Lesson 1: Differentiate between LANs & WANs PDF

# Lesson 1: Differentiate between LANs & WANS ## 1.1 Ethernet - 1.1.1 What is Ethernet? - Ethernet is the traditional technology for connecting devices in a wired local area network (LAN) or wide area network (WAN). It enables devices to communicate with each other via a protocol, which is a...

# Lesson 1: Differentiate between LANs & WANS ## 1.1 Ethernet - 1.1.1 What is Ethernet? - Ethernet is the traditional technology for connecting devices in a wired local area network (LAN) or wide area network (WAN). It enables devices to communicate with each other via a protocol, which is a set of rules or common network language. - Ethernet describes how network devices format and transmit data so other devices on the same LAN or campus network can recognize, receive and process the information. An Ethernet cable is the physical, encased wiring over which the data travels. - Compared to wireless LAN (WLAN) technology, Ethernet is typically less vulnerable to disruptions. It can also offer a greater degree of network security and control than wireless technology because devices must connect using physical cabling. - 1.1.2Why is Ethernet used? - Ethernet initially grew popular due to its inexpensive price tag when compared to the competing technology of the time, such as IBM's token ring. As network technology advanced, Ethernet's ability to evolve and deliver higher levels of performance. - Ethernet initially ran over coaxial cables. Early Ethernet connected multiple devices into network segments through hubs - Devices responsible for transporting network data - using either a daisy chain or star topology. Currently, a typical Ethernet LAN uses special grades of twisted-pair cables or fiber optic cabling. - 1.1.3Advantages and disadvantages of Ethernet: - Ethernet has many benefits for users, which is why it grew so popular. However, there are a few disadvantages as well. - **Advantages of Ethernet**: 1. Relatively low cost. 2. Backward compatibility. 3. Resistant to noise. 4. Good data transfer quality. 5. Speed. 6. Reliability. 7. Data security, as common firewalls can be used. - **Disadvantages of Ethernet**: 1. Intended for smaller, shorter distance networks. 2. Limited mobility. 3. Use of longer cables can create crosstalk. 4. Does not work very well with real-time or interactive applications. 5. Troubleshooting is hard when trying to trace which specific cable or node is causing the issue. - 1.1.4How Ethernet works? - IEEE specifies in the family of standards called IEEE 802.3 that the Ethernet protocol touches both physical connectivity and the sent data. - Ethernet defines two units of transmission: packet and frame. The frame includes the payload of data being transmitted as well as the physical media access control (MAC) addresses of both the sender and receiver; - Like with other network types, involved computers must include a network interface card (NIC) to connect to Ethernet. ## 1.2NIC - 1.2.1 What is NIC? - A network interface card (NIC) is a hardware component without it the computer cannot be connected over a network. It is a circuit board installed in a computer that provides a dedicated network connection to the computer. It is also called network interface controller, network adapter or LAN adapter. - 1.2.2Types of NIC Cards: - NIC cards are of two types: 1. **Internal Network Cards:** - In internal networks cards, the motherboard has a slot for the network card where it can be inserted. - It requires network cables to provide network access. Internal network cards are of two types. The first type uses Peripheral Component Interconnect (PCI) connection, while the second type uses Industry Standard Architecture (ISA). 2. **External Network Cards:** - In desktops and laptops that do not have an internal NIC, external NICs are used. ## 1.3 Local area network (LAN) - The term local area network (LAN) is commonly used to describe a network of devices in a limited area (a house, office, building...). This type of network is usually capable of achieving high data transfer rate (up to 10 Gbps!) at low cost. Examples of this type of network are a small office network inside a single building or your home network. - The following figure 1.2 shows a typical LAN: - -  - One of the most popular LAN technologies is Ethernet. Most LAN networks use two common connectivity methods Ethernet and wireless networks. Wireless LANs are also known as WLANS. ## 1.4 What Is WAN? And How Wide Area Networks Function? - A wide area network (also known as WAN), is a large network of information that is not tied to a single location. WANs can facilitate communication, the sharing of information and much more between devices from around the world through a WAN provider. - WANs can be vital for international businesses, but they are also essential for everyday use, as the internet is considered the largest WAN in the world. - These networks are often established by service providers that then lease their WAN to businesses, schools, governments or the public. These customers can use the network to relay and store data or communicate with other users, no matter their location, as long as they have access to the established WAN. Access can be granted via different links, such as virtual private networks (VPNs) or lines, wireless networks, cellular networks or internet access. - As organizations grow and become international, WANs allow them to communicate between branches, share information and stay connected. When employees travel for work, WANs allow them to access the information they need so they are able to carry out their essential