatically so when you have a networking device whether it's a computer or a printer that connects to the port that's connected to the switch the switch and the computer will talk to each other to find out how fast the computer can talk to the switch this is all automatic with all automatic things you know things can get messed up that's the nice part if you have what's called a managed switch that we talked about you can actually go in and a hard-code the ports to what you need them to be you can hard code all the ports to 100 megabits per second or to a gigabit per second etcetera we talked a little bit about the backplane that plane is a very important thing like I say when you're dealing with enterprise clients when you're dealing with five people nobody cares with enterprise clients remember all these ports may be a hundred megabits per second but the backplane is how much overall communication can happen at any one time so let's say you have only 48 ports which yeah 48 100 megabit per second ports but the backplane this is only this is an exaggeration but let's say the backplane was only a gigabit per second you know it was only capable of doing a gigabit per second communication that means you can only have 10 computers talking at any one time at 100 megabits per second can cause a real problem after that we talked about trunks like I say the trunk connectors you have the normal 48 ports on these Enterprise switches and then like with Cisco and I'm not sure about the other brands they're called G Beck or trunk connectors these trunk mount connectors allow switches to connect to other switches so it's called daisy chaining so if you have five or six switches you connect them using the trunk connector not using the normal ports again with enterprise switches those trunk connectors are normally a fiber optic connections and so they can handle much more data than a normal port can so you know if this is a 100 megabit per second connection that trunk can handle 10 gigabits per second very very nice and like I say with the higher end ones you'll normally get fiber optic connectors but even with lower ones a lot of times they'll have that trunk connector and even if it's still just a 5 they still got it and so that's what you should use to connect your switches together I thought about VLANs VLANs are virtual lands again until you get into more complicated networking you probably not deal with this but but why it's important does it means you can you can set up different ports on your switch to to be in different lands so basically like I say if we you know I had that picture you could set up three different VLANs on that switch and the VLANs could not talk to each other at all it is impossible you actually have to put a router in between the VLAN for them to talk so again if you have a you know if you have your computers and you have your telephone systems and your surveillance systems you don't necessarily want them to talk even though that they're running through the exact same switch that's what VLANs allow you to do we thought about power over ethernet oh I say power over ethernet is an absolute godsend so not only can you send data through a cat5 cable but you can actually send power you know more than enough power to run wireless access points more than half power to run voice over IP telephones and to run surveillance cameras the new power over ethernet standard that's coming out soon will actually be able to run laptops so you can just sit down at a network cable and plug your laptop in and it's all good to go again there are multiple standards of power over an Ethernet why I always argue make sure you get high quality parts is because there is low communication routine when you plug in your power over ethernet device it will talk to that power over ethernet switch if they don't get that communication proper you could have real problems and this is power this is electricity so when you have problems with electricity things get go boom they may not go boom like it explodes but little capacitors and resistors and all that kind of stuff fry and then your your thousand dollar megapixel camera it is now toast again you know we talked a lot about and it's a big thing the whole convergence idea you know now telephones are using network cable surveillance systems are using a network cable identification systems are using network cable along with computers etc so what they came up with was quality of service or class of service QoS or cos like I say almost everybody as a QoS quality of service cisco calls it cos class of service just because what this does is this prioritizes packets so it means that the voice over IP packet has a higher priority than again streaming video packet which has a higher priority than sharing files packet this is very very very very important again if you don't really do voice over IP or any of that then it doesn't matter if you're in an enterprise environment and you know you're using 48 port switches this is a big deal because if the packets cannot be prioritized then you can have if you're sharing the people sharing files can start using up all the bandwidth and then your people trying to just make a normal telephone call don't get any of the bandwidth and it just causes a complete mess and then finally we talked about spanning tree protocol again this goes into routing protocols we'll have another class on routing protocols because that gets all complicated routing protocols actually are the routers or switches and how they communicate with each other they don't send email back and forth but they do they do talk one of those protocols is called spanning tree protocol the main thing that you should think about with spanning tree protocol is that it prevents what are called router loops it prevents loops from happening on your network again if you get a loop and you have a little keep unmanaged switch when you get that loop your entire network will shut down I've seen this again and again and again and again and again and again and again this is not a one-time thing this is not an if this is not a maybe if somehow one port gets connected to another port it shuts the entire network down and again like I say is you could have the main switch you know way back in your MDF and you know you could just have I don't know the sales guy that thinks he's being smart and he plugs us a switch in in his office and believe me when you've got that like I say if you've got 100 or 200 users and somebody does something dumb like that I mean that that is difficult to troubleshoot that's that's just horribly difficult to troubleshoot you got 200 computers so so what I would say is like I say Cisco Cisco is always good all their stuff has a span spanning tree protocol and and it will just it'll just be an absolute lifesaver now as you know notice I've been showing you Linksys stuff you know like small Linksys and managed Linksys I do yes I do use primarily Cisco equipment my Cisco switch is downstairs screwed into the rack so I'm not bringing it all the way up here and my Cisco wireless access point again is screwed in Cisco is good cisco cisco cisco cisco cisco equipment is just it just really is wonderful you know i know when you have clients or if you're thinking about buying equipment you know you're going to see the price difference you know as i talked about before you know the Cisco wireless access point costs $600 my cost versus a lynx this wireless access point that cost 80 but the difference is is is just amazing when you start dealing with networking once you start installing networks once you started maintaining networks remember that this is the wiring for your network if there is one flip and the thing on your entire network that should be stable it it's the core of the network it is the switches it is the routers I mean you cannot have a network without a switch if you don't have a switch you don't have a network and it's it's utterly that simple so when you're dealing with clients and when you're dealing with yourself cisco stuff is not that expensive now I mean it's more expensive than Linksys of course but but like I said you had you have to look at what would the downtime cost if if you started having problems on the network what is the overall cost you know 48 port Cisco 10 100 megabit per second switch I mean cost you like $1,500 now shipped to you that is wonderful you can get a $3,000 for 48 port gig Cisco switch I mean that's amazing so what I would say is whether you like Cisco whether you like Juniper Networks a HP I've never played with their stuff but I guess they're good just buy high quality networking equipment the switches I'm telling you it would just save you so much money and in frustration in the long run so well as you know I'm Eli the computer guy this was understanding switches so I hope you understand switch is a little better now as always it was good to see you at the class and I look forward to seeing it the next one

Channel: Eli the Computer Guy

Views: 1,351,395

Rating: 4.9085197 out of 5

Keywords: understanding, switches, 720pH

Id: 9yYqNqTNnqI

Length: 58min 9sec (3489 seconds)

Published: Thu Feb 17 2011