This Document Contains Chapters 1 to 3 Chapter 1 An Introduction to Networking At a Glance Instructor’s Manual Table of Contents •Overview •Objectives •Teaching Tips •Quick Quizzes •Class Discussion Topics •Additional Projects •Additional Resources •Key Terms Lecture Notes Overview Loosely defined, a network is a group of computers and other devices connected by some type of transmission media. Variations on the elements of a network and its design, however, are nearly infinite. Additionally, the size of a network may be small or large. Network communication media includes copper wires, fiber-optic cable, radio waves, infrared, or satellite links. This chapter introduces the student to the fundamental characteristics of networks. Chapter Objectives After reading this chapter and completing the exercises, the student will be able to: •List the advantages of networked computing relative to stand-alone computing •Distinguish between client/server and peer-to-peer networks •List elements common to all client/server networks •Describe several specific uses for a network •Identify some of the certifications available to networking professionals •Identify the kinds of skills and specializations that will help you excel as a networking professional Teaching Tips Why Use Networks? 1. Define a network. 2. Define a stand-alone computer. 3. Describe the advantages of using networks relative to stand-alone computers. Types of Networks 1. Explain the general factors differentiating network models. 2. Introduce the peer-to-peer and client/server network models. Peer-to-Peer Networks 1. Discuss the characteristics of a peer-to-peer network. 2. Describe the characteristics of a traditional peer-to-peer network. 3. Use Figure 1-1 to illustrate resource sharing on a peer-to-peer network. 4. Describe the advantages of peer-to-peer networks. 5. Describe the disadvantages of peer-to-peer networks. 6. Explain how resources are shared on a peer-to-peer network. Teaching Tip Be sure to emphasize that modifying file-sharing controls is operating system dependent and that this method of resource sharing may lead to access controls that are not uniform or secure. 7. Describe the environments in which peer-to-peer networks are implemented. Client/Server Networks 1. Introduce the client/server model. 2. Define a server emphasizing its client/server role. 3. Define a client. Teaching Tip Be sure to emphasize the difference between the term client/server network and the term client/server architecture. 4. Explain the two roles a computer may assume in a client/server network. Teaching Tip Be sure to emphasize that it is possible for a computer to act as both a client and a server and explain how this might occur. 5. Describe how clients and servers communicate. 6. Use Figure 1-2 to illustrate and explain resource sharing on a client/server network. 7. Describe a server’s operating system requirement. 8. Provide examples of current Network Operating Systems. 9. Explain the features of servers relative to clients. 10. Describe the disadvantage of a client/server network relative to a peer-to-peer network. 11. Describe the advantages of a client/server network relative to a peer-to-peer network. LANs, MANs, and WANs 1. Define and describe a LAN. 2. Use Figure 1-3 to illustrate a more complex client/server network. 3. Define and describe a MAN. 4. Define and describe a WAN. 5. Use Figure 1-4 to illustrate a more complex client/server network. Teaching Tip Be sure to mention that most MANs can also be described as WANs. Elements Common to Client/Server Networks 1. Describe the basic elements common to client/server networks. a. Client b. Server c. Workstation d. NIC (network interface card) e. NOS (network operating system f. Host g. Node h. Connectivity device i. Segment j. Backbone k. Topology l. Protocol m. Data packets n. Transmission o. Addressing scheme 2. Use Figure 1-5 to illustrate a NIC. 3. Use Figure 1-6 to illustrate a LAN backbone. 4. Use Figure 1-7 to illustrate common network topologies. 5. Use Figure 1-8 to illustrate examples of network transmission media. Quick Quiz 1 1. True or False: Before networks, transferring data via floppy disks was the only possible way to share data. Answer: True 2. True or False: A client/server network is the simplest network model. Answer: False 3. True or False: A common way to share resources on a client/server network is by modifying the file-sharing controls via the computer’s operating system. Answer: False 4. A network that is larger than a LAN and connects clients and servers from multiple buildings is known as a(n) ____. Answer: MAN (metropolitan area network) 5. Which term identifies a computer that enables resource sharing by other computers on the same network? a. Subnode b. Host c. Node d. NIC Answer: B How Networks Are Used 1. Define network services. 2. Identify and discuss the most visible network service - E-mail. 3. Mention other vital services. File and Print Services 1. Define file services. 2. Define a file server. 3. Discuss why file services are the foundation of networking today. 4. Define print services and describe the advantages the service provides. Access Services 1. Describe the two functions of access services. 2. Define a remote user. 3. Explain how network operating systems implement access services. 4. Describe the circumstances where access services are most often implemented by organizations. 5. Emphasize how remote access servers allow external users to use network resources and devices just as if they were logged on to a workstation in the office. Communications Services 1. Define convergence. 2. Define unified communications. 3. Identify and explain the oldest and still most frequently used network communications services. 4. Describe the additional tasks mail servers handle. 5. Describe and identity additional software mail servers need to run. Internet Services 1. Describe the Web service function. 2. Define a Web server. 3. Mention other Internet services. Teaching Tip Students may find more information of Microsoft’s Windows® Web Server 2008 at http://www.microsoft.com/en-us/server-cloud/windows-server/internet-information-services-iis.aspx Management Services 1. Define and describe network management services. 2. Explain other important network management services. a. Traffic monitoring and control b. Load balancing c. Hardware diagnosis and failure alert d. Asset management e. License tracking f. Security auditing g. Software distribution h. Address management i. Backup and restoration of data Becoming a Networking Professional 1. Describe the general atmosphere regarding networking jobs. 2. Explain the general steps to enter the networking job market successfully. Teaching Tip Demonstrate a live search of networking jobs using various related keywords on http://www.monster.com to illustrate the vast number of networking positions available. Mastering the Technical Challenges 1. Review the skill sets desired for networking positions utilizing logical and analytical thinking. 2. Describe the networking specialties currently in high demand. 3. Describe the various learning methods available and emphasize the importance of determine personal learning preferences. 4. Emphasize the importance of obtaining hands-on experience when it comes to improving networking hardware and software skills. Developing Your “Soft Skills” 1. Define and describe soft skills. Be sure to explain how they are advantageous in networking projects. Pursuing Certification 1. Define the certification process. 2. Provide an example of a professional organization offering certifications. 3. Provide examples of vendor organizations offering certifications. 4. Discuss the benefits of network certification. 5. Describe the drawback of certifications. Finding a Job in Networking 1. Describe the various resources and methods a student can use to find a job in networking: a. Search the Web b. Check your local newspaper’s Web site c. Visit a career center d. Network e. Attend career fairs f. Enlist a recruiter Joining Professional Associations 1. Explain the varying benefits of joining professional associations. 2. Use Table 1-1 to illustrate prominent professional organizations. Quick Quiz 2 1. The functions provided by a network are usually referred to as network ____. Answer: services 2. A(n) ____ server may also be known as simply an access server. Answer: remote access 3. True or False: The oldest and still most frequently used network communications services are print services. Answer: False 4. True or False: Configuration and optimization of routers and switches is a skill currently in high demand. Answer: True 5. The term ____ refers to those skills that are not easily measurable. Answer: soft skills Class Discussion Topics 1. Discuss the differences and similarities between a peer-to peer network and a client server network. 