Free Network+ Training - Module 11 - Switch Basics (N10-009)

Summary

In Module 11 of the Free Network+ Training by Dark Bird Tech, the focus is on the basics of network switches, crucial devices in modern LANs. The video takes a step back to explore pre-switch technologies like hubs and bridges, highlighting their limitations and the introduction of switch technology to enhance LAN performance. The concept of Collision Domains and the importance of Media Access Control (MAC) Addresses in networking are discussed, along with different types of switches, including managed, unmanaged, desktop, enterprise, fixed, chassis, and stackable switches. These segments make up a comprehensive guide to understanding switches' role in network infrastructure.

Highlights

• Switches replaced older devices such as hubs and bridges, offering improved efficiency in LAN environments. 🔄
• Hubs create one big collision domain; switches create many small ones, enhancing traffic management. 📈
• MAC addresses are integral for data transmission in LANs, ensuring data reaches the correct destination. 📫
• Different switch types cater to diverse operational needs, from small offices to large enterprise networks. 🏢
• Managed switches provide configurable options that are highly beneficial in enterprise environments. ⚙️

Key Takeaways

• Switches are essential devices in modern networking, significantly improving LAN performance over older technologies like hubs and bridges. 🛠️
• Collision domains define network areas susceptible to collisions, with switches offering more refined control compared to hubs. 💥
• MAC addresses are crucial for network communication, being unique identifiers that help direct traffic accurately. 🔄
• Managed switches allow for configuration and settings adjustment, whereas unmanaged switches offer more straightforward plug-and-play use. 🔧
• Switch types vary, including desktop, enterprise, fixed, chassis, and stackable, each serving different networking needs. 🖥️

Overview

The module delves into understanding how network switches have revolutionized LAN setups. Originally, networks relied on hubs, which are simple devices that repeat signals to all interfaces, leading to inefficient data flow and potential network traffic congestion. To overcome these issues, network engineers introduced switches, which are smarter, layer 2 devices that use MAC addresses to direct traffic efficiently.

Unlike hubs, which create one extensive collision domain, switches break down networks into smaller, manageable collision domains, reducing the chances of traffic collision and improving overall network performance. Switches continue to build on the basic functionality of bridges, adding multiple interfaces and improved traffic handling capabilities. Modern switches can be managed or unmanaged, providing flexibility and control to fit specific needs.

Advanced features like managed switches enable network administrators to configure VLANs and Spanning Tree Protocols, which are critical in complex network environments. The module also explains different switch configurations such as chassis switches, offering modular flexibility, and stackable switches, which allow for network expansion without the need for costly upgrades. Overall, the module provides a comprehensive introduction to the critical role switches play in modern network infrastructure.

Chapters

• 00:00 - 00:30: Introduction to Switch Basics This chapter introduces the basics of network switches, highlighting their prevalence in modern LANs. It begins by discussing pre-switch technologies, specifically hubs, and explains how they were represented symbolically as a square with an arrow. The chapter sets the stage for understanding the significance of switches by exploring their historical context and evolution from earlier networking devices.
• 00:30 - 01:30: Understanding Hubs and Their Limitations Hubs are often referred to as multi-port repeaters. Despite icons or templates showing two arrows, they consistently point in the same direction. These devices, characterized by multiple interfaces, function by repeating the signals they receive. Hubs operate purely at OSI layer 1, emphasizing their role as physical devices. The essence of their operation is captured succinctly in a single sentence.
• 02:00 - 05:00: Introduction to Bridges The chapter introduces the concept of bridges, explaining their function in network communication. It discusses how bridges receive, amplify, and transmit signals to connected devices, using an example where a signal from a source computer is sent through a hub to a destination computer, and how the signal is also sent to other devices connected to the hub. The chapter illustrates the fundamental behavior of network devices in handling data transmission and the concept of signal repetition to all interfaces.
• 06:30 - 15:00: Carrier Sense Multiple Access with Collision Detection (CSMA/CD) The chapter delves into the fundamentals of Carrier Sense Multiple Access with Collision Detection (CSMA/CD), explaining how it operates as a network protocol. It addresses the mechanism by which devices connected in a network using CSMA/CD detect collisions, specifically in Ethernet networks.
