CCNA 2 Chapter 4: Switched Networks

it's about the end of spring break and what better way to end spring break than with another CCNA to video this time it's chapter 4 a great chapter to end spring break with why because it's nice and short so this should go pretty quickly it's also pretty much a review chapter so there won't be too many new concepts we've got the concept of a collision domain and broadcast to may domain switch ports security those will I think be the only new concepts that you'll see vs. CCNA 1 because in C you see anyone we Tasha but talked about switch networks quite a bit so we're going to start off with local area network design and this plot this slide is just talking about the complexity growing complexity of networks whereas you don't have a single office or a single building that your network is isolated to you don't end your employees don't need to be on site to access your network your information must be able almost have the capability of being accessed anywhere in the world in most situations so that is going to make things a bit more complicated when setting up a network we also have the idea of a converged network where you have all different types of data being sent along the same network you need to keep those conversations separate you need to keep them in order we talked about how that works in CCNA 1 through different protocols that are in place so again this is somewhat review in fact it is review we've seen the idea of a converged network I believe in one the first two or three chapters in CCNA 1 so nothing really new here multiple types of traffic different types of data that could be sent voice email videoconferencing basically anything over the same network so you can go ahead and read those different bullet points there but we've discussed them before here we have the idea of a borderless networks just basically meaning that your network can again as we refer to before V access from anywhere so you've got different portals to get into each network here if you wanted to okay so anything can be accessed from anywhere your network needs to be easily needs to be easily scalable reliable and you have policies in place to make that happen you have access control lists that can be set for each different network or the entire network as a whole depending on how you want to set it up ok so this is just an idea that the access the network can be accessed anytime from anywhere if you have the proper credentials or the network has been set up so that you can access it of course you can set up your network so that certain individuals or certain devices can access it and certain devices can't and we'll be getting into those types of settings in the next few chapters here again we have some review in the hierarchy and a borderless switch network we've seen the core distribution and access layers in CCNA 1 got the principles that's built off of that it's hierarchical that if each layer performs a specific function you've got your end users and switches down here servers at the access layer you've got your routers that may be less powerful here and then you've got routers up here that are usually the more powerful devices that send your traffic to different regions ok that is not as typical a set up you basically take these two and combine them and you get a collapse core where you just have your end users and then you just have your routers slash high-speed routers here and you're communicating through a collapse core system rather than having two separate sets of routers here ok that's more typically what you would see and these these are symbols actually are not routers these are layer 3 switches which you'll see a little later on the materials but they could be routers or layer 3 switches layer 3 switches do perform routing functions ok you got modularity basically allowing you to add to your network setup as you need to that's what modularity means basically the ability to add or subtract as need be resiliency is your network always on flexibility can you share resources or use resources in the most efficient way possible to meet and user demands so those are things that go into your borderless switched network and again we've discussed this a little bit in CCNA one and here you just have an example of your access distribution which would be again your lower powered routers in your core which would be your higher powered routers in the middle here and typically you're going to kind of combine those two so that would be your collapsed core distribution model there okay what we're going to concentrate on is the role of switched networks here one second we'll go back to the previous slide just make sure you get the access layer and define these access layer which is your switches that will be at the edge of your network typically connecting to another switch or combination of switches and routers at the distribution layer at that that's typically where your quality of service your security your routing going on and then that's going to connect to your backbone of your network with your highest higher powered devices you're faster routers faster switches if need be it could be a layer 3 switch as well ok and a collapsed core would just be taking the distribution and core responsibilities and kind of just combining them into a single device which is more of a typical setup these days so we'll jump back here again so the role of our switch network we talked about switches and what they do they basically make sure that traffic is sent only to the destination device rather than flooding the network with a bunch of traffic which would be more like what would happen if you had hubs in a network which are devices that we shouldn't really see in networks too much anymore okay you in the past would have more of a flat switch network system you might still see that that's not too uncommon but you can also have a hierarchical switch network like this where you might have a couple regular switches and a couple layer 3 switches finally connecting to a router up here so the setups can be complex or or a little more simple the switch Network does allow you to have more flexibility more traffic management quality of service additional security can be implemented on each of these devices and of course it supports wireless connectivity mobile services IP telephony so you all see all of that down here ok so we'll be setting up a couple of these types of services to ensure security make sure traffic only goes where it wants things of that nature really light in this chapter to begin with then we get more into VLANs and interview and routing a little bit we talked about fixed switch configurations and the different types of switches that are available in C to name one so fix just normal switch modular platform you can go ahead and add more ports through adding blades to this modular setup a bit more expensive but does allow you a bit more flexibility you've got stackable switches which well can act as one switch essentially it's different from having just force which is connected normally in that if you were to receive a frame into one port of any one of these switches in the exit port was in this set it would only have to do one lookup to send out that exit port okay in the in the MAC address or kam table all right but if these were not stacked like this let's say that I don't know you've got to switch up here number one and these are all connected