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INTRO TO NETWORKS

1. Cisco Packet Tracer Software

In this video we will talk about Cisco packet tracer, which is a cross platform visual simulation tool designed by Cisco, allows users to create network topologies and imitate modern computer networks. This software allows users to simulate the configuration of Cisco routers and switches using simulated command line interface. Packet tracer makes use of a drag and drop user interface, allowing users to add and remove simulated network devices as they see fit. We are going to use the Cisco packet tracer in this course for hands-on experience with Cisco routers and switches. Guys, in this video we will see how to download and install cisco packet tracer on your computer. On later sections of discourse. We have got lots of Cisco packet tracer labs. When you get one of these labs, youkan download the put files from the files FM link that you can see on screen. Now that I used to create that lab lessons and load those files on your computer. That is going to give you the base topology and the base configuration that you are going to work with. You can watch the lab lesson and after that you can do the lab on your own. And this is going to give you a great hand on experience on Cisco switches and router skies. Now let's see how packet tracer is downloaded and installed on our computers. Okay, we simply type the Cisco packet tracer download and we get the net account link. Okay, once we click on we can see the enrol to download packet tracer button. Simply just click on this one and sign up today. Okay, now we need to enroll and we just type our iPad first name and the network e l and last name nice mail will be network and we have a simple math question. Then just click on the submit. Okay, once we click the submit button, we are receiving an email which includes the activation link inside. I think we need to refresh in our email. We just click to activate account button and there’s form that we need to fill up. Okay, we just choose a country region and we just define a password for our network account. This is one I think I'm not good at reading captures. Okay, then just click on the register button and we are automatically redirected to the login page. On the login page we are typing our email. Click next, then we are typing our password. Then sign in. Okay, this is redirecting to another page and there is a forming here also that Cisco wants us to fill it up. Okay, we choose mail state and more than five years. We prefer not to say birth date. I’m not so young so we can choose this one. Okay, just click on the create account. We can just click on launch cars. Okay, we are now enrolled the introduction to packet racer cars. You can even also enroll in here and check in detail if you want, but I'm already going to show you the details about the Cisco Packet Tracer in our training. Okay, so how to download this one? Once we type the same thing, we are already enrolled. We can simply log into NetAcad. Okay, once we log into NetAcad, now we can see in here there's a resources field. On the resources field, you can simply choose the download packet tracer. Okay. And there's a download link in here you can find for Windows and Linux and Mac OS also. Okay, once we click on the download button, now we can choose to run. Okay, once our download finishes, we will have a screen that shows us step by step how to install the packet tracer. So we need to accept the agreement first, then we choose destination. Okay, next and just install. There we go. It won't take a lot of time, I think. Come on. Okay, it's just there. Then just click on finish and there we go. Here is the packet, Tracer. But first, before using the packet traysr, it is going to ask the account that we already created. Okay, first we need to log into our account again to use the packet tracer, even on our computers. Okay, so we enter our credentials again and there we go. Here is the Cisco packet. Tracer screen. Okay, this is a really good and powerful tool that helps us to simulate our network devices such as routers. For example, we have routers in here, okay. And these are the router modules that we can use on Cisco Packet Tracer. And we have switches we can use. And we have hubs, we have wireless devices, security devices. We have some wide area network emulation. And if you just want to use a router, just click on that one and drag and drop to the white area. Okay, here is the router that we can use. And if you want to use another one, you can also just drop it here. Okay. And simply we have two routers now. Okay, once we click double click on the router, you can see the physical view of the router itself. Okay, here is the front view of the Cisco 2911.And here is the rear view of the device itself. So you can zoom in and check the interfaces of the device. Also then you have an option to config. And here is the menu that we will use. Mostly that is the CLI. Okay, here is the CLI menu that will help us to configure Cisco router. This is a simulation tool, but the commands that we can use are the same with as a physical Cisco router device. Okay, for example, we have some router in here. I will show you everything in detail how to configure this kind of devices. So this is just an introduction, guys. Then we have another router in here. So if you want to connect these guys to each other, here is the cabling. We have some connection methods so you can choose. For example, we will use the Gigabit Ethernet and Gigabit Eternal Zero for each site so we can connect these guys to each other also. Okay, that's a really cool feature. Then we can also add another device. For example, we can add a switch to our topology and even we can also add a PC. Okay, that's really cool. So let's check what's going on between these guys. We can connect our switch to our router and we can connect our PC to our switch. Then let's check what we have on a PC so you can again zoom in and zoom out for a PC. And even in here you have some options. Okay, so you can use the IP configuration in here and you can simply define the IP addressing parameters of a PC in here. All right, we're now able to drag and drop some devices and what we can do firstly what I can suggest you is just options and preferences and always show port labels in logical workspace. That's a really helpful feature. So you can easily see the interfaces that you use to interconnect your devices each other. Okay, so click on the switch also. And this is a switch. Cisco switch. And this is the physical view of this switch. You can see it has got some ports and some buttons in here. So to configure this guy you can just click on the CLI itself and let's do the first configuration. I can hear you. You want that? Okay, I'm going to show you just really simple thing, okay. The simplest thing but doing something will give you some confidence and you will see how easy it is. Okay, just click on Enter and let's change the name of host name of this device. You can see our switch named switch as default. So I'm going to just change my switch name to something different. Okay, we just need to go to the enable mode first. Okay, I'm going to tell you the differences between different CLI modes. Okay, so just go to the Configmode by typing Configure terminal mode. This is the mode that we are using to make our configurations. Okay, if you want to just change something on the device you need to go to the configuration mode. Okay, but if you want to go back to the Enable mode, just type exit on enable mode. You cannot make any configuration but you can make some monitoring, you can run some show commands. Okay, just go back to the Configure terminal and to change the host name our command is Hostnamehostname and we just define it as Networkl. Once we click the enter immediately we can see that our host name changed to Network. Okay, that's really cool. I really like packet tracer and during our training we have got really exciting labs for you and you will get all of this kind of CLI hands on experience. No worries on rries on tha Okay. Once you accomplish this lesson, Udemy will ask for a review of the course. Okay? And if you just enjoyed the training until now, please rate it with five star. That would be perfect for us. Yes, I know it's a little bit early, but this is how Udemy works. And please rate the training if you enjoyed it with five star. And on the other section, we'll going to do Introduction to Networks.