2. Have students express how they would prefer to go about finding a networking position and explain why they feel it would work best for them. Additional Projects 1. Have students research employment possibilities in the networking area by reviewing networking job postings online and in print. The student should write a case report for ten job postings. The report should include the following sections for each job posting: organization name; job title; country/state; educational requirements; hands-on experience requirements; certification requirements; contract type (part-time, full-time, contract); salary range; and benefits. Additional Resources 1. Network World IT Careers http://www.networkworld.com/topics/it-careers/index.html 2. The Northern Virginia Technology Council (NVTC) http://www.nvtc.org 3. Certification Magazine http://www.certmag.com 4. How Stuff Works – Networking Library http://computer.howstuffworks.com/computer-networking-channel.htm Key Terms A+ The professional certification established by CompTIA that verifies knowledge about PC operation, repair, and management. access server See remote access server. address A number that uniquely identifies each workstation and device on a network. Without unique addresses, computers on the network could not reliably communicate. address management The process of centrally administering a finite number of network addresses for an entire LAN. Usually this task can be accomplished without touching the client workstations. addressing The scheme for assigning a unique identifying number to every workstation and device on the network. The type of addressing used on a network depends on its protocols and network operating system. asset management The process of collecting and storing data on the number and types of software and hardware assets in an organization’s network. The data collection is automated by electronically examining each network client from a server. backbone The part of a network to which segments and significant shared devices (such as routers, switches, and servers) connect. A backbone is sometimes referred to as “a network of networks” because of its role in interconnecting smaller parts of a LAN or WAN. backing up The process of copying critical data files to a secure storage area. Often, backups are performed according to a formulaic schedule. CCIE (Cisco Certified Internetwork Expert) An elite certification that recognizes expert-level installation, configuration, management, and troubleshooting skills on networks that use a range of Cisco Systems’ devices. CCNA (Cisco Certified Network Associate) A professional certification that attests to one’s skills in installing, configuring, maintaining, and troubleshooting medium-sized networks that use Cisco Systems’ switches and routers. certification The process of mastering material pertaining to a particular hardware system, operating system, programming language, or other software program, then proving your mastery by passing a series of exams. Cisco Certified Internetwork Expert See CCIE. Cisco Certified Network Associate See CCNA. client A computer on the network that requests resources or services from another computer on a network. In some cases, a client could also act as a server. The term client may also refer to the user of a client workstation or a client software application installed on the workstation. client/server architecture A network design in which client computers use a centrally administered server to share data, data storage space, and devices. client/server network A network that uses centrally administered computers, known as servers, to enable resource sharing for and to facilitate communication between the other computers on the network. CompTIA (Computing Technology Industry Association) An association of computer resellers, manufacturers, and training companies that sets industry-wide standards for computer professionals. CompTIA established and sponsors the A+ and Network+ (Net+) certifications. Computing Technology Industry Association See CompTIA. connectivity device One of several types of specialized devices that allows two or more networks or multiple parts of one network to connect and exchange data. convergence The use of data networks to carry voice (or telephone), video, and other communications services in addition to data. file server A specialized server that enables clients to share applications and data across the network. file services The functions of a file server that allow users to share data files, applications, and storage areas. host A computer that enables resource sharing by other computers on the same network. Internet A complex WAN that connects LANs and clients around the globe. Internet services The services that enable a network to communicate with the Internet, including Web servers and browsers, file transfer capabilities, Internet addressing schemes, security filters, and a means for directly logging on to other computers. LAN (local area network) A network of computers and other devices that is confined to a relatively small space, such as one building or even one office. license tracking The process of determining the number of copies of a single application that are currently in use on the network and whether the number in use exceeds the authorized number of licenses. load balancing The process of distributing data transfer activity evenly so that no single device is overwhelmed. local area network See LAN. mail server A server that manages the storage and transfer of e-mail messages. mail services The network services that manage the storage and transfer of e-mail between users on a network. In addition to sending, receiving, and storing mail, mail services can include filtering, routing, notification, scheduling, and data exchange with other mail servers. MAN (metropolitan area network) A network that is larger than a LAN, typically connecting clients and servers from multiple buildings, but within a limited geographic area. For example, a MAN could connect multiple city government buildings around a city’s center. management services The network services that centrally administer and simplify complicated management tasks on the network. Examples of management services include license tracking, security auditing, asset management, address management, software distribution, traffic monitoring, load balancing, and hardware diagnosis. MCITP (Microsoft Certified IT Professional) A professional certification established by Microsoft that demonstrates in-depth knowledge about Microsoft products. metropolitan area network See MAN. Microsoft Certified IT Professional See MCITP. motherboard The main circuit board that controls a computer. network A group of computers and other devices (such as printers) that are connected by and can exchange data via some type of transmission media, such as a cable, a wire, or the atmosphere. network adapter See NIC. Network+ (Net+) The professional certification established by CompTIA that verifies broad, vendor-independent networking technology skills, such as an understanding of protocols, topologies, networking hardware, and network troubleshooting. network interface card See NIC. network operating system See NOS. network services The functions provided by a network. NIC (network interface card) The device that enables a workstation to connect to the network and communicate with other computers. NICs are manufactured by several different companies and come with a variety of specifications that are tailored to the workstation’s and the network’s requirements. NICs are also called network adapters. node A computer or other device connected to a network, which has a unique address and is capable of sending or receiving data. NOS (network operating system) The software that runs on a server and enables the server to manage data, users, groups, security, applications, and other networking functions. The most popular network operating systems are UNIX, Linux, and Microsoft Windows Server 2008 R2. P2P network See peer-to-peer network. packet A discrete unit of information sent from one node on a network to another. peer-to-peer network A network in which every computer can communicate directly with every other computer. By default, no computer on a peer-to-peer network has more authority than another. However, each computer can be configured to share only some of its resources and keep other resources inaccessible to other nodes on the network. print services The network service that allows printers to be shared by several users on a network. protocol A standard method or format for communication between network devices. For example, some protocols ensure that data are transferred in sequence and without error from one node on the network to another. Other protocols ensure that data belonging to a Web page are formatted to appear correctly in a Web browser window. Still others encode passwords and keep data transmissions secure. remote access server A server that runs communications services that enable remote users to log on to a network. Also