We also do not have links that lead to sites DMCA copyright infringement. If You feel that this book is belong to you and you want to unpublish it, Please Contact us. Cisco Networking Essentials 2nd Edition. Download e-Book. Perhaps you're not an IT professional, but desire to learn network hardware maintenance and management to improve your life in aspects like security, business efficiency or for self fulfillment, but don't have a clue about where to begin?
Then keep reading, as I have the perfect solution for you to get started with networking the right way. This book is a simple, straightforward and concise beginners' guide to computer networking, and is what you've been looking for. This book recognizes that the first step to becoming a real network professional is having a solid foundation of networking essentials, and its valuable content is weaved based on that understanding.
As a beginner, I imagine that you've been having certain questions and concerns such as: What's the best way or place to start learning networking? What are some of the ess. Networking is at the heart of the digital transformation. The network is essential to many business functions today, including business critical data and operations, cybersecurity, and so much more. This is a great course for developers, data scientists, cybersecurity specialists, and other professionals looking to broaden their networking domain knowledge.
It's also an excellent launching point for students pursuing a wide range of career pathways--from cybersecurity to software development to business and more.
No prerequisites required! As the world leader of networking products and services, Cisco products are constantly growing in demand. Yet, few books are aimed at those who are beginni. SAN Storage Area Network provides systems with high-speed, lossless access to high-capacity storage devices.
Common uses of a VPN are to connect branch offices or remote users to a main office. Download it once and read it on your Kindle device, PC, phones or tablets. Instead of broadcasting to find resources, the computers check with the directory server, which results in a great reduction of traffic! The domain controller creates a group security association between the computers that are members of what is commonly called a domain or a realm in Unix.
After a user is made a member of the domain, the user will have two types of user accounts: a local account on her computer, as she had in the peer-to-peer network, and a domain account. The domain account will be created on the domain controller where it will be stored.
This domain account will allow the user to log into the domain from any computer that is a member of the domain. This simplifies the account creation process in the same way illustrated in the explanation of using a file server.
The accounts are created one time on the domain controller, and then the account will work on any computer in the domain. The domain controller, rather than the individual computers, is responsible for validating the credentials of users. Whenever a user logs into the domain from a member computer, the login request is sent to the domain controller, which verifies the name and password and then sends the user an access token.
An access token is a file that lists the resources that the user is allowed to access in the network, regardless of where the resource is located. The benefit of this security paradigm is a feature called single sign-on.
It doesn't even matter which computer the resource is on! On other hand, there are disadvantages to implementing a client-server network. The hardware and software required to deploy servers is significantly more expensive than client software found in a peer-to-peer network. Configuring and maintaining these servers also requires a much higher degree of skill. Moreover, when a single domain controller is in use, a single point of failure has been introduced to the operation of the network.
If something happens to the domain controller, such as a hardware failure, all access to resources can be interrupted. For these reasons, most networks deploy multiple domain controllers to eliminate this single point of failure, further adding to the cost of deploying a client-server network.
Consider the following scenarios and propose a design using the principles discussed in this chapter LAN, WAN, peer-to-peer, client-server. Be prepared to discuss and defend your answer. Which of the following is not an advantage of networking computers? Resource sharing B. Reduced security for data C. Potential for increased productivity D. Improved communications 2. A server is one that forms a security association between network members and helps to locate resources.
File B. Directory services C. Security controller D. Netvvork browser 3. What is the minimum number of computers required to fonn a network? Two C. Three D. Four 4. True or False: Telecommuting is when a user works from another physical location. What is a protocol? A type of transmission medium B. A security agreement C. A communications agreement D.
A suggested best practice 6. Proprietary B. Standard C. De facto D. Registered 7. Which statement is true ,;vith regard to a LAN? Distributed across a large geographical area B. High speed C. Leased from a telecommunications company D. Requires a server 8. True or False: A de facto standard is one that all parties agree to and is usually adopted by a body formed to create standards. A peer-to-peer network is also sometimes called a. Realm B. Domain C. Workgroup D. Organizational unit Which of the follovving are shortcomings of a peer-to-peer network?
Difficult to implement B. Requires server C. High cost D. Most networking solutions of the time were proprietary in nature, making it difficult to mix computer solutions from different companies. To put it in the vernacular of the time, everyone was "doing their own thing.