2. Introduction To Networks

So it's time to start now and let's go ahead with our first section introduction to Networks. In this section we are going to talk about basics of network lance, Winds and the Internet and network trends and security overview. All right, let's go. We are starting our training with an interesting graphic. This graphic shows us number of devices connected to Internet worldwide. As you can see, there were eight billions of devices connected to Internet, but it is assumed to be 50 billion. That is a really crazy number guys. And that means we will need much more resources such as bandwidth and stronger devices and more secure networks. Let's go ahead with the global community networks. Nowadays we may often need to meet people from different parts of the world. Especially global companies can often hold meetings with employees in different locations. However, it can be very difficult for all employees to come together at the same location for each meeting, both in terms of time and cost. Cisco has two great solutions for eliminating these time and cost problems. The first solution is video conference. Video conferencing is a technology that allows users indifferent locations to hold face to face meetings without having to move to a single location together. This technology is particularly convenient for business users in different cities or even different countries because it saves time, expands and hassle associated with business travel. The second technology we are going to focus on is telepresence. Videoconferencing technology isn't always able to dissolve barriers and facilitate remote collaboration. Cisco Telepresence recreates the meeting room experience so you can meet face to face with your globally dispersed teams. Now in person meetings can be happened without the hassle of travel so you can be more available and more effective than ever before. The Cisco telepresence experience delivers high quality audio and high definition video over a reliable IP network. Unlike video conferencing, your meetings will look and sound as if all the participants are actually together in the same room. Here is the telepresence device. As you can see in here, these guys are may be in Paris and these guys are for example, in Tokyo. But what they feel is as you can see, they are on the same table. That's a really great and cool technology. Now let's talk about the variety of networks according to their size. Small home office networks are networks of several PCs, laptops and printers and it means basic requirements such as surfing on the Internet. For example, medium-sized networks usually consists about 15 or20 PCs, laptops and just a few printers. Maybe in these networks also a network device such as switch or router can be used, which we will see in more detail later. And let's go ahead with the large and worldwide network. Large networks are geographically distributed networks. In such networks, very powerful network devices are used to provide communication between the ends. A simple example of these networks is simply internet or we can think about a global company such as Cisco, and Cisco uses the large networks to provide communication between different locations such as Cisco, Australia, Cisco, Poland, San, Cisco, China, and etcetera. Between different buildings. Let's take a look to client and server concepts. Now, these guys are the clients and this guy is the server. Clients are the devices such as PCs, smartphones, and laptops that request a service from the servers. And servers are the devices that provide requested service to the clients. Servers are classified by the service they provide. For example, a web server serves a web page, a file server serves computer files, and something like that. The client established a connection to the server over a local area or wide area network, such as the Internet. Maybe once the server has fulfilled the client's request, the connection is terminated. For example, let's say that this PC wants to connect with the Google's Web page. And let's say that this is the web server of the Google. If you want to connect Google's Webpage, your PC is the client which requests the web page, and Google's Web server provides you the request service which is a web page for this situation. And let's go ahead with the landscape and the Internet. Let's first talk about the devices that we can use in our network. There are two types of devices and there are ant devices and the infrastructure devices. The network devices that people are most familiar with are called end devices or hosts. These devices form the interface between users and the underlying communication network. Some examples of end devices are computers, network printers, VoIP phones, telepresence, endpoints security cameras, and something like that. Infrastructure devices are the devices that helps to provide communication between different end devices. For example, you can communicate different PCs by using switch on the same local area network. As an example, we can give switch access points, routers, and firewalls to the infrastructure devices. And let's go ahead with the network media. Network media refers to the communication channels used to interconnect nodes on a computer network. In a network, we can provide communication in two ways, and they are wired and wireless. In a wide media, we use different types of cables such as copper cable or fiber optic cable, to provide communication between different devices. Wireless network media provides communication between two or more networking devices that are not connected by a cable. The most common wireless technologies use radio waves. With radio waves, distances can be short, such as a few metres for Bluetooth or as far as millions of kilometres for deep space. Radio communications and network infrastructures can vary greatly in terms of size of the area covered, numbers of the connected users, numbers, and types of services available. Basically, we have four types of networks and they are local area network, wide area network, metropolitan area network, and storage area network. Local area network is a network infrastructure that provides access to users and end devices in a small geographical area lands interconnect end devices in a limited area such as a home, school, office building or campus. Ln is usually administered by a single organisation or the individual. Let's go ahead with the wider network. Wider a Network when is a network infrastructure that provides access to other networks over a wide geographical area. This is the difference from the local area network. Vans are typically managed by service providers or Internet service providers and they interconnect different local area networks over wide geographical areas such as between states, provinces, countries or something like that. In the figure you see a Van infrastructure and here there's a London office, in here there's a Dallas office, in here there's a Washington office, and in here there's a Berlin local area network and widery network interconnects these different local area networks between different countries. Let's go ahead with metropolitan area network. A man is a network infrastructure that spends a physical area larger than a local area network but smaller than a wide area network. Men's metropolitan array networks are typically operated by a single entity such as a large organization. A storage