• 15:00 - 23:00: Collision Domains and Switches The chapter discusses the concept of collision domains in network topology and how they are managed using networking devices such as hubs and bridges. It explains how a hub functions by amplifying and repeating signals to all connected devices, causing unnecessary processing by computers that receive unintended data. To improve efficiency and introduce intelligence, bridges are used. They help manage collision domains by ensuring that data is only sent to the intended recipient, thus optimizing network performance. The chapter notes the visual representation of a bridge seen in network diagrams, which resembles a suspension bridge.
• 23:00 - 30:00: Understanding MAC Addresses This chapter focuses on understanding MAC addresses, particularly in the context of Layer 2 devices like switches in Local Area Networks (LANs). It explains how these devices work with MAC addresses by learning them from the frames they process, and associating them with the interface on which they receive the frames. This association is essential for the efficient routing of data packets within a network.
• 31:30 - 37:00: Switch Operations and MAC Address Tables The chapter discusses the operation of switches and how they utilize MAC address tables. When a device is connected to a bridge and sends traffic, the bridge records the source MAC address from the frame. By interacting with and learning from this information, bridges associate MAC addresses with interfaces, enabling effective network segmentation and traffic management within a network, especially when placed between network devices such as hubs.
• 37:00 - 47:00: Address Resolution Protocol (ARP) and Switch Communication The chapter discusses the Address Resolution Protocol (ARP) and switch communication, emphasizing the importance of MAC addresses. The instructor uses simplified examples of MAC addresses (such as 01-02-03-04-05, AA-BB-CC-DD) to facilitate learning. The chapter advises on the possible complexity of MAC addresses encountered in the Network+ exam and underscores the necessity of careful reading. The overall goal is to simplify understanding while acknowledging that real-world scenarios may present more complex MAC address formats.
• 47:00 - 52:00: Types of Switches: Managed vs. Unmanaged This chapter discusses the types of network switches, specifically managed versus unmanaged switches. The focus is on how bridges learn MAC addresses. When a bridge sees new traffic, it associates the source MAC address with its interface, essentially "learning" which MAC addresses are on which interfaces. The explanation simplifies some steps for clarity.
• 52:00 - 55:00: Desktop vs. Enterprise Switches The chapter discusses the differences between desktop and enterprise network switches. Initially, the transcript mentions the handling of MAC addresses in network traffic. It illustrates a scenario with computers communicating over a network hub. Unlike hubs, network switches, particularly enterprise ones, keep track of source and destination MAC addresses to efficiently route traffic. This enhances the data transmission process compared to a hub, where data is sent out indiscriminately in all directions.
• 55:00 - 59:00: Fixed vs. Chassis Switches The chapter discusses the behavior of network devices like hubs and bridges in handling Ethernet frames based on Mac addresses. Hubs indiscriminately send frames out all interfaces, whereas bridges analyze the source and destination Mac addresses to make more efficient routing decisions, employing a process known as filtering when both addresses are on the same interface. This highlights the fundamental differences in the operation of these devices, particularly focusing on the efficiency improvements offered by bridging technologies over basic hub functions.
• 59:00 - 61:00: Stackable Switches This chapter discusses the decision-making process of stackable switches in a network setting. It highlights how a bridge optimizes data traffic by not forwarding unnecessary traffic to the other side. The focus is on understanding the efficiency of data handling where the bridge only forwards traffic if the destination is on the other side, avoiding redundancy. The text also briefly mentions how traffic interacts with a hub at the layer one level of the OSI model, with source MAC and destination MAC addresses involved in the process.
• 61:00 - 60:00: Conclusion and Upcoming Topics The chapter 'Conclusion and Upcoming Topics' explains how network bridges and hubs operate in a network by looking at source and destination MAC addresses. It briefly mentions an improvement in technology with switches which handle data transmission more efficiently compared to hubs. The chapter concludes with a hint towards upcoming topics that will cover how switches operate and improve network performance.