In this chapter, two reference models developed to address this situation are discussed. Keep in mind that these are only models, and some parts of the models evolved differently in the real world than originally envisioned.
The idea of locking customers into a system by making the system proprietary seemed like a good idea in the beginning. But it soon became apparent to the industry that if everyone got on the same page, everyone could sell more hardware and software.
What the industry needed was a vendor-neutral organization to bring order out of the chaos. The ISO has developed more than 18, international standards on a variety of subjects, and s01ne 1, new ISO standards are published every year. The ISO went about this job by creating standards. Standards are entirely voluntary in nature.
They are not laws. No vendors are required to abide by them. In some cases, some vendors chose not to follow the standard until it became apparent that the standard had been widely adopted. Most vendors saw the creation of standards as a benefit and came onboard. It's only natural that some vendors, particularly large ones, had more influence on decisions that were made than others. The ideal approach would have been to examine all proposals and select the best one on an impartial technical basis, but in reality, some industry voices were louder than others.
Cisco was and remains a large player in how networking is done. Regardless of each player's size and influence, all parties appreciated the benefits of reference models.
In this section, you'll look at some of those benefits and then explore another model before diving into the OSI model itself in the next section. Understanding the Benefits of Reference Reference models provide a common blueprint from which software and hardware developers can work.
This ultimately aids in component development at each layer by providing an assurance that the layer can be made to communicate with the layers above and below it. The goal of breaking a complicated communication process into parts, or modules which is why this process is described as modular , is to avoid the need to completely reinvent the entire communication process when a new development takes place.
By standardizing the interface between two layers interface just means the way they exchange infonnation , a change can be made on one layer without requiring a change at any other layer. As long as the standard interface between the two layers remains unchanged, the process continues to work smoothly.
All of the same functions take place in each model; in the TCPIIP model, they are just organized logically into fewer layers. Refer to this figure as the layers of the OSI model are explained and keep in mind that the process of encapsulation is the same in both models; only the number and names of the layers are different.
Introducing the Layers of the OSI Model There are seven layers in the OSI modet each layer plays a role in creating a package of data along with critical information describing the data. This package will be sent from one device to another device, where it will be taken apart and read. This process is called encapsulation and de-encapsulation and will be explained more fully in the last section of this chapter. First, the role of each layer must be understood to grasp the encapsulation process.
Let's explore each layer and its job in the process. The layers are numbered from the perspective of package reception rather than package creation. This means that the Physical layer is layer 1, and the numbers progress to layer 7, the Application layer. In this discussion, we are approaching the model from the perspective of package creation, so we will begin with discussing layer 7, the Application layer, and work our ,;vay up to layer 1, the Phy sicallayer.
However, in most Cisco docmnentation, the layer numbers of the OSI model are used for purposes of describing device and protocol mappings. For exatnple, a switch is said to be a layer 2 device, and a router a layer 3 device, rather than layers 1 and 2, respectively, as they would be if using TCPIIP layer numbers.
Understanding the Application Layer The Application layer layer 7 is where the encapsulation process begins. This is where users interface with the model by working through the service or application they are using.
The information on this layer is specific to the service or application that is requesting information to be transferred to another device. This is used to transfer web pages across the network. It could be the text of an email or a Microsoft Excel spreadsheet as well. Encryption Encryption scrambles the data so that it cannot be read if intercepted. This operation is represented in Figure The compression process eliminates redundant information so that the data takes up less space.
When the data arrives at the destination, the redundant data is added back in. This process is illustrated in Figure Figure Compression Compress Decompress If data arrives compressed, the Presentation layer ensures that it is uncompressed before it goes to the Application layer.
The reverse of both of these processes is also true. If the data is arriving from the Application layer and needs to be encrypted or compressed, the Presentation layer will take care of that. Although encryption can be done at the Presentation layer as described earlier, it can also be done at the Data-Link layer discussed later.
Where the encryption takes place affects the amount of information encrypted. If the process is done at the Presentation layer, only the data is encrypted. If done at the Data-Link layer, the entire package is encrypted. In some cases, it is desirable to "hide" some of the information about the data that is contained on the other layer.