area network is a network infrastructure designed to support file servers and provide data storage, retrieval and replication. It involves high end servers, multiple disk arrays and fiberchannel interconnection technology. Although there are benefits using local area network or wide area network, most individuals need to communicate with a resource on another network outside of the local network within the home, campus or organization. This is done using the Internet. The Internet is a worldwide collection of interconnected networks cooperating with each other to exchange information using common standards through telephone wires, fibre optic cables, wireless transmissions and satellite links. Internet users can exchange information in a variety of forms. But how we can connect to internet? We have some options for this. The first option we are going to check is DSL digital Subscriber Line technology. Digital Subscriber line is a family of technologies that are used to transmit digital data over telephone lines. In telecommunications marketing, the term DSL is widely understood to mean ADSL, the most commonly installed DSL technology for Internet access. DSL service can be delivered simultaneously with wired telephone service on the same telephone line. Since DSL uses higher frequency bands for data. Here is how we can connect to Internet by DSL. Here is your computer device and you connect your computer's network interface card to a device named Moda. This modem device is connected to a little device, little equipment named which splits the telephone and the data frequencies. The other side of the splitter is connected to your phone and splitter is connected to a device named DSLR. On the ISP side, Slam is connected to ISP backbone and this backbone takes you to the Internet simply. You can also connect to Internet by using cellular or mobile network. A cellular network or mobile network is a communication network where the last link is wireless. The network is distributed over land areas called cells, each served by at least one fixed location transceiver. But normally three sales sites are base transceiver stations. The most popular cellular networking communications are three G, four G and that's going to be 5G in the future. Satellite Internet access is the internet access provided through communication satellites. Modern consumer grade satellite internet service is typically provided to individual users through geostationary satellites that can offer relatively high data speeds up to 50 megabit per second. And here is how we can connect to internet by using satellite. Here is our PC and our PC is connected to satellite router. This time satellite router is connected to antenna and these antennas are communicating each other by using satellite. This satellite forwards packets to internet site and you can access the internet by using this antenna and NOC hub. Another Internet connection option is Metro ethernet. Metro internet network is a metropolitan area network that is based on Ethernet standards. It's commonly used to connect subscriber to a larger service network or the internet. Businesses can also use metropolitan area Ethernet to connect their own offices to each other. And in the third step we'll talk about network trends and security overview. The first trend we are going to talk about is Dyod bring your own device. Bring your own device refers to the policy of permitting employees to bring personally owned devices such as laptops, tablets and smartphones to their workplace and to use those devices to access privileged company information and applications. And let's go ahead with another trend, which is online collaboration. Simply put, online collaboration lets a group of people work together in real time over the internet. Those engaged in online collaboration can work together on word processor, documents, PowerPoint, presentations and even for brainstorming all without needing to be in the same room at the same time. The another trend is cloud computing. Cloud computing is the delivery of competing services such as service storage, databases, networking software or something like that over the internet, which is known as the cloud. Companies offering these competing services are called cloud providers and typically charge for cloud computing services based on usage similar to how you are built for water or electricity at home. Instead of having to invest heavily in data centres and servers before you know how you are going to use them, you can only pay when you consume competing resources and only pay for how much you consume. And let's go ahead with the data centers. A data centre is a facility composed of network computers and storage that businesses, business or other organisations use to organize, process, store and disaminate large amounts of data. Data centres are not a single think guys, but rather a conglomeration of elements. At a minimum, data centres serve as the principal repositories for all manner of It equipment including servers, storage, subsystems, networking, switch, routers and firewalls as well as the cabling and physical racks used to organize and interconnect the IT equipment. A data centre must also contain an Etiquette infrastructure such as power distribution and supplemental power subsystems, including electrical switching, uninterruptable power supplies, backup generators, and so on. Weinstein and data centre cooling systems such as computer room, air conditioners, and dedicated provisioning for network carrier connectivity. And let's take a look at the smart houses. A smart home is a residence that uses Internet connected devices to enable the remote monitoring and management of appliances and systems such as lighting and heating. Smart home technology, also known as the home automation, provides homeowners security, comfort, convenience and energy efficiency by allowing them to control smart devices, often by a smart home application on their smartphone. For example, when you are outside on a hot summer day, you can cool your home by running the air conditioner remotely by using your smartphone. And another trend is power line networking. Powerline networking, as its name implies, uses your existing electrical power cabling to transmit digital data. In this case, it is used to transfer your networking data. This can essentially be thought of acting like a wire network where your electrical wiring replaces a large segment of unsightly Ethernet cable. Power line networking is a good alternate that can often be used in situations where wiring is difficult and let's go Ahead with the Network Security Threats Guys it's a dangerous world out there in the World Wide Web. Just as your mother may have told you to never talk to strangers, the same advice holds true for the virtual world. You may not be wary of giving strangers your business bank account details, but can you be sure website you are logging into is that of your bank and not a forgery created by a cybercriminal? Cybercriminals use a variety of methods to entice you into disclosing confidential, personal, or business information. As a small business doing business on the web, you need to be aware of these methods so you can be extra vigilant when online. The most common network security threats you can face are Dos attacks, viruses, worms, malware, spam, phishing, and similar. We'll go over these concepts in greater detail in later lessons.