known as an access server. remote user A person working on a computer on a different network or in a different geographical location from the LAN’s server. resources The devices, data, and data storage space provided by a computer, whether stand-alone or shared. restoring The process of retrieving files from a backup. It is necessary to restore files if the original files are lost or deleted. scalable The property of a network that allows you to add nodes or increase its size easily. security auditing The process of evaluating security measures currently in place on a network and notifying the network administrator if a security breach occurs. segment A part of a network. Usually, a segment is composed of a group of nodes that share the same communications channel for all their traffic. server A computer on the network that manages shared resources. Servers usually have more processing power, memory, and hard disk space than clients. They run network operating software that can manage not only data, but also users, groups, security, and applications on the network. sneakernet A way of exchanging data between computers that are not connected on a network. The term “sneakernet” was coined before the widespread use of networks, when data was copied from a computer to a removable storage device such as a floppy disk, carried (presumably by someone wearing sneakers) to another computer, then copied from the storage device onto the second computer. soft skills The skills such as customer relations, oral and written communications, dependability, teamwork, and leadership abilities, which are not easily measured, but are nevertheless important in a networking career. software distribution The process of automatically transferring a data file or installing a software application from the server to a client on the network. spam Unsolicited, unwanted e-mail. stand-alone computer A computer that uses applications and data only from its local disks and that is not connected to a network. topology The physical layout of computers on a network. traffic The data transmission and processing activity taking place on a computer network at any given time. traffic monitoring The process of determining how much data transfer activity is taking place on a network or network segment and notifying administrators when a segment becomes overloaded. transmission media The means through which data are transmitted and received. Transmission media may be physical, such as wire or cable, or wireless, such as radio waves. unified communications The centralized management of multiple types of network-based communications, such as voice, video, fax, and messaging services. user A person who uses a computer. WAN (wide area network) A network that spans a long distance and connects two or more LANs. Web server A computer that manages Web site services, such as supplying a Web page to multiple users on demand. wide area network See WAN. workstation A computer that runs a desktop operating system and connects to a network. Chapter 2 Networking Standards and the OSI Model At a Glance Instructor’s Manual Table of Contents •Overview •Objectives •Teaching Tips •Quick Quizzes •Class Discussion Topics •Additional Projects •Additional Resources •Key Terms Lecture Notes Overview In the field of networking, even though the communication that occurs between two nodes on a network cannot be seen, a model may be used to depict how the communication takes place. The model commonly used to describe network communications is called the OSI (Open Systems Interconnection) model. In this chapter, the student will learn about the standards organizations that have helped create the various conventions (such as the OSI model) used in networking. Next, the student will be introduced to the seven layers of the OSI model and learn how they interact. The student will then take a closer look at what goes on in each layer. Finally, the student will learn to apply those details to a practical networking environment. Thoroughly understanding the OSI model is essential to proficient network design and troubleshooting. Chapter Objectives After reading this chapter and completing the exercises, the student will be able to: •Identify organizations that set standards for networking •Describe the purpose of the OSI model and each of its layers •Explain specific functions belonging to each OSI model layer •Understand how two network nodes communicate through the OSI model •Discuss the structure and purpose of data packets and frames •Describe the two types of addressing covered by the OSI model Teaching Tips Networking Standards Organizations 1. Define a standard. 2. Explain why standards are important in the world of networking. 3. Emphasize that standards define the minimum acceptable performance of a product or service - not the ideal. 4. Explain why there are many different organizations to oversee computer industry standards. 5. Using ANSI and IEEE as an example, point out that standards organizations may overlap in their responsibilities. 6. Note the importance of being familiar with the groups that set networking standards and the critical aspects of standards required by a student’s network. ANSI 1. Describe the ANSI (American National Standards Institute) organization. 2. Point out that ANSI does not dictate that manufacturers comply with its standards, but requests voluntarily compliance. 3. Note that new electronic equipment and methods must undergo rigorous testing to prove they are worthy of ANSI’s approval. 4. Mention that ANSI standards documents are available for purchase online from ANSI’s Web site (www.ansi.org). Teaching Tip Go to the ANSI website at http://www.ansi.org to provide a demonstration of the ANSI material available online. EIA and TIA 1. Describe the EIA (Electronic Industries Alliance) trade organization. 2. Explain how the TIA (Telecommunications Industry Association) subgroup was formed and describe its relation to EIA. 3. Identify the best-known standard to come from EIA/TIA (TIA/EIA 568-B Series). Teaching Tip Go to the EIA website at http://www.eia.org and provide an example of the EIA material available online. Teaching Tip Go to the TIA website at http://www.tiaonline.org and provide an example of the TIA material available online. IEEE 1. Describe the IEEE (Institute of Electrical and Electronics Engineers). 2. Explain the goal of IEEE. 3. Mention that IEEE technical papers and standards are highly respected in the networking profession. Teaching Tip Go to the IEEE website at http://www.ieee.org and provide an example of the IEEE material available online. ISO 1. Describe the ISO (International Organization for Standardization). 2. Explain the goal of ISO. 3. Describe the realm of ISO’s authority. Teaching Tip Go to the ISO website at http://www.iso.org and provide a demonstration of the ISO material available online. ITU 1. Describe the ITU (International Telecommunication Union). 2. Describe the history of the ITU. 3. Explain the focus areas of the ITU. Teaching Tip Go to the ITU website at http://www.itu.int and provide an example of the ITU material available online. ISOC 1. Describe the ISOC (Internet Society). 2. Explain current ISOC concerns. 3. Describe two groups the ISOC oversees: a. IAB (Internet Architecture Board) b. IETF (Internet Engineering Task Force) 4. Describe the general process for submitting a standard proposal to the ISOC. Teaching Tip Go to the ISOC website at http://www.isoc.org and provide an example of ISOC material available online. IANA and ICANN 1. Explain why it is important for every computer on a network (including the Internet) to have a unique address. 2. Describe an IP (Internet Protocol) address. 3. Explain how every Internet-connected device is given a unique IP address. 4. Explain the history of IP address distribution. 5. Explain how an individual or business obtains IP addresses. Teaching Tip Go to the IANA website at http://www.iana.org and provide an example of the IANA material available online. Teaching Tip Go to the ICANN website at http://www.icann.org and provide an example of the ICANN material available online. Quick Quiz 1 1. True or False: Standards define maximum acceptable performance. Answer: False 2. True or False: Standards help to ensure interoperability between software and hardware from different manufacturers. Answer: True 3. Which standards organization requests voluntary compliance with their standards? a) IANA b) ISO c) ITU d) ANSI Answer: D 4. Which standards organization’s technical papers and standards are highly respected in the networking profession? a) ICANN b) ANSI c) IEEE d) ISO Answer: C 5. Which standards organization is a professional membership society that helps to establish technical standards for the Internet? a) ISOC b) ANSI c) IEEE d) ISO Answer: A The OSI Model 1. Define and describe the OSI model. 2. Introduce the seven layers of the OSI model. 3. Review the definition of a protocol. 