Free Network+ Training - Module 11 - Switch Basics (N10-009) Transcription

• 00:00 - 00:30 hello there let's do some switch Basics because switchers are so widely used nowadays you find them in pretty much every landan you'll come across but before we can appreciate why switches are so special we need to talk about some of the things that came before them so let's do some pre- switch Technologies and the main Lan device that predate switches in a way that you would recognize a landan as a landan would be hubs now the symbol for a hub is usually a square with one arrow in
• 00:30 - 01:00 One Direction although I have seen some icons and templates that use two arrows but they'll always be pointing in the same direction now a hub is what we call a multi-port repeater it has multiple interfaces and is designed to repeat the signals it receives so it basically works at OSI layer 1 it's a purely physical device and its method of operation can be remembered in one single sentence
• 01:00 - 01:30 it receives a signal it amplifies that signal and then it sends that signal or repeats it out of all of its interfaces so if I were to connect a couple computers to this Hub and let's say the one on the left is the source of the traffic and the one in the middle is the destination the traffic would make its way from The Source computer to the hub and then out that interface to the destination but it repeats it out of all interfaces so it's going to go to that third computer who's just sitting there mining its own business and now it's
• 01:30 - 02:00 receiving traffic that is going to have to process and work out oh that's not meant for me now that doesn't sound too bad in a small Network like this but let's scale that up let's say we've got multiple hubs and multiple computers connected together and let's say the source and the destination are both on the left Hub there the source computer sends us traffic and obviously it goes out the other interface to the destination but remember it's going to go out of all interfaces so it's going
• 02:00 - 02:30 to go to that Hub on the right there and now that Hub is going to do what the first one did take that signal amplify it and send it or repeat it out of all interfaces so those two computers over there get stuff that they are not meant to get they're going to have to process this until they work out this is not meant for them so to try and introduce some usefulness and intelligence into our Network we introduced Bridges now the icon for a bridge is this thing sort of looks like a suspension Bridge
• 02:30 - 03:00 without the two parts on the side going down to the ground on each side of the canyon I have a very visual mind I'm sorry and it was our very first major layer 2 device for lands now being layer 2 it is able to work with Mac addresses and it will learn the Mac addresses from the frames that it is processing and as it learns those Mac addresses it Associates them with the interface that it received the frame on so that means that when a computer is
• 03:00 - 03:30 connected to a bridge in any way when traffic it sends reaches that bridge that bridge is going to pay attention to the source Mac address of the frame or the layer 2 traffic and that bridge will now remember that Mac address of 01 02 0304 05 AA and Associates it with that interface so if we take that Network we were looking at just now and take that cable out from between those two hubs and stick the bridge in the middle what we're going to land up with is a network
• 03:30 - 04:00 where a little bit of intelligence will be present so obviously we're going to care about these guys having mac addresses as you can see I've made some easy to read Mac addresses 0 1 0203 04 05 a a BB CC DD literally it's the last two digits that differ Please be aware that when you're tackling the network plus exam they might not be as nice with what the Mac addresses look like so just read them carefully but for learning purposes I think we can get away with Mak making the stuff a little bit easier to read
• 04:00 - 04:30 and to talk about now as before we have the same two PCS acting a source and destination now the bridge is going to learn the Mac addresses we've skipped ahead and the bridge now magically knows it already what will actually happen though is when the bridge sees new traffic arrive it'll look at the source Mac address field of the frame and if it's new to this bridge it will associate it with that interface so it now knows that Mac address blah blah blah AA and BB is on
• 04:30 - 05:00 the left interface and Mac address blah blah blah CC and DD are on the right side now we can have the source computer sending some traffic out the Hub that that traffic arrives on still does what a hub does out of all interfaces but this time we're actually going to be keeping track of source and destination Mac address so out it goes but this time it gets to the destination fantastic
• 05:00 - 05:30 the recipient receives it sees their Mac address in the destination Mac field and Carries On processing it but the Hub still sends that one frame out the interface that actually didn't need to but the Hub doesn't know any better so we can't blame it the bridge will have a look at the source and destination Mac address and go hm I see that the MAC address for the source and the destination is on the same interface there is no need for me to send it out the other side so the bridge does what's called a filtering
• 05:30 - 06:00 decision and chooses not to forward that traffic so in this situation it's nice the bridge has not sent the traffic to the other side unnecessarily however what if the destination is on the other side of the bridge well in that case what's going to happen now that traffic hits the Hub source mck is AA destination Meers CC and the Hub doesn't care because it's layer one out of all inter faes the