3. Network Protocols

In the section we're going to talk about network protocols. Let's start with network message. Delaware options to Delaware message on in a network we have three options unicap, broadcast, and mouthcast. Unicast is a term used to describe communication where a piece of information is sent from one point to another point. In this case, there is just one sender and one receiver. Broadcast is a term used to describe communication where a piece of information is sent from one point to all other points. In this case, there's just one sender, but the information is sent to all connected receivers. Mouthcast is the term used to describe communication, where a piece of information is sent from one point to a set of other points. In this case there is sender and the information is distributed to a set of receivers. Let's explain these network message delivery options with an example. For example, let's say that here is an apartment and let's say your friend Sally lives in here. You want to visit Sally, you come to entry of the apartment and if you just ring the doorbell of Sally, if you just wrinkle doorbell of Sally, that is unicast. And let's say that in this apartment we have also Hillary and John is living. If you ring the doorbell of Sally and Hillary, if you ring the doorbell of Sally, Hillary and Jonah also this is broadcast. In the broadcast, you disturb Hillary and John, as youkan see, because you will go to Sally's home. That's the difference. That's the key difference. Let's go ahead with network protocols overview A protocol is a set of rules that governs the communications between computers on a network. As you see on the screen, these rules include guidelines that regulate the method of access, types of cabling, and speed off sized data transfer, and let's go ahead with the standards organization. A standards organization, sometimes referred to as a standards body, is an organisation with authority to endorse official standards for given applications. The most important standards organisations are let's go ahead with Protocol Suits. A protocol suite is a set of related protocols that work together in the context of a local Sergio protocol stack. For example, the TCP IP Protocol Suite, which is the basis of the Internet, is a collection of related protocols that are used in various combinations to serve specific applications. TCP IP Protocol Suit is the conceptual model and set of communications protocols used on the Internet and similar computer networks. The Internet protocols to it provides end to end data communications, specifying how data should be packetized addressed, transmitted, routers, and received. This functionality is organised into four abstraction layers which classify all related protocols according to the scope of networking in one from the lowest to highest. The layers are the Network Access Layer, Internet Layer, providing Internet working between independent networks, transport layer, handling host to host communications and the Application Layer, which provides process to process data exchange for the applications and let's go ahead with the OC Reference model. OSI module is a reference module created by ISO for how applications can communicate over a network. It conceptually divides computer network architecture into seven layers in a logical progression. Before OSI guys, it was almost impossible to create a communication between different vendor devices. For example, an IBM device could just operate with another IBM device. The purpose of OSI Reference module is to guide vendors and developers so the digital communication products and software programmes they create will interoperate. And to facilitate clear comparisons among communication tools, most vendors involved in telecommunications make an attempt to describe their products and services in relation to the OSI module. Today. Many vendors. For example, Alcatel, Huawei, Cisco, IBM and Etcetera. Can operate each other by the help of the OSI module. Here, as you can see, OSI consists of seven layers and they are physical Data, Link, Network Transport, Session, Presentation and the Application. We are going to talk much deeper about eachlayer on our later lessons and let's compare this. OSI and the TCP IP Modules. There are some key differences between OSI and TCP IP Modules. TCP IP has four layers, as you can see in here application Transport, Internet and the Network Access. But OSI module has seven layers. TCP IP makes no assumptions about what happens above the level of a network session part of OSI layer Five while OSI defines several more layers of standardised functions, TCPIP makes no prescriptions as to the link layers belowIP, while OSI specifies two layers. If an application needs functions not found in TCP IP, the application has to supply them in the OSI module. It is assumed an application will never implement any functionality belonging in any defined layer, and because interfaces between layers abstract many details, it may not be able to anyway. And let's go ahead with the moving data in our network. When data moves from upper layer to lower level of OSI, each layer includes a bundle of relevant information called header along with the actual data. For example, let's say that PCA wants to communicate with PCV and this guy is the sender and this guy is the receiver. While PCA is sending a packet to the PCB, eachOSI layer will add their headers to the data. For example, Presentation layer will add its own header, transportation layer will add its own header. Network layer will add its own header and accelerate the data package containing the header and the data from the upper layer then becomes the data that is repackaged at the next lower layer level with lower layers. Header is the supplemental data placed at the beginning of a block of data. When it is transmitted, this supplemental data is used at the receiving site to extract the data from the encapsulated data packet. This packaging of data at each layer is known as the Data Encapsulation. Encapsulation is being received on this way. The reverse process of encapsulation is their encapsulation, and their encapsulation occurs when data is received on the destination computer. As the data moves up from the lower layer to the upper layer of OSI, each layer unpacks the corresponding header and uses the information content in the header to deliver the packet to the executive application waiting for the data in here, what is going to be is that, for example, packet data is encapsulated in here with the headers and in here. This time, each layer will unpack the data and will deencapsulate it completely. Let's go ahead with the Protocol data Units A protocol data unit is information delivered as a unit among peer entities of networks containing control information, address information, or data in layered systems. PDU represents a unit of data specified in the protocol of a given layer, which consists of protocol, control information and user data. PDU is significant term related to the initial four layers of the OSI module in layer one and in here PDU is a bit. As you can see, these are the bits. In layer two, our PDU is frame. In layer three, our PDU is a datagram, and in layer four our PDU is Segment. Let's go ahead with the Mac and IP address terms. A medium access control Mac address of a device is a 48 bit unique identifier assigned to network interfaces for communications at the datalink layer of a network segment. Mac addresses are used as a network address for most network technologies, including Ethernet and WiFi. An Internet Protocol IP address is a numerical label assigned to each device connected to a computer network that uses the Internet Protocol for communication. Having an IP address allows a device to communicate with other devices over an IP based network like the Internet. As you can see in here, Mac addresses work on OSI layer two, but IP addresses operate at OSI layer three. Mac addresses are 48 bits. Length IP addresses may be 32 or 128 bits. If it's IPV four, it's 32, if it's IPV six, it's 128.IP addresses are shown in decimalor hexadecimal format, but Mac addresses are just shown in hexadecimal format. Here is an example of a Mac address, something like that, as you can see. And here is an example of the IPV four address. We are going to talk much deeper about Mac addresses and IP addresses also in our later sessions. And let's go ahead with the ARP request address resolution protocol. ARP is a telecommunication protocol used for resolution of IP addresses into Mac addresses. For example, if host A wants to communicate with the100 zero true PC by using the same switch, host A needs the Mac address of the device, and for this purpose, host A sends an R prequest. Here is the details of the app request. Host A says that hey, I want the Mac address of who is 100 zero two. Tell me your Mac address. This guy takes the request and replies back with an RPI. And this RP packet includes the Mac address of this PC. Here is the information included in the RPY. Hey, here is my Mac address. I am two. That's me. And here is my Mac address. If you want to communicate with me, you can use my Mac address. All right, let's talk about how we can communicate in the same network. Communication in the same network is made over Mac addresses between devices, and packet is not sent to default gateway, which is the interface of a router. We are going to see this guy and how this operates deeply again later sessions. But please keep in mind that if you want to communicate by using the same switch, for example, if PC One wants to communicate with the FTP server in here, the communication is made over just Mac address. But if you want to communicate with the remote network, packet is sent to default gateway of the client if a communication is wanted. All right, what we're going to make in here? If PC One wants to communicate the web server on the remote side, the packet will be sent to the default gateway, which is this interface of this router device. All right, guys, I know that we don't still know what a router is. We don't still know what a default gateway is also, but just please keep in mind what is going on. I'm going to explain all of these guys to you step by step on the other sessions, all right? And if PC Two also wants to communicate with the Web server, this guy should also send a packet to the default gateway. All right? That's the thing that we need to really focus on. If you want to communicate with a remote network, you are sending the packet to the default gateway. If you want to communicate with the internal network, there's no problem. By using a single switch, your communication is just made over the Mac addresses.