daily functions without delay. Employees from anywhere can use a business's WAN to share data, communicate with coworkers or simply stay connected to the greater data resource center for that organization. - WANs also help organizations share information with customers - Students at universities might rely on WANs to access library databases or university research. - And every day, people rely on WANs to communicate, bank, shop and more. ## 1.5 What's the Difference Between Wide Area Network (WAN) and Local Area Network (LAN)? - Whereas WANs can exist globally, without ties to a physical location through the use of a leased network provider, LANs exist within a limited area. LANs can be used to access a greater WAN (such as the internet), but only within the area where the LAN's infrastructure can reach. ## 1.6 What Is MAN? - The term metropolitan area network is used to describe a network in a single metropolitan area, hence the name. This type of network is usually bigger than a LAN and smaller than a WAN. An example of this type of network would be a network that connects two company offices inside the same city. # Lesson 2: Troubleshoot data communications systems - We to define some important network parameters ## 2.1 MAC & IP addresses: - **MAC address**: - A Media Access Control (MAC) address is a 48-bit (6 bytes) address that is used for communication between two hosts in an Ethernet environment. It is a hardware address, which means that it is stored in the firmware of the network card. - Every network card manufacturer gets a universally unique 3-byte code called the Organizationally Unique Identifier (OUI). Manufacturers agree to give all NICs a MAC address that begins with the assigned OUI. The manufacturer then assigns a unique value for the last 3 bytes, which ensures that every MAC address is globally unique. - MAC addresses are usually written in the form of 12 hexadecimal digits. For example, consider the following MAC address: - D8-D3-85-EB-12-E3 - Every hexadecimal character represents 4 bits, so the first six hexadecimal characters represent the vendor (Hewlett Packard in this case). - **IP address**: - An IP address is a 32-bit number that identifies a host on a network. Each device that wants to communicate with other devices on a TCP/IP network needs to have an IP address configured. For example, in order to access the Internet, your computer will need to have an IP address assigned (usually obtained by your router from the ISP). - An IP address is usually written in the form of four decimal numbers separated by periods (e.g., 10.0.50.1). The first part of the address represents the network the device is on (e.g., 10.0.0.0), while the second part of the address identifies the host device (e.g., 10.0.50.1). - In contrast to MAC address, an IP address is a logical address. It can be configured manually or it can be obtained from a DHCP server. ## 2.2troubleshooting: - 2.2.1What is Network Troubleshooting? - Network troubleshooting is the combined measures and processes used to identify, diagnose and solve problems within a computer network. It is a logical process that network engineers use to resolve network problems and improve network operations. Troubleshooting is an iterative process, the more data you collect and analyze, the higher the likelihood of developing a correct hypothesis - 2.2.2 Troubleshooting Methodology: - A troubleshooting model to effectively address network issues that will arise and equip you in handling such problems. Cisco has broken down the process into eight methodical steps: 1. Define the problem. 2. Gather detailed information. 3. Consider probable cause for the failure. 4. Devise a plan to solve the problem. 5. Implement the plan. 6. Observe the results of the implementation. 7. Repeat the process if the plan does not resolve the problem. 8. Document the changes made to solve the problem. - 2.2.3 Troubleshooting Methods: - Here are some other troubleshooting methods that can be used to efficiently isolate the root cause of the network issue and immediately implement the best solution to it. 1. **Compare Configurations:** - A lot of network performance issues are usually caused by human errors, and the initial way to troubleshoot problems is to check if there are configuration changes that have been made in the network. 2. **Trace the Path:** - One of the most used troubleshooting tools is sending a ping to your destination device. There is another ICMP-based tool that shows you where the ICMP packet stopped in the network, and that is the traceroute. 3. **Swap-out Components:** - Usually, network outages are caused by hardware failures ranging from a simple ethernet cable wear and tear to full-on equipment failure. When this happens, we have no choice but to replace the defective hardware with a new one to keep the network up and running. This approach is also used to check if there is a specific device that causes the issue in the network and monitors what happens once the swap has been made. - 2.2.4 Connectivity Troubleshooting Tools: - There are various troubleshooting tools that are being used to analyze network connection outages or performance issues. Below are some of the most effective tools that we utilize in troubleshooting and can be helpful if we understand how they function. 1. **ping**: - is a tool that is used to test the reachability of the destination host by sending an Internet Control Message Protocol (ICMP) packet towards the destination and providing the round-trip time of the packet, which shows how fast it traverses the network. 