4. Explain how the services at each layer use protocols. 5. Emphasize that the OSI model is a theoretical representation of what happens between two nodes communicating on a network. 6. Describe a PDU (protocol data units) and explain how it flows through the model. 7. Use Figure 2-1 to illustrate the flow of data through the OSI model. Teaching Tip Students may find more information on the OSI Model's seven layers at http://support.microsoft.com/kb/103884 Application Layer 1. Introduce and describe the Application layer. 2. Explain how the Application Layer facilitates communication between software applications and lower-layer network services. 3. Explain how software applications negotiate their formatting, procedural, security, synchronization, and other requirements with the network. Presentation Layer 1. Introduce and describe the function of the protocols in the Presentation layer. 2. Note that the Presentation layer protocols also interpret coded and compressed formats in data received from other computers. 3. Explain how the Presentation layer services also manage data encryption (such as the scrambling of passwords) and decryption. Session Layer 1. Introduce and describe the function of the protocols in the Session layer. 2. Define the term session. 3. Describe the functions of the Session layer. 4. Explain how the Session layer protocols keep connections alive for the duration of a session. Transport Layer 1. Introduce and describe the function of the protocols in the Transport layer. 2. Define and describe connection-oriented protocols. 3. Define and describe a checksum. 4. Define and describe connectionless protocols. 5. Define and describe segmentation. 6. Define and describe MTU (maximum transmission unit). 7. Explain how Transport layer protocols determine a network’s MTU. 8. Define and discuss reassembly. 9. Define and discuss sequencing. 10. Use Figure 2-5 to illustrate the concept of segmentation and reassembly. 11. Use Figure 2-6 to illustrate the information contained in an actual TCP segment used to request the Web page www.loc.gov/index.html. Network Layer 1. Introduce and describe the function of the protocols in the Network layer. 2. Define and discuss addressing. 3. Explain the two types of node addresses: a. Network address b. Physical address 4. Explain how the data unit accepted from the Transport layer is transformed into a packet. 5. Explain routing. 6. Define a router. 7. Note that the IP protocol is the most common Network layer protocol. 8. Use Figure 2-7 to illustrate an IP packet. 9. Define and discuss fragmentation. Data Link Layer 1. Introduce and describe the function of the protocols in the Data Link layer. 2. Define a frame and explain its purpose. 3. Explain the function of the Data Link layer using an analogy where computers communicate as humans do. 4. Describe the communication mishap referred to as partial communication. 5. Explain how partial communication is addressed using error checking and CRC (cyclic redundancy check). 6. Describe the possible communication mishap referred to as a glut of communication. 7. Explain how the glut of communication mishap is controlled by allowing the data link layer to control the flow of information, allowing the NIC to process data without error. 8. Define and describe the two Data Link layer sublayers: a. LLC (Logical Link Control) sublayer b. MAC (Media Access Control) sublayer 9. Describe where a student may find a NIC’s MAC address. 10. Use Figure 2-9 to illustrate a NIC’s MAC address. 11. Describe the two components of a MAC address: a. Block ID b. Device ID 12. Explain how the components obtain numeric values. 13. Emphasize the combination of the block ID and device ID result in a unique, 12-character MAC address. 14. Mention the newer EUI-64 standard for physical addresses. 15. Note the use of hexadecimal notation to represent the MAC address. 16. Explain how a student can determine which company manufactured a NIC by looking up its block ID if you know a computer’s MAC address. Physical Layer 1. Introduce and describe the function of the protocols in the Physical layer. 2. Explain the different signal types corresponding to the different transmission media. 3. Explain the process that occurs when the Physical layer protocols receive data. 4. Note that Physical layer protocols cannot perform error checking. 5. Describe the devices operating at the Physical layer. 6. Explain the OSI layers where a NIC may operate. Applying the OSI Model 1. Use Table 2-1 to review the functions of the OSI layers. Communication Between Two Systems 1. Remind students how the original data issued by the software applications is significantly transformed as it passes from the Application layer to the Physical layer. 2. Use Figure 2-11 to illustrate data transformation through the OSI model. Focus on the header data added at each layer. Frame Specifications 1. Review the definition of a frame. 2. Mention that the characteristics of frame components depend on the type of network on which the frames run and on the standards that they must follow. 3. Introduce the Ethernet network and discuss Ethernet frames. 4. Introduce the Token Ring network. 5. Discuss how Ethernet frames and Token Ring frames differ. IEEE Networking Specifications 1. Introduce and describe the IEEE Project 802. 2. Describe the networking specifications covered under IEEE’s Project 802. 3. Use Table 2-2 to illustrate IEEE 802 specifications. Quick Quiz 2 1. Which standards organization is responsible for providing the OSI model? a) ISOC b) ANSI c) IEEE d) ISO Answer: D 2. The seventh layer of the OSI model is the ____ layer. Answer: Application 3. The Application layer separates data into ____, or discrete amounts of data. Answer: PDUs (protocol data units) 4. Protocols in the ____layer accept data from the Session layer and manage end-to-end delivery of data. Answer: Transport 5. True or False: The IP (Internet Protocol) operates in the Transport layer. Answer: False Class Discussion Topics 1. Discuss whether the OSI model is “out of date” for today’s modern networks. 2. Discuss whether there are too many standards organizations attempting to regulate the networking field. Ask students to consider whether consultation is necessary, and whether governmental or larger international bodies should be formed to manage standards. Additional Projects 1. The student has learned that the OSI model allows TCP to function at the Transportation layer and IP to function at the Network layer. Have the students’ research TCP/IP protocols functions in more depth in relation to the OSI model. The students should then prepare a report summarizing their research. Included in the report should be a critique of the question, “Does the OSI models conform to the TCP/IP protocols, or vice versa? Require students to defend their thoughts. 2. Have the students research IEEE Project 802 and prepare a report of their research. Additional Resources 1. OSI Model http://en.wikipedia.org/wiki/OSI_model 2. OSI 7 Layers Reference Model For Network Communication http://www.javvin.com/osimodel.html 3. CompTIA Site http://www.comptia.org/ 4. ISO site http://www.iso.org Key Terms 802.2 The IEEE standard for error and flow control in data frames. 802.3 The IEEE standard for Ethernet networking devices and data handling (using the CSMA/CD access method). 802.5 The IEEE standard for token ring networking devices and data handling. 802.11 The IEEE standard for wireless networking. ACK (acknowledgment) A response generated at the Transport layer of the OSI model that confirms to a sender that its frame was received. The ACK packet is the third of three in the three-step process of establishing a connection. acknowledgment See ACK. American National Standards Institute See ANSI. ANSI (American National Standards Institute) An organization composed of more than 1000 representatives from industry and government who together determine standards for the electronics industry in addition to other fields, such as chemical and nuclear engineering, health and safety, and construction. API (application programming interface) A set of routines that make up part of a software application. Application layer The seventh layer of the OSI model. Application layer protocols enable software programs to negotiate formatting, procedural, security, synchronization, and other requirements with the network. application programming interface See API. block ID See OUI. checksum A method of error checking that determines if the contents of an arriving data unit match the contents of the data unit sent by the source. company id See OUI. connection oriented A type of Transport layer protocol that requires the establishment of a connection between communicating nodes before it will transmit data. connectionless A type of Transport layer protocol that services a request without requiring a verified session and without guaranteeing delivery of data. CRC (cyclic redundancy check) An algorithm (or