4. Network Access

In this section we are going to talk about network access and we are gonna define how we can access to a network. Briefly first we are going to take a look to physical layer overview of OSI. Then we are going to talk about network media. And lastly we are going to talk about data link layer protocols and media access control in this lecture. Firstly we are going to focus on OSI. Layer one physical layer in the seven layer OSI module of computer networking. The physical layer or layer one is the first and the lowest layer. The physical layer consists of electronic circuit transmission technologies of a network. It is a fundamental layer underlying the higher level functions in a network. The physical layer defines the means of transmitting grow bits rather than logical data packets or a physical datalink connection network notes the bit stream may be grouped into code words or symbols and converted to a physical signal that is transmitted over a transmission medium. The physical layer provides electrical, mechanical and procedural interface to the transmission medium. And here are the fundamentals of the physical layer. We have three medias. The first media is copper cable, the second media is fiber optic cable and the third is the wireless media. In a copper cable media the physical components are maybe a UTP cable coaxial cable we have some connectors, we have network interface cards, ports, interfaces and etc. In a fibre optic cable media we have single multimodal fibres connectors, again network interface cards, interfaces, lasers and less and photoreceptors. And in a wireless media our physical components are maybe access points, maybe again network interface cards which are the wireless network interface cards this time maybe radios and the antennas. Bandwidth is the bit rate of available or consumed information capacity expressed typically in metric multiplications of bits per second. For example an internet connection with a larger bandwidth can move a set amount of data much faster than an internet connection with a lower bandwidth. Here as you can see the aberration of the as well if you want to talk about the kilobits per second we are using Kbps. If you want to talk about the megabit per second we are using the Gbps. Let's move forward with the network media. Network media refers to the communication channels used to interconnect nodes in a computer network. Typical examples of network media includes copper coaxial cable, copper twisted pair cable and fibre optic cables used in wired networks and radio waves used in wireless data communication networks. Let's go ahead with the UTP cable first I shielded to it appear UTP is a type of copper cabling used in telephone wiring and the local area networks inside a UTP cable is up to four twisted pairs as you can see in here. Here as you can see, the pairs are twisted to each other and we have anklosin a protective plastic cover with a greater number of pairs corresponding to more bandwidth. The two individual wires in a single pair are twisted around each other and then the pairs are twisted around each other as well. This done to reduce crosstalk and electromagnetic interference, each of which can degrade network performance. Each signal on a twisted pair requires both wires and here are the standards when we are using the UTP cabling UTP categories are starting with the cat one and finishing with the cat seven. We have various data rates for each categories as you can see. For example, if you are using cat one you can use up to 1 Mbps. But if you're using cat seven cable you can use up to ten gigabit per second data rates. The maximum lengths are almost the same as you can see, it's almost 100 meters. And the applications that are using the different categories are for example cat one is used in old telephone cables, cat two is used in the talkering networks. For example, cat six is being used gigabit and ten gigabit ethernet networks. Let's go ahead with the UTP connectors. Connector is the part of a cable that plugs into a port or interface to connect one device to another. Most connectors are either mail containing one or more exposed pins or female containing holes in which the male connector can be inserted. The RJ 45 connector is an eight wire connector that is commonly used to connect networking devices such as switches, routers or PCs to a local area network. This connector is used with cat five or cat six cables commonly and consists of eight pins. Here is the male connector and here as you can see, this is a female connector. Let's go ahead with the UTP cable types T five six eight A and T five six eight B are the two color codes used for wiring eight position RJ 45 modular plugs. The only difference between the two colour coats is that the orange and the green pairs are interchanged. Straight through cable is a type of cat five which the RJ 45 connectors at each and have the same pinout colour code used on both ends are the same. Straightrode cable is also referred as a patch cable. Straight through cable is used to connect computers and other end user devices to networking devices such as hubs and switch. Across cable is a type of cat where one end is T 56 eight A and configuration and the other end is TF 568 B configuration. Pin one is crossed with pin three and pin two is crossed with pin six. Crossover cable is used to connect two same devices for example router to router connection. Here as you can see the T five six eight pinauts and as you can see we have eight pins in here. If you're using this pin out with T five six eight A in the first pin you're using white green cable, in the second you're using green, third white, orange, blue, white, blue, orange, white, brown and brown. If you are using T five, six, eight Bin the first pin, you're using white orange cable this time, then orange, white, green, blue, white, blue, green and white, brown and the brown. Let's go ahead with the shielded twisted pair. Cable. Shielded Twisted Pair is a special kind of copper cable used in telephone or local area network systems and other covering shell. This guy is added to the ordinary twisted pair wise to prevent electromagnetic interference and the shield functions as a ground in here. Corkshield Cable is a type of copper cable specially built with a metal shield and other components engineered to block signal interference. It is primarily used by the cable TV companies to connect their satellite A ton of facilities to customer homes and business. Some homes and offices use corexuals cable too, in their locker in the network. But it's widespread. Use as an Internet connectivity medium in enterprises and data centres has been supplemented by the deployment of three suppair cable. A fibre optic cable is a network cable that contains strands of glass fibres inside an insulating casing. They are designed for long distance, very high performance data networking and telecommunications. Compared to white cables, fibre optic cables provide higher bandwidth and can transmit data over longer distances. The two primary types of fibre cables are called single mode and the multimode fiber. Single mode fibre uses very thin glass strengths and laser to generate lights, while multiple mod fibres use LEDs. Single mod fibre networks often use wave division multiplexing techniques to increase the amount of data traffic can be sent across the stream. As I told you, multimode fibres use Led a slight source and provide multiple pads for light. If you compare with the single mode, they provide lower bandwidth and higher Attenuation. And here are the connection types that we can use in the fibre optic cables. We have LC connector, SC connector, SC connector, FCconnector, Ntrj Mune 2000 connector types and let's compare the fibre optic with the copper cable. As you can see in here. The first, let's take a look at the distance. Optical fibre can DeProy up to 12 miles, while copper provides communication up to 300ft.The width is almost four lbs inhere, while the copper is 39.The maximum bandwidth that optical fibre can