• 06:00 - 06:30 bridge looks at the source and destination Mac address and realizes yes the source Mac is on the incoming interface but the destination Mac address is on the other side I better send it out the other side so now it arrives on another Hub now that it's on another Hub that Hub is going to do what it does best out of all interfaces so it does get to the destination but it still went to everybody didn't need to go to thankfully though when we do look at how switches work they do this just better but there's another interesting
• 06:30 - 07:00 technology that you need to know about comp is definitely going to want you to know about something called csma/cd and the reason is we still use it in our lands even though we've got switches now you'll see why I said that the way I said it so first of all what's This Acronym for Carrier sense multiple access with Collision detection that's what the slash is for so this is a ethernet service designed back in the era of hubs and
• 07:00 - 07:30 even before hubs when we used to use something called a bus topology so this is what a bus topology would look like a bunch of computers all connected to the same cable this was actually very common when we used to use Co actual cables for our networking now why is this necessary well in a network where everybody shares the same single cable we have some potential dangers so csma/cd outlines normal Communications
• 07:30 - 08:00 and it's normal conditions and rules for all of these computers here is listen before you send traffic onto the network when you listen to the network one of two things will happen either the network is quiet no one's using it you can send traffic or you listen to the network and you hear it's busy right now you hear someone's using it you wait till it gets quiet then you can have your turn now that sounds great but there's a problem with it what if two Compu computers listen to the network at the
• 08:00 - 08:30 same time and come to the conclusion at the same time that it's quiet and they both send at the same time this traffic starts making its way down the cable the electrical signals start going to the computers connected but at some point these two signals are going to run into each other and we have now what we call a traffic collision now nothing dangerous is going to happens so don't worry but the electrical signals that make up the traffic are going to start running into each other and messing with each other
• 08:30 - 09:00 over amplifying or negating each other going to be unpleasant now what is csma/cd going to do for us well it says carrier sense multiple access with Collision detection so we're going to detect the collision and recover from it so when the Collision occurs the first PC that sees or technically hears the Collision will send out something called a jam signal so let's say for instance that computer was computer B with a Blue Dot above it
• 09:00 - 09:30 right now it sends out a jam signal throughout the network and everyone sees that jam signal now what makes the jam signal special is it lasts for three times the duration that a normal Network transmission would last so this Jam signal will definitely outlive the Collision so the Collision obviously dissipates because the signals eventually stop being sent but the jam signal carries Ong goinging so we know that all the other computers in the network have heard this Jam signal
• 09:30 - 10:00 now all the PCS will have to set for themselves a random timer so they're all going to have a little clock and they're all going to set for themselves some random times they probably will not be nice multiples of 10 I just do this for the ease of reading and speaking but in reality it'll all be random numbers some will say 10 milliseconds some will say 13 some will be two it'll be random it'll be all over the show when the jam signal ends the random timers begin counting down to
• 10:00 - 10:30 zero so the jam signal now goes away and these timers can start working their way down but what happens when they reach zero well you cannot send any traffic until your timer reaches zero however you can still receive it obviously when your timer reaches zero you can have your turn so judging by it we've got PC a with 10 milliseconds B with 20 C with 40 and D with 70 so 10 milliseconds will pass and a gets down to 0 milliseconds
• 10:30 - 11:00 and a can now transmit that traffic now remember all the other devices are still counting down but they can still receive while they're counting down they just can't send anything so they can't reply but that's fine a got his traffic out lovely stuff now the timer is carry on running down and another 10 milliseconds pass and B hit zero but B's got nothing to say so it makes no difference to B another few milliseconds pass and C hit zero as well C didn't have anything to say so it makes no difference then
• 11:00 - 11:30 another 30 milliseconds pass and D hit zero and can send its traffic out and now we have successfully recovered from that collision and the two devices that caused it were able to retransmit that data and that's fantastic and this used to work very well years and years ago when our lands were pretty simple and small but obviously you and I both know our lands are no longer simple and they're no longer small so we needed something better don't worry you'll see
• 11:30 - 12:00 why so first of all Collision domains we want to be able to recognize and identify Collision domains in our Network any area in your network where a collision could occur and you need csma/cd to bail you out is a collision domain now hubs create one big massive collision domain and switches create many small Collision domains generally one paraphysical interface so if we plot a all Network out here where we're going to have a