2. **Traceroute**: - is a diagnostic command that is used to identify where the ICMP packet stops if ever ping tool was not successful and did not reach the destination host. Traceroute shows where the packet travels, so it can easily help us identify where the problem lies. 3. **Telnet**: - is a protocol that provides a command-line interface for communication with a remote device or server, sometimes employed for remote management but also for initial device setup like network hardware. - 2.2.5 ICMP (Internet Control Message Protocol): - ICMP (Internet Control Message Protocol) is a network layer protocol that reports errors and provides information related to IP packet processing. ICMP is used by network devices to send error messages indicating, for example, that a requested service is not available or that a host isn't reachable. - ICMP is commonly used by network tools such as ping or traceroute. Consider the following example that illustrates how ping can be used to test the reachability of a host (figure 2.1 shows ping tool): - -  - Host A wants to test whether it can reach Server over the network. Host A will start the ping utility that will send ICMP Echo Request packets to Server. If Server is reachable, it will respond with ICMP Echo Reply packets. If Host A receives no response from Server, there might be a problem on the network. - 2.2.6 Troubleshooting examples: - **A. Solving Connectivity issues** 1. Ensure that the power supply is properly working and correctly connected. 2. Ensure that all cables are correctly connected. 3. Check the power source. 4. If you are using an Active Ethernet Power injector, ensure that the voltage is correct. - **B. Cannot use the Web Interface** 1. Open a command prompt window and enter ping <ip address unit> (for example ping 10.0.0.1). If the unit does not respond, make sure that you have the correct IP address. If the unit responds, the Ethernet connection is working properly, continue with this procedure. 2. Ensure that you are not using a proxy server for the connection with your Web browser. 3. Double-check the physical network connections. 4. Perform network infrastructure troubleshooting (check switches, routers, and so on). - **C. If Serial Link Does Not Work** - The unit cannot be reached through the serial port. 1. Check the cable connection between the unit and the computer. 2. Ensure that the correct COM port is used. 3. Ensure that the unit and the computer use the same serial port configuration parameters. 4. Disconnect and reconnect power to reset the unit. - **d. Reset to Factory Default** - What if we forget the login credentials of routers or switches and we are not able to log in to make changes in configuration? To do reset the router or switch is one of the quickest ways to resolve the issue. It will make a new and blank startup configuration file, and it will show you the setup wizard for a quick configuration of the router. - **e. General Check** - After you are able to access the network device check for any reported alarm messages in the Event Log. # Lesson 3: Network H/W devices ## 3.1 Network switch: - Switch is used to connect multiple hosts together; switch can inspect received traffic and make forwarding decisions. Each port on a switch is a separate collision domain and can run in a full duplex mode. - A switch manages the flow of data across a network by inspecting the incoming frame's destination MAC address and forwarding the frame only to the host for which the data was intended. Each switch has a dynamic table (called the MAC address table) that maps MAC addresses to ports. With this information, a switch can identify which system is sitting on which port and where to send the received frame. Fig-1.1 shows Network switch. -  ## 3.2 Network router: - A router is a network device that routes packets from one network to another. It is usually connected to two or more different networks. When a packet comes to a router port, the router reads the address information in the packet to determine out which port the packet will be sent. For example, a router provides you with the internet access by connecting your LAN with the Internet. Fig-1.2 shows Router. -  - 3.2.1 What is IP routing? - IP routing is the process of sending packets from a host on one network to another host on a different remote network. This process is usually done by routers. Routers examine the destination IP address of a packet, determine the next-hop address, and forward the packet. Routers use routing tables to determine the next hop address to which the packet should be forwarded. - Consider the following example in figure 3.3 of IP routing: -  - Host A wants to communicate with host B, but host B is on another network. Host A is configured to send all packets destined for remote networks to router R1. Router R1 receives the packets, examines the destination IP address and forwards the packet to the outgoing interface associated with the destination network. - 3.2.2 Default gateway: - A default gateway is a router that hosts use to communicate with other hosts on remote networks. A default gateway is used when a host doesn't have a route entry for the specific remote network and doesn't know how to reach that network. Hosts can be configured to send all packets destined to remote networks to the default gateway, which has a route to reach that network. - The following example in figure 3.4 explains the concept of a default gateway more thoroughly. -  - Host A has an IP address of the router R1 configured as the default gateway address. Host A is trying to communicate with host B, a host on another, remote network. Host A looks up in its routing table to check if there