mathematical routine) used to verify the accuracy of data contained in a data frame. cyclic redundancy check See CRC. Data Link layer The second layer in the OSI model. The Data Link layer bridges the networking media with the Network layer. Its primary function is to divide the data it receives from the Network layer into frames that can then be transmitted by the Physical layer. Data Link layer address See MAC address. device ID See extension identifier. EIA (Electronic Industries Alliance) A trade organization composed of representatives from electronics manufacturing firms across the United States that sets standards for electronic equipment and lobbies for legislation favorable to the growth of the computer and electronics industries. Electronic Industries Alliance See EIA. encapsulate The process of wrapping one layer’s PDU with protocol information so that it can be interpreted by a lower layer. For example, Data Link layer protocols encapsulate Network layer packets in frames. Ethernet A networking technology originally developed at Xerox in the 1970s and improved by Digital Equipment Corporation, Intel, and Xerox. Ethernet, which is the most common form of network transmission technology, follows the IEEE 802.3 standard. EUI-64 (Extended Unique Identifier-64) The IEEE standard defining 64-bit physical addresses. In the EUI-64 scheme, the OUI portion of an address is 24 bits in length. A 40-bit extension identifier makes up the rest of the physical address to total 64 bits. Extended Unique Identifier-64 See EUI-64. extension identifier A unique set of characters assigned to each NIC by its manufacturer. In the traditional, 48-bit physical addressing scheme, the extension identifier is 24 bits long. In EUI-64, the extension identifier is 40 bits long. FCS (frame check sequence) The field in a frame responsible for ensuring that data carried by the frame arrives intact. It uses an algorithm, such as CRC, to accomplish this verification. flow control A method of gauging the appropriate rate of data transmission based on how fast the recipient can accept data. fragmentation A Network layer service that subdivides segments it receives from the Transport layer into smaller packets. frame A package for data that includes not only the raw data, or “payload,” but also the sender’s and recipient’s addressing and control information. Frames are generated at the Data Link layer of the OSI model and are issued to the network at the Physical layer. frame check sequence See FCS. hardware address See MAC address. HTTP (Hypertext Transfer Protocol) An Application layer protocol that formulates and interprets requests between Web clients and servers. Hypertext Transfer Protocol See HTTP. IAB (Internet Architecture Board) A technical advisory group of researchers and technical professionals responsible for Internet growth and management strategy, resolution of technical disputes, and standards oversight. IANA (Internet Assigned Numbers Authority) A nonprofit, United States government-funded group that was established at the University of Southern California and charged with managing IP address allocation and the Domain Name System. The oversight for many of IANA’s functions was given to ICANN in 1998; however, IANA continues to perform Internet addressing and Domain Name System administration. ICANN (Internet Corporation for Assigned Names and Numbers) The non-profit corporation currently designated by the United States government to maintain and assign IP addresses. IEEE (Institute of Electrical and Electronics Engineers) An international society composed of engineering professionals. Its goals are to promote development and education in the electrical engineering and computer science fields. IETF (Internet Engineering Task Force) An organization that sets standards for how systems communicate over the Internet (for example, how protocols operate and interact). Institute of Electrical and Electronics Engineers See IEEE. International Organization for Standardization See ISO. International Telecommunication Union See ITU. Internet Architecture Board See IAB. Internet Assigned Numbers Authority See IANA. Internet Corporation for Assigned Names and Numbers See ICANN. Internet Engineering Task Force See IETF. Internet Protocol See IP. Internet Protocol address See IP address. Internet service provider See ISP. Internet Society See ISOC. IP (Internet Protocol) A core protocol in the TCP/IP suite that operates in the Network layer of the OSI model and provides information about how and where data should be delivered. IP is the subprotocol that enables TCP/IP to internetwork. IP address (Internet Protocol address) The Network layer address assigned to nodes to uniquely identify them on a TCP/IP network. IPv4 addresses consist of 32 bits divided into four octets, or bytes. IPv6 addresses are composed of eight 16-bit fields, for a total of 128 bits. ISO (International Organization for Standardization) A collection of standards organizations representing 162 countries with headquarters located in Geneva, Switzerland. Its goal is to establish international technological standards to facilitate the global exchange of information and barrier-free trade. ISOC (Internet Society) A professional organization with members from 90 chapters around the world that helps to establish technical standards for the Internet. ISP (Internet service provider) A business that provides organizations and individuals with Internet access and often, other services, such as e-mail and Web hosting. ITU (International Telecommunication Union) A United Nations agency that regulates international telecommunications and provides developing countries with technical expertise and equipment to advance their technological bases. LLC (Logical Link Control) sublayer The upper sublayer in the Data Link layer. The LLC provides a common interface and supplies reliability and flow control services. logical address See network address. Logical Link Control sublayer See LLC (Logical Link Control) sublayer. MAC address See physical address. MAC (Media Access Control) sublayer The lower sublayer of the Data Link layer. The MAC appends the physical address of the destination computer onto the frame. maximum transmission unit See MTU. Media Access Control sublayer See MAC (Media Access Control) sublayer. MTU (maximum transmission unit) The largest data unit a network (for example, Ethernet or token ring) will accept for transmission. network address A unique identifying number for a network node that follows a hierarchical addressing scheme and can be assigned through operating system software. Network addresses are added to data packets and interpreted by protocols at the Network layer of the OSI model. Network layer The third layer in the OSI model. Protocols in the Network layer translate network addresses into their physical counterparts and decide how to route data from the sender to the receiver. Network layer address See network address. Open Systems Interconnection model See OSI (Open Systems Interconnection) model. Organizationally Unique Identifier See OUI. OSI (Open Systems Interconnection) model A model for understanding and developing computer-to-computer communication developed in the 1980s by ISO. It divides networking functions among seven layers: Physical, Data Link, Network, Transport, Session, Presentation, and Application. OUI (Organizationally Unique Identifier) A 24-bit character sequence assigned by IEEE that appears at the beginning of a network interface’s physical address and identifies the NIC’s manufacturer. PDU (protocol data unit) A unit of data at any layer of the OSI model. physical address A 48- or 64-bit network interface identifier that includes two parts: the OUI, assigned by IEEE to the manufacturer, and the extension identifier, a unique number assigned to each NIC by the manufacturer. Physical layer The lowest, or first, layer of the OSI model. Protocols in the Physical layer generate and detect signals so as to transmit and receive data over a network medium. These protocols also set the data transmission rate and monitor data error rates, but do not provide error correction. Presentation layer The sixth layer of the OSI model. Protocols in the Presentation layer translate between the application and the network. Here, data are formatted in a schema that the network can understand, with the format varying according to the type of network used. The Presentation layer also manages data encryption and decryption, such as the scrambling of system passwords. protocol data unit See PDU. reassembly The process of reconstructing data units that have been segmented. Regional Internet Registry See RIR. RIR (Regional Internet Registry) A not-for-profit agency that manages the distribution of IP addresses to private and public entities. ARIN is the RIR for North, Central, and South America and sub-Saharan Africa. APNIC is the RIR for Asia and the Pacific region. RIPE is the RIR for Europe