• 12:00 - 12:30 router just to break everything up and on the left side we're going to have a hub and two PCS and on the right side we're going to have a switch and two PCS jumping the gun a bit but that's the switch now this is where the Collision domains will be hubs create one massive collision domain switches create one per interface and the thing about the switches one is it's actually beneficial to us the reason being in the hubs collision domain here if a collision occurs on this cable
• 12:30 - 13:00 over here this computer and that interface of the rout have to take part in csma/cd despite the fact that they were nowhere near the Collision so they have to suffer even though it was a collision on another interface whereas over here with the switch if a collision occurred there between the switch and the PC that PC and that switch's interface over there have to do csms CD this interface and connection to the router can carry on as per normal
• 13:00 - 13:30 this interface and that computer can carry on as per normal this is one of the benefits of a switch having many smaller Collision domains makes sense if this was for example different cities or Villages towns whatever having an accident in one town affects other towns that doesn't make sense if there's a traffic accident if there's a traffic accident in that town why should people in the neighboring towns suffer doesn't make sense to me so this is a better option this is
• 13:30 - 14:00 nicer now before we get into the switches properly we want to look at Mac addresses as well we have looked at Mac addresses a couple times already but let's just make sure we're all clear on exactly what Mac addresses are and they are a form of physical addressing Mac addresses or media Access Control addresses are a popular OSI layer 2 addressing mechanism they are made up of 48 binary bits and thankfully we don't have to memorize those 48 1es and zeros
• 14:00 - 14:30 because we'd rather write them using 12 heximal characters and they are built into your network card they are literally etched into the chips of the network card controller circuit so they are part of the network card the only way you're going to get a real new one is by getting a new network card now you might have come across this thing called Mac address boofing and if you're working with Windows 10 or 11 you might have seen that when you connect your computer to a guest Wireless Windows offers you
• 14:30 - 15:00 the ability to randomize your Mac address for Security that is called Mac address spoofing and it is a way to tell your computer to lie about it Mac address just before the traffic leaves the network card piece of software running on the computer intercepts that and removes the real source Mac address from the frame and puts a fake one in there tricking the network into thinking oh that's actually what your Mac address is now it doesn't actually change what your Mac address is it just changes what the rest of the network thinks it is
• 15:00 - 15:30 it's sort of like if somebody gives you a fake phone number instead of their real phone number you won't know it's fake until you try and call them guys if you don't know what what this is about ask the ladies they'll tell you sorry ladies I just let slip that secret my bad anyway now the interesting thing about Mac addresses is they're pretty guaranteed to be unique but the problem is even though they're unique they are not predictable which is why we only really use them for land communic ation and not internet communications IP
• 15:30 - 16:00 addresses are not unique as you've seen with what we've done previously with the ipv4 videos the nting all that good stuff but with ipv4 addresses they are predictable as long as I know what your address is I'm pretty certain of how I can use that to get traffic to you whereas a MAC address I've got to find out what it is at some point so let's understand why are they guaranteed to be unique well the ma is broken into two parts the first half the first 24 bits
• 16:00 - 16:30 or six heod decimal characters are called the oui or organizational unique identifier and the manufacturer of a network card or any network Appliance for that matter that needs a MAC address has to approach the I and a couple of other numbering and naming authorities to get that oui so if you go and buy a bunch of network cards from a particular manufacturer the chance of them having the same oui is pretty damn High especially if they're rolled off the same production line at the same time
• 16:30 - 17:00 now the reason why I say it's pretty damn high is because a lot of network card and network device manufacturers have several ois assigned to them but they have to use that particular string of 24 bits or six hex characters and the second half goes by a couple different names I've seen vendor assigned I've seen interface ID I personally hate that one and then the most standard name I've seen is the network interface controller specific portion which is unique to the network
• 17:00 - 17:30 Cod and one of the agreements that the manufacturer of the network Appliance has to abide by is that they will make sure that they give every network card they produce a unique Nick portion for the given oi that they were allocated so if we stick an example Mac address here 0017 c84 f30 F2 the first half is the oui and the second half the 4 F3 b0 F2 would be unique to that