provide69 terabytes per second, which is much higher than the ten gigabit per second. But optical fibre is hard to tap and easy to alarm. But copper emits the EMI electromagnetic interface. Let's go ahead with the wireless communication. Wireless communication is the transfer of information between two or more points that are not connected by a cable. The most common wireless technologies use radio waves. With radio waves, speeds may be as low as three megabits per seconds for Bluetooth, for example, or maybe really high. Up to one gigabit per second for the Y Max technology. And let's take a look to 800 and211 WiFi standards these standards are set of Media Access Control and physical layer specifications for implementing wireless local area network communication. In the chart you can see the evolution of the standards. In the first standard, which is eleven, maximum data rate is two megabits per second. But in the eleven AC standard, which is the latest standard, the maximum data rate is seven gigabit per second. And in here you can see the frequency bands, bandwidth modulation types and advanced Antonio technologies for each standard as well. Let's go ahead with the data link layer protocols and media access control. Now, the Data Link layer or layer two of OSI is the second layer of the seven layer OSI module of computer networking and provides access to media via Mac addresses. Guys, this layer is the protocol layer that transfers data between adjacent network nodes. The datalink layer provides the functional and procedural means to transfer data between network entities and might provide the means to detect and possibly correct errors that may occur in the physical layer. Protocols like Ethernet, PPP and HTLC operate at this layer. The most important standards used in layer two are Ethernet, for example Y Max Bluetooth which are created by Itut and we have HDLC and Mac which are created by ISO and we have FTDI which is created by NC. These are the most important ones. The data Link layer functionality is usually split into two logical sub layers. As you can see, we have logical link control and media access control. The upper sub layer termed as LLC Logical Link Control that interacts with the network layer Elbow and the lower sub layer termed as Mac Mini Access Control is the one that interacts with the physical layer below. While LLC is responsible for handling multiple layer three protocols like Multiplexing and Multiplexing and the link services like Reliability and Flow Control, the Mac is responsible for framing and the MediaAccess Control for broadcast media. Ethernet is the most widely installed local area network technology guys. Ethernet is a protocol in the describing how network devices can format data for transmission to other network devices on the same network segment and how to put that data out of network connection. Ethernet defines two units of transmission packet and frame. The frame includes not just the payload of data being transmitted, but also addressing information, identifying the physical media access control, Mac addresses of both sender and receiver VLAN tagging and quality of service information and error correction information to detect problems in transmission. Each frame is wrapped in a packet which affixes several bytes of information used in establishing the connection and marking where the frame starts. Another protocol used in the data linklayer is the point to point protocol. Point to point protocol is a layer two communications protocol used to establish a direct connection between not we can use in here. For example, these devices are routers. For example, it connects to routers directly without any host or any other networking device in between it can provide connection authentication, transmission, encryption and the compression. And lastly we are going to focus on topologies. So what is a topology? A network topology is the arrangement of a network including its nodes and connecting lines. There are two ways of defining network geometry and they are the physical topology and the logical topology. Here we are seeing a physical topology. Physical topology is the placement of the various components of a network including device location and the cable installation. Here we can see a physical topology and what we are seeing is just the cable connections and name and symbols of the devices as you can see for example, we have an Apple iMac connected to Gigabit switch. We have an iPad which is connected to Apple Airport Extreme. We have an iPhone also connected to Apple Airport Extreme and we have two premiere which are connected to our gigabit switch. We have a printer in here which is connected to gigabit switch and etc. That's the physical view of the topology. We have three types of physical local network topologies and they are ring, bus and the star. In the ring network topology the workstations are connected in a closed loop configuration as you can see in here, other pairs of the workstations are indirectly connected the data passing through one or more intermediate nodes. For example, let's say that here is the PCone wants to communicate with the PC two. Here is the direction of the PC one is going to this guy, them, this guy and this guy. But what if this guy fails? If this guy fails, if there's an interruption on this guy, you can send a packet also from this way under Ring topology in the Bus number topology every workstation is connected to a main cable called the Bus. Therefore in effect each workstation is directly connected to every other workstation in the network. As you can see in the start topology there's a central computer server this guy to reach all the workstations are directly connected. Every workstation is indirectly connected to every other through the central computer. Here for example, if this PC one wants to communicate with the PC two, that should send the packet to this guy and this guy should forward the packet to PC. Okay, that seems like good, but if there's a problem on the central device, all the devices will fail as you can see. And here are the physical wider network technologies. Point to Point Topology is the first one, that's the simplest topology with a dedicated link between two and points as you can see. The second one is Hub and Spark Topology hub and Spoke here in a hub and spoke wider in Octopology, one physical site acts as the hub while other physical sites act as the spoke. Spoke sites are connected to each other via hub as you can see in here and in hub and Spoke wider network topology. The network communication between two spokes always travel through the hub and here is the lastly, we are going to focus on full mesh topology. Full mesh topology connects each node to all other cluster nodes. This topology is highly reliable and fast but it does not scale well. It is reliable because it provides many pads through the fabric in case of cable or not failure. It is fast with low latency because you can get to any node in the fabric in just one hop. It does not scale well because each additional node increases the number of fabric links and switch parts exponentially. As you can see in here, for example, we have router one, router three, router two, three, four and five and they are connected each other and that provides really big reliability. In this network there's a really big redundancy. For example, if router one wants to communicate with router two, this path can be used, this path can be used or this path can be used. We have various phase as you can see. So that means no matter if this link fails, the traffic will go through from here, from here, from here or something like that. And lastly we are going to talk about logical topology. Logical topology is the arrangement of devices on a computer network and how they communicate with another logical topologies describe how signal acts on the network. In a logical topology we can see IP addresses, as you can see in here, we can see tunnel types, we can see subnet mask and something like that. That's the logical view of the topology.