and North Africa. route To intelligently direct data between networks based on addressing, patterns of usage, and availability of network segments. router A device that connects network segments and directs data based on information contained in the data packet. segment A unit of data that results from subdividing a larger protocol data unit. segmentation The process of decreasing the size of data units when moving data from a network that can handle larger data units to a network that can handle only smaller data units. sequencing The process of assigning a placeholder to each piece of a data block to allow the receiving node’s Transport layer to reassemble the data in the correct order. session A connection for data exchange between two parties. The term session may be used in the context of Web, remote access, or terminal and mainframe communications, for example. Session layer The fifth layer in the OSI model. The Session layer establishes and maintains communication between two nodes on the network. It can be considered the “traffic cop” for communications, such as videoconferencing, that require precisely coordinated data exchange. standard A documented agreement containing technical specifications or other precise criteria that are used as guidelines to ensure that materials, products, processes, and services suit their intended purpose. SYN (synchronization) The packet one node sends to request a connection with another node on the network. The SYN packet is the first of three in the three-step process of establishing a connection. SYN-ACK (synchronization-acknowledgment) The packet a node sends to acknowledge to another node that it has received a SYN request for connection. The SYN-ACK packet is the second of three in the three-step process of establishing a connection. synchronization See SYN. synchronization-acknowledgment See SYN-ACK. Telecommunications Industry Association See TIA. terminal A device with little (if any) of its own processing or disk capacity that depends on a host to supply it with applications and data-processing services. three-way handshake A three-step process in which Transport layer protocols establish a connection between nodes. The three steps are: Node A issues a SYN packet to node B, node B responds with SYN-ACK, and node A responds with ACK. TIA (Telecommunications Industry Association) A subgroup of the EIA that focuses on standards for information technology, wireless, satellite, fiber optics, and telephone equipment. Probably the best known standards to come from the TIA/EIA alliance are its guidelines for how network cable should be installed in commercial buildings, known as the “TIA/EIA 568-B Series.” token A special control frame that indicates to the rest of the network that a particular node has the right to transmit data. token ring A networking technology developed by IBM in the 1980s. It relies upon direct links between nodes and a ring topology, using tokens to allow nodes to transmit data. Transport layer The fourth layer of the OSI model. In the Transport layer, protocols ensure that data are transferred from point A to point B reliably and without errors. Transport layer services include flow control, acknowledgment, error correction, segmentation, reassembly, and sequencing. virtual address See network address. Chapter 3 Transmission Basics and Networking Media At a Glance Instructor’s Manual Table of Contents •Overview •Objectives •Teaching Tips •Quick Quizzes •Class Discussion Topics •Additional Projects •Additional Resources •Key Terms Lecture Notes Overview Media are the physical or atmospheric paths that signals follow. Originally, networks transmitted data over thick coaxial cables. Today, data transmits over cable sheathed in flexible plastic containing twisted copper wire inside. For long-distance network connections, fiber-optic cable is preferred. In addition, more and more organizations are sending signals through the atmosphere to form wireless networks. Because networks are always evolving and demanding greater speed, versatility, and reliability, networking media change rapidly. Network problems often occur at or below the Physical layer. Therefore, students should understand the characteristics of various networking media to design and troubleshoot networks. Students also need to know how data is transmitted over the media. This chapter discusses physical networking media and the details of data transmission. Students will learn what it takes to make data transmission dependable and how to correct some common transmission problems. Chapter Objectives After reading this chapter and completing the exercises, the student will be able to: •Explain basic data transmission concepts, including full duplexing, attenuation, latency, and noise •Describe the physical characteristics of coaxial cable, STP, UTP, and fiber-optic media •Compare the benefits and limitations of different networking media •Explain the principles behind and uses for serial connector cables •Identify wiring standards and the best practices for cabling buildings and work areas Teaching Tips Transmission Basics 1. Define and distinguish between the terms transmit, transmission and transceiver. Analog and Digital Signaling 1. Introduce the analog and digital signaling methods. 2. Describe how computers generate and interpret digital signals. 3. Define the term volt. 4. Explain the relationship of voltage to electrical signals. 5. Describe how signals travel over copper cabling, fiber-optic cable, and through the atmosphere. 6. Describe how analog signals are generated. 7. Use Figure 3-1 to illustrate how voltage varies continuously and appears as a wavy line when graphed over time. 8. Describe the four fundamental properties of analog signals: a. Amplitude b. Frequency c. Wavelength d. Phase 9. Use Figure 3-2 to illustrate waves with a 90-degree phase difference. 10. Describe the benefit of analog signals. 11. Describe the drawback of analog signals. 12. Introduce and define a digital signal. 13. Use Figure 3-3 to illustrate a digital signal. 14. Discuss the characteristics of a binary system. 15. Define a byte. 16. Define a bit and discuss its relationship to digital signals. 17. Explain how computers read and write information. 18. Explain how to find the decimal value of a bit. 19. Explain how to convert a byte to a decimal number. 20. Use Figure 3-4 to illustrate the components of a byte. 21. Explain how to convert a decimal number to a byte. Teaching Tip Use a computer to demonstrate how to convert the decimal number 131 to binary by using the Windows Calculator. In addition, go to http://www.google.com and type “131 in binary” (no quotes) on the Google search box and press the Enter key. 22. Describe the benefit of digital signals: a. Reliability b. Noise interference reduced 23. Define and describe overhead. 24. Explain why it is important to understand the signaling techniques in both the analog and digital worlds. Teaching Tip Students may find more information on analog and digital transmission properties at http://library.thinkquest.org/27887/gather/fundamentals/analog_and_digital.shtml Quick Quiz 1 1. Which term means to issue signals along a network medium such as a cable? a. Transmission b. Transmit c. Transceiver d. Transistor Answer: B 2. Computers generate and interpret digital signals as electrical current, the pressure of which is measured in ____. Answer: volts 3. Which term represents an analog wave’s strength? a. Phase b. Wavelength c. Frequency d. Amplitude Answer: D 4. A(n) ____ contains eight bits. Answer: byte 5. True or False: The reduction of noise interference is a benefit of digital signal transmissions. Answer: True Data Modulation 1. Explain why the conversion between digital and analog signals is necessary. 2. Describe a modem and explain its purpose. 3. Define and describe data modulation. 4. Define and describe a carrier wave. 5. Define and describe an information wave. 6. Define and explain how frequency modulation works. 7. Define and explain how amplitude modulation works. 8. Use Figure 3-5 to illustrate how a carrier wave is modified through frequency modulation. Simplex, Half-Duplex, and Duplex 1. Define and discuss simplex transmission. 2. Define and discuss half-duplex transmission. 3. Define and discuss full-duplex transmission. 4. Use Figure 3-6 to illustrate the three transmission types. 5. Define and describe a channel. 6. Describe the advantage of full-duplex transmission. Multiplexing 1. Define multiplexing. 2. Explain how multiple signals are carried using subchannels. 3. Define and explain the use of a multiplexer. 4. Define and explain the use of a demultiplexer. 5. Define and describe TDM (time division multiplexing). 6. Use Figure 3-7 to illustrate time division multiplexing. 7. Define and describe statistical multiplexing. 8. Use Figure 3-8 to illustrate statistical multiplexing. 9. Explain why statistical multiplexing is more efficient than TDM. 10. Define and describe FDM (frequency division multiplexing). 