• 17:30 - 18:00 Network Cod no other device should have that exact combination of oui and interface ID somebody else could be running around with an oui of 0017 C9 and still use for f30 F2 but it'll be unique still by one digit but there is a MAC address I know you will have in your network at some point and that Mac address is called the broadcast Mac address it is all binary one ones so it's 48 1es I'm not typing those all out
• 18:00 - 18:30 sorry I'm a bit lazy we can write it with 12 heximal FS it's the same thing and this is a MAC address that we use as a destination Mac address when we want to make sure the traffic goes everywhere switchers will see this Mac address and go okay I'm going to send this out of every single interface except the one arrived on so when I want to make sure traffic goes to everybody I use this destination Mac address
• 18:30 - 19:00 so now let's get into the switches properly so first of all let's look at what we already have hubs and bridges hubs have loads of interfaces but they've got absolutely no fording intelligence then you got the bridges they've got forwarding intelligence at layer 2 but they don't have that many interfaces that's the big downside of bridges so a bunch of network Engineers got clever they booked a hotel room and
• 19:00 - 19:30 put the Hub and the switch in that hotel room and they waited a long while and then after a long while out came a switch so the switch gives us loads of interfaces and every one of those interfaces has Layer Two forwarding intelligence like a bridge does now the way the switch will keep track of things is it's going to keep track of stuff with the MAC address table and it's going to associate Mac addresses it learns by looking at source Mac address fields of traffic just like the bridge did with the interface that it heard the
• 19:30 - 20:00 traffic on and Please be aware that the bridge can associate more than one Mac address with an interface looking at the switch over here it would have learned that PC's MAC address on that interface and at some point these two PCS would have sent something to that PC so that PC's traffic would have arrived there the switch would have learned it in that interface that PC would have sent something it arrived there the switch would have learned its source Mac address on the same interface so
• 20:00 - 20:30 switches can associate multiple Mac addresses with one interface please remember that it's just like the bridge the bridge remembered multiple Mac addresses per interface why shouldn't the switch now there's a bit more to switch logic that I want to teach you about such as switches will inspect the source Mac address of traffic arriving all the time and what it does is if the MAC address is new it adds it to the MAC address table Associated to that
• 20:30 - 21:00 interface if the MAC address is not new it moves on to a foring decision so the switches are always looking to learn whether it's been running for 5 minutes 5 hours or 5 years it will always want to check and see if it learns anything new then the switch will check the destination Mac address of the frame that arrived if the destination Mac address is present in the MAC address table the switch will only forward out of the interface that is associated with with that Mac address if the destination Mac address
• 21:00 - 21:30 is not present the switch does what's called a flood operation it'll send it out of every interface except the one it came in on this is usually done in the early stages of a switch starting up when the macadus table is still empty the MAC address table resides in the switch's RAM and is never saved to permanent non-volatile storage so power Cycles power trips physical resets will clear the MAC address aable so when the switch doesn't know it
• 21:30 - 22:00 sends it out everywhere in the hope that it gets the traffic to the intended destination and the destination generally would reply a lot of the upper layer protocols that we're going to get into in a later video but I did allude to them in the tcpip video are going to have some sort of response from the recipient so the switch is banking on that to see that Mac address coming back at some point so it learns it and can use it in the future and then do the more precise forwarding oper ation then the other situation is if the
• 22:00 - 22:30 destination Mac address is the layer 2 broadcast address of 12 hex decimal FS it floods it out of all interfaces except the one it came in on straight away it's not intending to learn with a broadcast the reason being the switch can tell when that's the destination Mac address the cender of that traffic wants it to get everywhere so let's have an example got nice little simple Network here with a switch in the middle it's got interfaces 01 02 03 we've got PCA PCB and
• 22:30 - 23:00 PCC a has got the IP address of 19216801 Mac address 01 02030 405 AA B's got the RP of 192168 0.2 Mac add s b b and c has the IP address of 192168 0.3 and the MAC address of blah blah blah CC and on PCA the user types in to their command line ping 92168 0.2 now ping is
• 23:00 - 23:30 just a simple layer 3 hello message sends a layer 3 message to the destination IP address and expects to get a simple hello back just checks basic connectivity so PCA starts constructing this ping packet it will populate the four key addresses destination Mac source Mac Source IP destination IP with what it believes to be the best information and obviously it starts out with Source information because obviously Source information belongs to
• 23:30 - 24:00 PCA source Mac address is 0 1 02 03 0405 AA Source IP is 192 16801 destination IP we get it from the Ping command 1921 16802 destination Mac address if PCA hasn't spoken to the destination it's going to have a bit of a problem because what it does is it checks say it's got called the op table the op table is the address resolution protocol table and it it keeps track of known IP addresses and