5. Ethernet

In the section, we're going to talk about Ethernet. As we discussed in our previous section, Ethernet is the most widely installed local area network technology. Ethernet is a protocol in describing how network devices can format data for transmission to other network devices on the same network segment, and how to put data on our network connection. Again, as we talked before, datalink layer has two sub layers and their LLC logical Link Control and Macmille Excess Control. LLC organises communication with upper lower layers and provides common interface reliability and flow control, and Mac appends physical address to frame and provides data encapsulation and error detection. Let's go ahead with the collision domain term. A collision domain is a network segment connected by a shared medium or through repeaters, where data packets may collide with one another while being sent. A network collision occurs when more than one device attempts to send a packet on a network segment. At the same time, members of a collision domain may be involved in collision with one another guys. Only one device in the collision domain may transmit at any one time, and the other devices in the domain listen to the network and refrain from transmitting while others are already transmitting in order to avoid collisions. Because only one device may be transmitting at any one time, total network bandwidth is shared among all devices on the collision domain. Collisions also decrease the network efficiency on a collision domain, as collisions require devices to abort transmission and retransmit at a later time. Collisions are often in a hub environment because each port on a hub is in the same collision domain. By contrast, each port on a bridge, a switch, or a rudder is in a separate collision domain. As you can see in here, this is collision domain one, this is collision domain three, this is collision domain two, and this is collision domain four. But as you can see in here, separate ports of the hub is not a separate collision domain. All ports of the hub are in the same collision domain, which is collision domain foreign here in a shared media, devices may want to send data at the same time. Carrier sends multiple access. CSMA method is used for sharing the media, but collisions may occur if two devices try to send data at the same time on the screen. As you can see that all workstations are saying that I send my data whenever I want and they don't want to share the media. So we have a method named CSMA CD CSMA Collision Detection used for detecting collisions for Internet networks. Logic behind this is Check media. If it is free, send. If not, wait for idle and send again later. For example, in here, if workstation A wants to communicate with the server, it sends a message saying that I need to send something. Is there anything currently on the wire or not? CSMA/CA is used for detecting collisions for wireless networks lodging behind this is check media. If it is free, send a notification to use it and then send your data. And here how is going on. For example, if this tablet wants to send data to a wireless medium, it's checking the medium, I'm sorry. First then it's sending a notification to the medium saying that hey guys, I'm going to send the data. Then it's sending whatever it's going to send. And let's take a look to the Ethernet frame. Now, in the first fields of Ethernet we have Preamble and Sft. These fields provide synchronisation between source and the destination devices. Secondly we have destination and source address fields and they are the source and destination Mac address info. And the other field is the VillainTag which is used for quality of services and carries the Villain information. That's an optional field. And the other field is Length and Type which keeps the length of data and the type of the protocol we are using. And another field is the Data field which gives the encapsulated data information from OSI layer three and the last field is SCS FrameCheck Sequence and Frame Check Sequence. Bits must match for source and destination. If not, error occurred and this field is used for the error detection. Let's take a look at the Mac address. Now a media Access Control Mac address of a device is a 48 bit unique identifier assigned to network interfaces for communications at the data link layer of a network segment, mac addresses are used as a network address for most network technologies including Ethernet and WiFi. Mac addresses are shown in Hexadecimal format. Guys, Hexadecimal is a position numeral system with a Reddicks or base of 16.It uses 16 distinct symbols. Most often these symbols from zero to nine to represent values from zero to nine as you can see in here and ABCD and ENF to represent values from ten to 15.Mac addresses are assigned to network devices such as PCs, printers, servers and etc. And consists of two portions as you can see in here. The first portion is Oui and the second is UAAA. Or extended or device. Identifier. The first portion is Oui and organizationally unique identifier. Oui is 24 bit number that uniquely identifies a vendor, manufacturer or other organization. The second portion is UAAA or extended device? Identifier. This is a number unique to the vendor. For example, let's say that this first portion is unique. For example, maybe intel, maybe quilcomb. Then the Mac addresses that intel manufacturers or Qualcomm manufacturers are finishing with the arbitrary numbers that the intel or Cougome says. Mac addresses can be represented in three ways. Mostly the first dots are used between each four characters as you can see as in here, and the second dashes are used between each two characters. Like here you can see as well and in the third double columns are used between each two characters. There are also three different types of internet addresses and they are UniQuest multi cast and the broadcast. A unicast frame contains the unique Mac address of the destination receiver and uniques address frame is only sent out the specific port leading to the receiver. For example, if this computer one wants to communicate with computer three over the switch, and if this is a unique test frame is going to do here but not here, and forward it to here. A multicast frame contains the unique multicast Macaddress of an application protocol or data stream. A multicast address frame is either fluted out all ports if no multicast optimization is configured, or sent out only the ports interested in receiving the traffic. If you want to send the multicast layer to traffic, your destination Mac should start with let's talk about the broadcast Mac address. A broadcast frame is fluted at all parts. A broadcast frame contains all binary ones as a destination rest which is FF and FF. For example, if this guy wants to communicate with all these other guys, the source address of the ethernet frame is this guy's Mac address and the destination. Let's go ahead with the ARP address resolution protocol. ARP is used for resellation of IP address into Mac address. Our prequest is made via broadcast to Ffff and Ripli is made by relay tip device as unicast. For example, if PC One sends an Art request, this message is broadcast, comes to here and comes to here. And let's say that PC One is researching the physical address of the station