and it needs to end up going out a port and switch for ok and all these switches are in between one and four switch one would have to make decisions say okay I need to go to let's say fast ethernet port 4 on switch 2 and switch two needs to look up and say ok I need to go to fast ethernet 6 on switch 3 and there's basically one two three four times you have to look in your MAC address or cam table to make a decision as to where that frame is supposed to go with a stack configuration you only need to do one lookup okay so it's okay it needs to go out switch fours port blah blah blah and just sends it on down okay so that's the advantage of stackable configuration switches versus just having four that are corrected or connected normally so here we go switch environment so again a little bit of review we've got how switches make decisions in frame forwarding they as we've talked about before learn about MAC addresses to store in this MAC address table through the ingress or source address on a frame okay so ingress port means the port on which data is flowing into the frames going into that port that's ingress as that switch sends the data out that's the egress port okay so ingress for data coming into the switch egress for data going out of the switch okay so it makes a decision based on the ingress poor because that's how it learns addresses and the destination port it's going to look in its MAC address table to see if it has a a match for the destination port and send the traffic out there of course if there's no match then the switch is going to broadcast that frame out and eventually hopefully well it should learn about the destination port as it sends traffic back to the original sender and basically here we have what we just talked about the process the switch uses to learn about these MAC addresses so as frames come into the switch it learns MAC addresses it's stored in the cam or MAC address table cam is a content addressable memory which is used in high speed searching that applications information in the MAC address table used to send the frames talk about that if it's not in a MAC address table it will flood to all ports or broadcast out all ports more review we've talked about store and forward versus cut-through store and forward is the default configuration for your switch it'll go ahead and use Sora store and forward which will do a error check and make sure the frame is intact before sending it on out cut-through is just going to make sure that it reads the destination address and then send it on forward depending on what type of cut-through method you use you got both fast forward fast forward and fragment free cut through methods so I think we'll see in the next couple slides okay so going forward is first which basically takes a look at the entire frame does a frame check sequence um a cyclical redundancy check make sure the frame is intact and then fords it on out so you don't have well errant frames running through your network is a little bit slower but not much or noticeably most the time you'll just go ahead and leave on storm forward switching but if you want the fastest wishing possible you'll be using cut through cut through forward of cut through switching basically takes a look at the destination or reads just enough to see what the destination MAC address is then sends it on out okay that is fast forward cut through switching there's also fragment free which will read the first 64 bytes to make sure it's not a runt frame and then it'll send it on out that way so those are the two different techniques I don't think you need to know the two separate ones for this chapter we did discuss them Ekans you cna one tho here we have the concept of collision domains you want to make sure you know collision domain versus broadcast domain each port on a switch is its own collision domain a collision domain is a segment where devices compete to communicate so each port on a switch you could at pop have possible collisions if you were in half duplex mode because you have devices competing to send and receive on that same line or on that same port okay so that's what collisions could exist if you're in full duplex which is the default and you shouldn't see many half duplex situations these days you're not going to have this collisions at all but it is important to know that that collision domain is each port on a switch being its own collision domain or segments where devices compete to communicate okay if you have a device like a switch that's set up for do full duplex and a PC for instance maybe it's set up with half duplex for some reason the switch will notice that full duplex is not working and switched to half duplex okay that is that's going to happen when the initial communication starts between the PC and the switch okay in fact if there's any error in communication using full duplex the switch will go ahead and knock itself to half duplex so even though a device might be full duplex on the other line if there's a few errors in the initial communication process the switch can revert to half duplex and you might have to go in and switch it back to full manually so that's something that can happen just be aware of that a broadcast domain is different broadcast going domain as well where traffic will be broadcast to each switch I shouldn't say each switches its own broadcast domain because if you have multiple switches connected together they are all considered part of the same single broad Cass domain okay it's basically where your broadcast can be heard all right so if you don't have network separation or separate VLANs set up you're all in the same broadcast domain so we're going to talk about reducing the size of your broadcast domain to optimize your network speed on your network traffic in the next chapter all right so that's what a broadcast domain is again that's where well whatever your broadcast can be heard and for our knowledge at this point that would be a network basically in each network is its own broadcast domain when we break VLANs down each VLAN will be its own broadcast domain okay but we don't do that just yet we haven't done that just yet and we have a couple ways which is help alleviate networks and congestion like I said each port on a switch is at its own collision domain so it's basically splits up different you're different collision domains into separate separate ports so that's going to help your network out rather than all being run into the same port providing full duplex communication taking advantage of their high port density or high port number buffering large frames employing hype sea ports taking advantage of their fast internal switching process having a low per port cost well in general depends on what's have to switch you're buying they can't get a little expensive and that's the end of the chapter so not too much content here no commands just concepts if you need to read a little bit more about this or that maybe your access distribution core layers I think a couple of those questions will come up your collision and broadcast domains it is a pretty light chapter though the test hopefully won't be that hard and we'll get into more commands in regards to switches switch ports security and things of that nature in Chapter five

Channel: CeeJayII

Views: 15,182

Keywords: CCNA 2, CCNA, Switched Networks, CCENT, Cisco, academy

Id: S2YHeL-yFps

Length: 17min 39sec (1059 seconds)

Published: Sun Apr 23 2017