• 24:00 - 24:30 Mac address associations so in other words what Mac address is this person using and like I said if a has not spoken to B before this table is empty doesn't know anything so this ping packet is not going to work for now oh dear dear dear so we're going to get rid of it for now and we're going to introduce something that will allow a to find B's Mac address without knowing it at all we're going to generate what's called an OP request very similar Fields
• 24:30 - 25:00 source Mac 0 1 02 03 04 05 AA bcas Source IP 19216801 a 1921 16802 the person we're looking for Courtesy of the Ping command but this time we put the broadcast Mac address as the destination Mac address and the op request is basically message saying hey whoever's got this IP address please reply to me I want to know what your Mac address is so this broadcast now leaves the PC and
• 25:00 - 25:30 it arrives on the switch on interface 01 now the switch has got an opportunity to start populating its Mac address table so in this Mac address table is keeping track of his interfaces 0 1 02 03 and it goes o I've just received something new and let's check source Mac address 0 1 02 03 04 05 a a nope don't know that one so let me put it over here so that I now have it for future reference now let me check the
• 25:30 - 26:00 destination Mac address oh it's the layer 2 broadcast oh well no point me checking the MAC address table says the switch let me send that out of all of my interfaces so that it gets to everybody now that it goes out to everybody let's just get C out of the way c will check this and realize it's not meant for it c will see okay person that they are looking for is 1921 16802 I am 1921 16803 it's not me so it ignores this but PCB will see it PCB will say Okay
• 26:00 - 26:30 somebody with this Mac address and IP address is looking for this IP address oh that's my IP address and as an OP request they want to know what my Mac address is so B says all right I better reply to this person now B being clever will take this opportunity to populate its op table so that it knows okay that IP address is associated with that Mac address and then it starts crafting an OP response B will put in its op response its Mac address for the source
• 26:30 - 27:00 Mac its IP address for the source IP remember this is a response from B to a A's IP addresses the destination and remember it takes that requests source Mac address as a way to populate the destination Mac address for the response it's there in the art table as well now so now PCB can send its response that response now arrives on the switch the switch goes o I just received something on interface 02 let me check do I I know that source Mac address 0 1 02 03 04 05 BB no I don't
• 27:00 - 27:30 know it so the switch goes and puts that in the MAC address table associated with interface 02 then the switch goes and checks destination Mac address of this Frame 01 02 03 04 05 AA and it says yeah I've got a record there and if I send it out of interface 01 it should get to the recipient so let me do that says the switch and out it goes now PCA receives that op response
• 27:30 - 28:00 and goes ooh that person I was looking for has replied now I can see what their Mac address is and PCA can now put that record in its Mac address table now that the original PC has leared the MAC address of 1921 16802 it says okay now I can get that ping packet back and this time I can now put the destination Mac address in the dmac field 0 1 02 03 04 05
• 28:00 - 28:30 BB and this PC can at long last send the Ping the Ping arrives on the switch on interface 01 obviously the switch doesn't know it's a ping it doesn't care it just sees Mac addresses and it says oh I've seen this Mac address before so I don't have to worry about it and it's going to this Mac address and I've got that Mac address there so let me send it out of that interface so it's going to go out there now two PCB and by the way this example didn't just teach you how
• 28:30 - 29:00 the switch works and how the traffic is going to end up going around although it did actually but I also taught you how the address resolution protocol works this runs always when you don't know the recipient's MAC address this is how we can find out what the MAC address is despite it not being predictable we ask and the way we ask is by yelling out to everybody in the land hey who is responsible for this IP address I want to know what your Mac
• 29:00 - 29:30 address is that is basically what op does it goes and finds out what the unknown Mac address is with a known IP address now in this case we knew what the IP address was because of the Ping packet in other situations we might have used a host name or something like that and some name resolution servers like DNS would have given us the IP address and then op takes over once we've got the known IP address so now let's move on and look at a couple different types of switches you can get the first major
• 29:30 - 30:00 category you want to be aware of are managed and unmanaged switches now the key thing about a managed switch is this is the kind of switch that you can log into and configure things on it whereas an unmanaged switch it's a simple switch you plug it in you cable it up and it does its thing both switches will ultimately do the same stuff we've just looked at but a manage switch gives you access to a bunch of cool configurations and settings that we're going to look at with some later videos on more advanced