that has the IP address 21 Three, which is PC Three. PC Three takes this request and replies back with its Mac address and this packet is just sent to PC One as unicast. Let's take a look to the ARP table. On networking devices, a table usually called ARP Cacheor ARP table is used to maintain a correlation between each Mac address and its corresponding IP address. Art provides the protocol rules for making this correlation and providing address conversion in both directions. In here you are seeing an Art table of a router, and in here you're seeing an ARP table of a PC. The command that we are using is Show IP command to display the ARP cache of a router. And as you can see in here we are seeing the IP addresses and the Mac addresses of the same device on the table. Let's go ahead with LAN Switch. A local network switch is a networking device that connects devices together on a computer network by using packet switching to receive, process and forward data to the destination device. Switch mostly operate at layer two of the OSI module and provide switching according to Mac address. Using Mac Address table on the local area network switch, there's a table called Mac Address Table. What layer two switch is making is just switching between different ports by using Mac Address information located in the Mac Address table. Let's see how Mac address table is established on a switch. Right now the firstly the mecha rest table is empty. This is the Switch guys and Mac address table is empty. As you can see. In the first step, if PC One wants to forward a packet to PC Two, Switch floats it out of all ports and adds PC One's Mac address to its Mac address table. What is going on in here is PC One wants to communicate with PC Two? Switch checks the frame and then checks the Mac address and immediately adds the PC once Mac address to the Mac address table and saying that hey, on my first port I have a Mac address of this wants to communicate with this Mac address, but I don't have this Mac address on this table. So I'm floating the request out from all my ports. Then let's say that PC Two sends a unicast reply to PC One and switches to PC Two's Mac address to Mac address table two. Then after this process, if PC One wants to send the data to PC Two frame is forwarded directly. And in the end of the day, switch learns all of Mac addresses connected to all of its ports and establish a full Mac address table. As you can see in here and saying that on my first port I have this Mac address, on my third part I have this Mac address, on my Fort this seven this and eight this. From now on, if this PC Five wants to communicate with PC One, frame is directly forwarded to PC One. Let's go ahead with the duplex options. We have two duplex options half duplex and full duplex. Half duplex is used to describe communication where only one site can send data at time. Once one site has finished transmitting its data, the other side can respond. Only one node can send data at a time in half duplex. If both tried to send data at the same time, a collision will occur in the network. On the other hand, full duplex is used to describe communication between where both sides are able to send and receive data at the same time. In those cases, there is no danger of a collision and therefore the transfer of data is completed much faster. Let's go ahead with the auto MDX feature. In today's networks, using the proper cable type is very important guys and certain devices has a great feature to help us preventing wrong cabling auto MDIX ports. On a newer network, interfaces detect if the connection would require a crossover and automatically chooses the MDI X configuration to properly match the other end of the link. And let's take a look at the frame forwarding types. We have three frame forwarding types when we are forwarding a frame in our switch and there Storium forward, cut through and cut through fragment free. In Sterium forward method, frame is forwarded after the whole frame received and there is no CRC incatro fast forward frame is forwarded after the destination Mac address is checked and in cattle frequency frame is forwarded after 64 bytes of the frame is checked. Let's go ahead with the Poe Power over Ethernet. Now Power over Ethernet describes any systems which pass electric power along with data on twisted pair Ethernet cabling. This allows a single cable to provide both data connection and electric power to devices such as wireless access points, IP cameras and VoIP phones to provide electric over data cables to end devices and devices also must be supporting Poe technologies too. In here we are seeing a Poe switch and we have an access point, IP camera, industrial sensor and VoIP phone connected to our PU switch. If this switch is supporting Poe and also this VoIP phone sensor, IP camera and access points are supporting the Poe feature too, we don't need an extra power cable, we don't need an extra power adapter, we don't need anything else. We can provide the power of these devices by using T twisted pair copper cables. Let's take a look to the fixed and modular switch. These are the types of the switch guys fixed configuration switch are fixed in their configuration. What that means is that you cannot add features or options to the switch beyond those that originally came with the switch. The particular module you purchased that reminds the features and options available. For example, if you purchase a 24gigabit Ethernet fixed switch, you cannot add additional ports when you need them. There are typically different configuration choices that vary in how many and what types of ports are included. And let's take a look at the modular suites. Modular suites offer more flexibility in their configuration. Modular suites typically come with different sites chassis that allow for the installation of different number of modular line cards. The line cuts actually contain the ports the line card fits into the switch shafts like expansion cards fit into a PC. The larger the chassis, the more modules it can support and mostly these modular suites can carry high traffic. And let's take a look at great feature which is Stack technology. A Stackable switch is a network switch that is fully functional operating standalone but which can also be set up to operate together with one or more other network switch. With this group of switch showing the characteristics of a single switch but having the port capacity of some combined sweats. The term Stack refers to group of switches that have been set up in this way. The common characteristic of a stack acting as a single switch is that there is a single IP address for remote administration of the stack as a whole, not an IP address for the administration for each unique stack. And the last thing we are going to talk about SFB Small Form Factor Plugable the small form factor plugable is a compact hot plague optical module transceiver used for both telecommunication and data communications applications and SFP interface. This guy on networking hardware provides the device with a modular interface that the user can easily adapt to various fibre optic and copper networking standards. This is the fibre optic SFP and there are also types of this SFP which supports the copper cables as well.

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