If that were the case, the encryption should be done on the Presentation layer. This information will go "in front" of the data from the Application layer, and the resulting package will be handed down to the Session layer. When the Session layer receives this package, it will consider the entire package to be data without concerning itself with specific information added by either upper layer.
When discussing the front and back of thi s package of information, the front is the information that the destination device will receive first, and the back is what will be received last.
Understanding the Session Layer The Session layer, referred to as layer 5, is responsible for coordinating the exchanges of information between the layer 7 applications or services that are in use. In the earlier example of the web page, the Session layer would be managing the session between the browser on the source computer and the browser on the destination computer.
The Session layer starts, maintains, and ends the session between the applications. It is important to be clear that this does not mean managing the session between the computers. That occurs at a different level. This session is built and closed after the physical session between the computers has taken place. To accomplish this goal, the Session layer adds information relevant to managing the session "in front" of the information it received from the Presentation layer.
As all the layers do, it considers all the information from above as data and does not concern itself with the specific information added at layers 7 and 6.
It does this by using what are called port numbers. The port numbers have been standardized so there is no confusion. Figure illustrates how a server acting as a Telnet, FTP, and web HTTP server would use the port number assigned to Telnet, FTP, and the web service ports 23, 21 , and 80, respectively to communicate with different computers requesting different.
Computers are capable of using up to 65, ports. Port numbers 1 through 1, are called well-known ports, as they have been standardized. Port nmnbers 1, through 49, are available to be registered by software makers to use as identifiers between network endpoints of their applications. The numbers 49, through 65, are called dynamic ports and are used at random by the computers. Chapter 3 covers how those are used.
The OSI model as originally conceived was not tied to any particular set of Transport layer communication methods. Each networking protocol could have its own set of transmission processes operating at various levels of the model, including the Transport layer. As a result, port numbers come in two types, depending on the Transport layer protocol that is in use. The protocol that is used for a particular transmission depends on the type of delivery that is required.
This is not something that is a choice available to you as a user. The choice is made for you based on the type of transmission. There are three types of transmissions in a network: unicast, broadcast, and multicast.
This is also known as one-to-one. This is also known as one-to-many. Multicast When a single host is sending a transmission to some, but not all, of the hosts on the network, it is called a multicast.
This is also known as one-to-some. Figure Transmission types Unicast Wwnis. When the transmission is a unicast one-to-one , the protocol used is TCP. Those differences are discussed in Chapter 3. As all the layers do, it considers all the information from above as data and does not concern itself with the specific information added at layers 5, 6, and 7. Understanding the Network Layer The N etwork layer is responsible for identifying the destination device by its logical identification. It is based on a numbering system that makes it possible for computers and routers to identify whether the destination device is on the local network or on a remote network.
Local vs. Remote If the source and destination hosts are on the same network, the destination device is considered to be on the local network. If the two computers are on different networks, the destination device is considered to be on a remote network. What constitutes local and remote from an IP addressing standpoint is covered in Chapters 7 and 8. As all the layers do, it considers all the information from above as data and does not concern itself with the specific information added at layers 4, 5, 6, and 7.
The specific type of Data-Link identifier depends on the Data-Link protocol in use. It is applied to the network adaptor by the manufacturer during production, as shown in Figure Figure MAC addresses and network adaptors Ethernet and Ethernet is probably the technology you will most likely come in contact with because it is used in almost all LANs. MAC addresses are not the only type of layer 2 Data-Link layer addresses.
Although they look quite different from MAC addresses, they serve the same purpose. The process that is used to "learn" the MAC address is discussed in Chapter 3. As all the layers do, it considers all the information from above as data and does not concern itself with the specific information added at layers 3, 4, 5, 6, and 7.
At this point, all information added to the front of the package by layers 3- 7 will collectively be referred to as upper-layer data. And the Data-Link layer will place a header on the package called the Data-Link header.
When discussing the front and back of this package of information, the front is the information that the destination device will receive first, and the back is what will be received last. Unlike the other layers, however, the Data-Link layer will also add something to the end of the package called a trailer.
This check verifies that the data that left the source computer did not change at all during the transmission. If the data does not pass this check, the destination device will discard it because it usually indicates that the data has either been corrupted damaged in transit or has been intercepted and altered.