is an entry for that destination network. If the entry is not found, the host sends all data to the router R1. Router R1 receives the packets and forwards them to host B. ## 3.3 Gateway: - Gateways are basically protocol converters, facilitating compatibility between two protocols. - 3.3.1 How gateways work? - All networks have a boundary that limits communication to devices that are directly connected to it. Due to this, if a network wants to communicate with devices, nodes or networks outside of that boundary, they require the functionality of a gateway. A gateway is often characterized as being the combination of a router and a modem. - The gateway is implemented at the edge of a network and manages all data that is directed internally or externally from that network. When one network wants to communicate with another, the data packet is passed to the gateway and then routed to the destination through the most efficient path. In addition to routing data, a gateway will also store information about the host network's internal paths and the paths of any additional networks that are encountered. - One use for gateways is creating a communication link between an IoT environment and the cloud as shown in Figure 3.5. -  - 3.3.2 Types of gateways: - Gateways can take several forms and perform a variety of tasks. Examples of this include: 1. **Web application firewalls**- This type filters traffic to and from a web server and looks at application-layer data. 2. **Cloud storage gateways**- This type translates storage requests with various cloud storage service API calls. It allows organizations to integrate storage from a private cloud into applications without migrating into a public cloud. 3. **API, SOA or XML gateways** – This type manages traffic flowing into and out of a service, microservices-oriented architecture or XML-based web service. 4. **IoT gateways**-This type aggregates sensor data from devices in an IoT environment, translates between sensor protocols and processes sensor data before sending it onward. 5. **Media gateways**- This type converts data from the format required for one type of network to the format required for another. 6. **Email security gateways**- This type prevents the transmission of emails that break company policy or will transfer information with malicious intent. 7. **VoIP trunk gateways**- This type facilitates the use of plain old telephone service equipment, such as landline phones and fax machines, with a voice over IP (VoIP) network. ## 3.4 servers: - 3.4.1 What is a Server? - A server is a computer program or device that provides a service to another computer program and its user, also known as the client. In a data center, the physical computer that a server program runs on is also frequently referred to as a server. That machine might be a dedicated server or it might be used for other purposes. - A given application in a computer might function as a client with requests for services from other programs and as a server of requests from other programs. - 3.4.2 How servers work? - The term server can refer to a physical machine, a virtual machine or to software that is performing server services. The way that a server works varies considerably depending on how the word server is being used. ## 3.4.3 Physical and virtual servers: - A physical server is simply a computer that is used to run server software. The differences between a server and a desktop computer will be discussed in - A virtual server is a virtual representation of a physical server. Like a physical server, a virtual server includes its own operating system and applications. These are kept separate from any other virtual servers that might be running on the physical server. - The process of creating virtual machines involves installing a lightweight software component called a hypervisor onto a physical server. The hypervisor's job is to enable the physical server to function as a virtualization host. The virtualization host makes the physical server's hardware resources such as CPU time, memory, storage and network bandwidth -- available to one or more virtual machines. - An administrative console gives administrators the ability to allocate specific hardware resources to each virtual server. This helps dramatically drive down hardware costs because a single physical server can run multiple virtual servers, as opposed to each workload needing its own physical server. ## 3.4.4 Desktop computers vs. servers: -  - **Desktop computers vs. servers** | POC | Desktop computer | Servers | |-------------|----------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | CPU | • X86/X64 CPU Architecture | • X86/X64 CPU Architecture physical servers often include multiple CPU sockets and error correcting memory | | Quantity of Memory | • Less quantity of memory than servers | • greater quantity of memory | | Operating System | • Windows <br> • Linux | • Windows Server | | Hardware | • form factor : Modern desktop computers often exist as mini towers, designed to be placed under a desk | • form factor: most servers are designed to be rack mounted. These rack mount systems are described as having a 1U, 2U or 4U form factor, depending on how much rack space they occupy - a 2U server takes up twice as much rack space as a 1U server <br> • Because server hardware typically runs mission-critical workloads, server hardware manufacturers design servers to support redundant components. <br> • A server might be equipped with redundant power supplies and redundant network interfaces. These redundant components allow a server to continue to function even if a key component fails. |