11. Use Figure 3-9 to illustrate frequency division multiplexing. 12. Define and describe WDM (wavelength division multiplexing). 13. Use Figure 3-10 to illustrate wavelength division multiplexing. 14. Define and describe DWDM (dense wavelength division multiplexing). Relationships Between Nodes 1. Define and describe point-to-point transmission. 2. Define and describe point-to-multipoint transmission. 3. Describe the two types of point-to-multipoint transmission: a. Broadcast b. Nonbroadcast 4. Use Figure 3-11 to illustrate the differences in the two transmission types. Throughput and Bandwidth 1. Define and describe throughput. 2. Mention that that the terms throughput and bandwidth are often interchanged. 3. Use Table 3-1 to illustrate various measures of throughput. 4. Define and describe a strict definition of bandwidth. Baseband and Broadband 1. Define and describe baseband. 2. Define and describe broadband. Transmission Flaws 1. Introduce and define transmission flaws. 2. Define and describe noise. 3. Describe the types of noise. a. EMI (electromagnetic interference) b. Crosstalk c. Environmental influences 4. Use Figure 3-12 to illustrate crosstalk. 5. Ensure that students understand the causes of near end cross talk (NEXT). 6. Define and describe attenuation. 7. Describe the methods of reducing the effects of attenuation for each type of transmission signal. a. Analog - amplifiers b. Digital - repeaters 8. Emphasize that with amplifiers, noise is also amplified. 9. Note that amplifiers and repeaters operate at the physical layer of the OSI model. 10. Use Figure 3-13 and 3-14 to illustrate analog and digital signals distorted by noise and then amplified. 11. Define and describe latency. 12. Discuss potential causes of latency, 13. Note that different devices affect latency to different degrees. 14. Define and describe the most common way to measure latency on data networks. 15. Explain why latency causes problems. 16. Explain how to constrain latency and avoid its associated errors. Common Media Characteristics 1. Describe the factors to consider when deciding which kind of transmission media to use. 2. Introduce the characteristics of several types of physical media. a. Throughput b. Cost c. Size and scalability d. Connectors and Media Converters e. Noise immunity Throughput 1. Emphasize that throughput is perhaps the most significant factor in choosing a transmission method. 2. Describe the causes of throughput limitation: a. Laws of physics b. Signaling and multiplexing techniques c. Noise d. Devices connected to transmission medium 3. Note that using fiber-optic cables allows faster throughput than copper or wireless connections. Cost 1. Emphasize that the precise costs of using a particular type of cable or wireless connection are often difficult to pinpoint. 2. Describe factors affecting media costs: a. Existing hardware b. Network size c. Labor costs 3. Describe the variables influencing the final cost of implementing a certain type of media: a. Cost of installation b. Cost of new infrastructure versus reusing existing infrastructure c. Cost of maintenance and support d. Cost of a lower transmission rate affecting productivity e. Cost of obsolescence Noise Immunity 1. Remind students that noise can distort data signals. 2. Explain how the extent to which noise affects a signal depends partly on the transmission media. 3. Emphasize that noise is an ever-present threat. 4. Describe measures to limit its impact on a network. 5. Point out that wireless signals are more apt to be distorted by EMI/RFI than signals traveling over a cable. 6. Explain that it is also possible to use antinoise algorithms to protect data from being corrupted by noise. Size and Scalability 1. Explain the three specifications determining the size and scalability of networking media. 2. Describe how the maximum number of nodes per segment depends on attenuation and latency. 3. Describe how the maximum segment length depends on attenuation and latency plus the segment type. 4. Define a populated segment. 5. Define an unpopulated segment. 6. Describe why segment lengths are limited. Connectors and Media Converters 1. Define and describe a connector. 2. Emphasize that connectors are specific to a particular media type. 3. Point out that connector specificity does not prevent one network from using multiple media. 4. Describe a media converter. 5. Use Figure 3-15 to illustrate a media converter. Quick Quiz 2 1. Which type of modulation occurs when the amplitude of the carrier signal is modified by the application of the data signal? a. Statistical modulation b. Frequency modulation c. Amplitude modulation d. Data modulation Answer: C 2. In ____ multiplexing, the transmitter assigns slots to nodes according to priority and need. a. statistical b. frequency division c. wavelength division d. dense wavelength division Answer: A 3. A(n) ____ point-to-multipoint transmission issues signals to multiple, defined recipients. Answer: Nonbroadcast 4. True or False: Broadband technology encodes information as digital pulses. Answer: True 5. True or False: EMI (electromagnetic interference) is a latency issue. Answer: False 6. A(n) ____ is used to reduce the effects of attenuation for a digital transmission signal. Answer: repeater Coaxial Cable 1. Define and describe a coaxial cable. 2. Use Figure 3-16 to illustrate a coaxial cable. 3. Explain why most coaxial cable has a high resistance to noise. 4. Describe the advantages of coaxial cable over twisted pair. 5. Explain why coaxial cable is more expensive than twisted pair cable. 6. Note that coaxial cabling comes in hundreds of specifications. 7. Point out that students will most likely see only two or three types of coax in use on data networks. 8. Explain the RG specification number convention. 9. Describe the significant differences between cable types. 10. Point out that when discussing the size of the conducting core in a coaxial cable, its American Wire Gauge (AWG) size is often referenced. 11. Explain the coaxial cable specifications used with data networks. a. RG-6 b. RG-8 c. RG-58 d. RG-59 12. Explain the two terminating connector types: a. F-type connector b. BNC connector 13. Note that RG-6 and RG-59 can terminate with one of two connector types. 14. Use Figure 3-17 to illustrate an F-type connector. 15. Use Figure 3-18 to illustrate a BNC connector. Teaching Tip For more information on F-type and BNC connectors, students may reference http://en.wikipedia.org/wiki/F_connector and http://en.wikipedia.org/wiki/BNC_connector. Twisted Pair Cable 1. Introduce and describe twisted pair cabling. 2. Use Figure 3-19 to illustrate twisted pair cabling. 3. Point out that the number of pairs in a cable varies, depending on the cable type. 4. Explain the wire characteristics when there are twists per foot in a pair of wires. 5. Describe twist ratio and explain the issue with attenuation. 6. Explain the factors contributing to the hundreds of design variations. 7. Discuss the twisted pair wiring standard, “TIA/EIA 568”. 8. Note the types of twisted pair wiring most often mentioned. 9. Point out that Cat 5 is most often used in modern LANs. 10. Describe the advantages of twisted pair cable. 11. Introduce the two categories of twisted pair cable: a. STP (shielded twisted pair) b. UTP (unshielded twisted pair) STP (Shielded Twisted Pair) 1. Define and describe STP. 2. Use Figure 3-20 to illustrate STP. UTP (Unshielded Twisted Pair) 1. Define and describe UTP. 2. Use Figure 3-21 to illustrate UTP. 3. Discuss the categories used on modern networks: a. Cat 3 (Category 3) b. Cat 4 (Category 4) c. Cat 5 (Category 5) d. Cat 5e (Enhanced Category 5) e. Cat 6 (Category 6) f. Cat 6a (Augmented Category 6) g. Cat 7 (Category 7) 4. Use Figure 3-22 to depict a typical Cat 5 UTP cable. 5. Explain why Cat 6 and Cat 7 are more similar to shielded twisted pair. 6. Note that UTP cabling may be used with any one of several IEEE Physical layer-networking standards that specify throughput maximums of 10, 100, 1000, and even 10,000 Mbps. Comparing STP and UTP 1. Describe the similarities and differences between STP and UTP. 2. Use Figure 3-23 to illustrate RJ-45 and RJ-11 connectors. 3. Ensure that students understand the throughput, cost, connector, noise immunity, and size and scalability parameters of twisted-pair cables. Terminating Twisted Pair Cable 1. Define a patch cable. 2. Explain why closely following proper termination techniques is critical. 3. Identify the two TIA/EIA standards for terminating twisted pair cable: a. TIA/EIA 568A b. TIA/EIA 568B 4. Note that the standards are functionally equivalent and how they must be implemented. 5. Use Figure 3-24 to illustrate TIA/EIA 568A standard terminations. 6. Use Figure 3-25 to illustrate TIA/EIA 568B standard terminations. 7. Define a straight-through cable and discuss situations where it may be used. 8. Define a crossover cable and discuss situations where it may be used. 9. Use Figure 3-26 to illustrate RJ-45 terminations on a crossover cable. 