The main parts of the resulting package are shown in Figure All information that traverses the network is in this form, meaning it is all a series of ones and zeros that can be reconverted on the other end and read.
The physical medium must be capable of representing these ones and zeros in some form or fashion. The manner in which these bits are represented depends on the physical medium in use. If it is a wired network, the bits will be represented with the presence or absence of an electrical charge. If it is a wireless medium, the bits will be represented with radio waves that are altered or modulated so that the ones can be differentiated from the zeros.
Finally, if the cable is fiber-optic, light patterns generated by a small laser on and off will be used to indicate ones and zeros. Imagine that you are on your company website and you have clicked a link on the page. Refer to it as we take the information and identify where it goes in the process and how it is used. To simplify the process, we are going to assume that the web server is not located on the Internet, but is located on the same network as your computer.
This is not unusual, as many organizations use web servers on the local network to provide infonnation to employees. Although this example used the transfer of a web document, the process is the same for any transmission between two computers, regardless of the type of data or the protocol in use. It broke the communication process into seven layers, each describing a step in the process of data encapsulation.
The benefits of reference models, including the OSI model, is that they encourage standardization and interoperability, help enhance development on specific layers without requiring a change to other layers, and encourage hardware and software developers to build on one another's accomplishments through their modular approach.
Which of the following is not an advantage of networking reference models? They encourage standardization by defining what functions are performed at particular layers of the model. They ensure that networks perform better. They prevent changes in one layer from causing a need for changes in other lay ers, speeding development.
They encourage vendors to build on each other's developments through use of a common framework. Which organization created a four-layer reference model in the early s?
OSI B. ISO C. DoD D. Physical B. Application C. Presentation D. Session 4. Application B. Session C. Data-Link D. Physical 5. Which layer of the OSI model is responsible for coordinating the exchanges of information between the layer 7 applications or services that are in use? Physical 6. What is the information that is used on layer 3 of the OSI model?
A bit pattern B. IP addresses D. Port numbers 7. What two pieces of information are communicated in the following : TCP 23? Port number and transfer speed B. Transport protocol and encryption type C. Port number and transport protocol D. Transfer speed and encryption type 8. What are the port numbers from 1 to 1, called? Well-known B. Dynamic C. Registered D. Static 9. Which type of transmission is referred to as one-to-one?
Multicast B. Anycast C. Unicast D. Broadcast What transport protocol is used for broadcasts? TCP B. RDP C. UDP D. Over the next five years, the protocol went through four version updates. In , version 4, which we have used until just recently and are still using in combination with version 6, was presented and adopted.
When this mandate was handed down, it set in motion the adoption of TCPIIP as the protocol of the coming Internet and of any LANs that wanted to connect without using any protocol conversion to the Internet. TCPliP is not the only networking protocol ever used.
Other networking protocols were created by networking software and operating system companies to support networking between their products. Some of these protocols worked quite well, as long as all of the computers and devices were capable of using the protocol.
The problem was that companies such as Microsoft, Novell, and Apple had all gone in different directions and created their own networking protocols. There was no common language. It is now the common language of networking worldwide. Beyond this chapter, you will find that reference model mappings, whether they concern protocols or devices, will be in terms of the TCPliP model. A reference model mapping is used to link a protocol or device with the model layers that contain the information that the protocol or device acts upon.
However, in most Cisco documentation, the layer numbers of the OSI model are used for purposes of describing device and protocol mappings. For example, a switch is said to be a layer 2 device and a router a layer 3 device rather than layers 1 and 2, respectively, as they would be if using TCPIIP layer numbers. Considering the importance of this model, a brief review of the layers and a discussion of the function of each is in order. Layers use protocols. A protocol is an agreement on how something is done.
In networking, a protocol defines how the information that is transmitted from one computer to another is structured. Some protocols are special function protocols, and some are networking protocols. Networking protocols provide transport services to the special purpose protocols. They also define the rules of communication between devices. In this respect, networking protocols are like languages. The devices must share at least one common language. Although not shown in this figure, devices can also be mapped to the model.
More details M t al co dt ttY: d ora www. When a user attempts to access anything, the computer has to decide whether the object is located locally on the hard drive or is somewhere out on the network.
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