• 30:00 - 30:30 switch features so how do you tell them apart well on the left there you've got a manage switch and on the right there you've got an unmanaged switch and the way I know that the one on the left is a managed switch is that little interface there I've circled in red now I tried zooming in on this picture and sadly you can't see the writing so you have to take my word on it but that interface that's circled in red is labeled console soon as you see an interface labeled console or con or con zero that implies
• 30:30 - 31:00 that is the interface that you plug into to apply configuration you'll use one of those rs232 to RJ45 console cables or one of those rollover cables we spoke about in the cabling and connectors video to apply your config now don't worry if you've got an unmanaged switch it's just as good as a managed switch the any difference is you can't choose any settings but if you've deployed a manage switch and never ever applied a getting to it it's fine you cable it up
• 31:00 - 31:30 it does the basic switching like an unmanaged switch does you don't have to go and turn anything on but believe you me in an Enterprise environment the settings and features that are managed switch brings to the table are well worth it then we get desktop or small office home offer switches versus Enterprise switches now desktop switches are usually quite small compact run from one of those little DC power bricks or wool Walts as some people call them and usually have a couple interfaces very
• 31:30 - 32:00 rarely more than eight or 10 interfaces they're often also going to be a nice shape that's easy to have in the home environment it's not bulky it's not heavy it's easy to put out the way I've actually got one screwed to the back of my desk as part of cable management just so I can connect a bunch of things that I got sitting near me right now then you get Enterprise switches bit bulkier normally loads more interfaces but the key thing about enter PRI switches is they come in rack unit form
• 32:00 - 32:30 factors usually most switches like this one in the picture here are one rack unit high and you can put them in a network cabinet server rack whatever because again that one in the picture there is probably the 19 in wide it needs to be def a networking cabinet you sometimes do get slightly smaller Enterprise switches that aren't 19 in wide but they will normally come with very long armed brackets so you can mount them in a network cabinet or
• 32:30 - 33:00 server rack now yes I did reuse the managed switch picture but an unmanaged switch can also be in an Enterprise form Factory too then the next type you get are fixed and Chassis switches fixed switches like the unmanaged switch or the managed switch that we looked at previously have a fixed number of interfaces you can't change them it is what it is you get what you get if you wanted more
• 33:00 - 33:30 interfaces you should have bought the one with more interfaces if you've got too many interfaces you should have bought the one with fewer interfaces yeah know it's a bit brutal right but then you get that very elegant cool looking chassis switch over there what's going on there while that still mounts in network cabinets assuming you can Farm them big enough for that bad boy and obviously server racks and what happens is all of those interfaces there are removable cards you can take it out
• 33:30 - 34:00 and put maybe a better Processing Unit in or another fabric unit it allows you to decide how many interfaces what kinds of interfaces and how much processing power the switch is going to have now this is not your average kind of user land switch this is the kind of thing you'll find in data centers and cloud provider environments and ISP networks and stuff like that the these are pretty badass switches they're really cool and
• 34:00 - 34:30 they also have redundant power supplies as well because I mean when you got this level of coolness you don't want something as simple as a faulty power supply taking it down and they are very expensive I'll let you go do some homework on how much they cost just make sure you're sitting down when you check what the price is and then you're going to come across this thing called a stackable switch and that's what it looks like that just looks like a bunch of switches CA together
• 34:30 - 35:00 normally why is it stackable well switch stacking is going to use a special kind of cable and what it does is it allows you to get multiple switches usually manageable to work together as though they were a single logical switch it's a pretty cool technique but in my opinion you don't need to know much more other than that's what it is for Network plus because you are going
• 35:00 - 35:30 to want to try and stick to the same vendor preferably the same model of switch if you're going to do stacking and the reason why you want to do this is so that you can expand on connectivity and processing capability without having to go through the expense and challenges of getting a chassis switch because in some cases even the smallest chassis switch is overkill for what you need now knowing me I'm going to find a way to tell you more about stackable switches later on because I really dig networking and I want you guys to be
• 35:30 - 36:00 kickass at it but before we do that we need to draw a line for this video and as far as I'm concerned that's enough for the basics of switching for now but don't you worry we're going to come back to switchers more often with some of the more advanced features we'll talk about things like vlans span Tre protocol and some other cool things but for now I want to say thank you for watching if you enjoyed this and you got anybody you know that wants to also learn Network plus don't be afraid to
• 36:00 - 36:30 share this video with them otherwise though I catch you in the next video