10. Point out that only pairs 2 and 3 are switched, because those are the pairs sending and receiving data. 11. Mention the tools required to terminate twisted-pair cable with an RJ-45 plug, using Figures 3-27, 3-28, and 3-29 to describe these tools. 12. Explain the steps to create a straight-through patch cable. 13. Explain how to modify the steps to create a cross over cable. 14. Mention that it is good practice to verify that newly made cables can transmit and receive data at the necessary rates using a cable tester. Fiber-Optic Cable 1. Introduce and define fiber-optic cable. 2. Describe how data is transmitted. 3. Define and explain cladding. 4. Explain the purpose of the plastic buffer. 5. Explain how to prevent the cable from stretching. 6. Describe the strands of Kevlar and its purpose. 7. Note the plastic sheath that covers the strands of Kevlar. 8. Use Figure 3-30 to illustrate a fiber-optic cable. 9. Note that there are different varieties of fiber-optic cable depending on its intended use and the manufacturer. 10. Introduce the two categories of fiber-optic cable: a. Single-mode b. Multimode 11. Use Figure 3-33 to illustrate a ST (straight tip) connector. 12. Use Figure 3-32 to illustrate a SC (subscriber connector or standard connector). 13. Use Figure 3-34 to illustrate a LC (local connector). 14. Use Figure 3-35 to illustrate a MT-RJ (mechanical transfer registered jack). 15. Discuss the characteristics of fiber optic cable: a. Throughput b. Costs c. Connector d. Noise immunity e. Size and scalability SMF (Single-Mode Fiber) 1. Describe SMF (single-mode fiber). 2. Explain the benefits of SMF. 3. Describe the drawback of SMF. 4. Use Figure 3-36 to illustrate transmission over single-mode fiber-optic cable. MMF (Multimode Fiber) 1. Describe MMF (multimode fiber). 2. Explain the common uses of multimode fiber. 3. Describe the benefits of MMF. 4. Describe the drawback of MMF. 5. Use Figure 3-37 to illustrate transmission over multimode fiber-optic cable. 6. Describe the benefits of MMF. 7. Describe the drawbacks of MMF. Teaching Tip Students may find more information on media at http://library.thinkquest.org/27887/gather/fundamentals/media.shtml Teaching Tip Students may find more information on Fiber-Optic and Satellite Communications at http://technet.microsoft.com/en-us/library/bb726936.aspx Serial Cables 1. Define the term serial. 2. Define a serial connection. 3. Describe the EIA/TIA serial data transmission. 4. Explain the connection types for RS-232. 5. Use Figure 3-40 to illustrate a DB-9 connector. 6. Use Figure 3-41 to illustrate a DB-25 connector. Teaching Tip Point out that the arrangement of the pins on both connectors resembles a sideways letter D. 7. Discuss where RS-232 connections are likely to be used in today’s networks. 8. Describe how the termination points on RS-232 cables can be arranged in various ways: a. Straight-through b. Crossover Structured Cabling 1. Define a cabling plant. 2. Describe the TIA/EIA joint 568 Commercial Building Wiring Standard. 3. Use Table 3-2 to illustrate TIA/EIA specifications for backbone cabling. 4. Use Figure 3-42 to illustrate the different components of structured cabling in an enterprise from a bird’s eye view. 5. Use Figure 3-43 to illustrate how structured cabling appears within a building. 6. Review the components referenced in Figure 3-42 and Figure 3-43: a. Entrance facilities b. MDF (main distribution frame) c. Cross-connect facilities d. IDF (intermediate distribution frame) e. Backbone wiring f. Telecommunications closet g. Horizontal wiring h. Work area 7. Use Figure 3-44 to illustrate a patch panel. 8. Use Figure 3-45 to illustrate a punch-down block. 9. Use Figure 3-46 to illustrate a horizontal wiring configuration. 10. Use Figure 3-47 to illustrate a standard TIA/EIA outlet. 11. Use Figure 3-48 illustrates a cable installation using UTP from the telecommunications closet to the work area. Best Practices for Cable Installation and Management 1. Explain the best way to choose the correct cabling and make it work with a network. 2. Explain the cause of many cabling problems. 3. Discuss the various cable installation tips. Teaching Tip Emphasize the vast knowledge required when specializing in cable installation, design, or maintenance, and the importance of investing in a reference dedicated to this topic. Teaching Tip Students may find more information on Cable Considerations for Network Installations at http://support.microsoft.com/kb/97550 Quick Quiz 3 1. True or False: Coaxial cable has a high resistance to noise. Answer: True 2. True or False: A high twist ratio can result in lower attenuation. Answer: False 3. Which cabling consists of one or more insulated wire pairs encased in a plastic sheath? a. UTP (unshielded twisted pair) b. STP (Shielded twisted pair c. Coaxial d. Fiber-optic Answer: A 4. A(n) ____cable is a patch cable in which the termination locations of the transmit and receive wires on one end of the cable are reversed. a. straight-through b. rollover c. crossover d. cross-through Answer: C 5. True or False: Fiber-optic cable is the most expensive transmission medium. Answer: True Class Discussion Topics 1. Discuss why it is critical to follow termination standards. Are there any disadvantages to following these standards? 2. Discuss how to determine which cabling type to use in a network. Ask students to share their personal experiences from their workplaces. Additional Projects 1. Have each student research the three tools to terminate a twisted-pair cable with an RJ-45 plug: wire cutter, wire stripper, and crimping tool. The research report should include a write-up explaining what each tool does in the context of terminating twisted pair wire. The students should find five Web site prices and pictures (if possible) for each tool and present the research in tabular form. Finally, the student should find an example of a combination tool that perform two or more of the functions and provide the Web site and the cost for such a tool. 2. Have the students research the costs comparisons for purchasing 500 feet of the three cabling transmission media: coaxial cable, twisted pair cable, and fiber-optic cable. The research should include two cable types from each of the three cabling transmission media. The students should present their findings in written report format. Additional Resources 1. EIA/TIA sites http://www.eia.org http://www.tiaonline.org 2. Blackbox Network Services http://www.blackbox.com 3. How Fiber Optics Work http://www.howstuffworks.com/fiber-optic.htm 4. Network Cabling Help http://www.datacottage.com Key Terms 1 gigabit per second (Gbps) 1,000,000,000 bits per second. 1 kilobit per second (Kbps) 1000 bits per second. 1 megabit per second (Mbps) 1,000,000 bits per second. 1 terabit per second (Tbps) 1,000,000,000,000 bits per second. 100-pair wire UTP supplied by a telecommunications carrier that contains 100 wire pairs. 110 block Part of an organization’s cross-connect facilities, a type of punch-down block designed to terminate Cat 5 or better twisted pair wires. 25-pair wire UTP supplied by a telecommunications carrier that contains 25 wire pairs. alien cross talk EMI interference induced on one cable by signals traveling over a nearby cable. AM (amplitude modulation) A modulation technique in which the amplitude of the carrier signal is modified by the application of a data signal. American Wire Gauge See AWG. amplifier A device that boosts, or strengthens, an analog signal. amplitude A measure of a signal’s strength. amplitude modulation See AM. analog A signal that uses variable voltage to create continuous waves, resulting in an inexact transmission. attenuation The extent to which a signal has weakened after traveling a given distance. augmented Category 6 See Cat 6a. AWG (American Wire Gauge) A standard rating that indicates the diameter of a wire, such as the conducting core of a coaxial cable. bandwidth A measure of the difference between the highest and lowest frequencies that a medium can transmit. baseband A form of transmission in which digital signals are sent through direct current pulses applied to a wire. This direct current requires exclusive use of the wire’s capacity, so baseband systems can transmit only one signal, or one channel, at a time. Every device on a baseband system shares a single channel. bend radius The radius of the maximum arc into which you can loop a cable before you will cause data transmission errors. Generally, a twisted pair cable’s bend radius is equal to or greater than four times the diameter of the cable. binary A system founded on using 1s and 0s to encode information. bit (binary digit) A bit equals a single pulse in the digital encoding system. It may have only one of two values: 0 or 1. BNC (Bayonet Neill-Concelman, or British Naval Connector) A standard for coaxial cable connectors named after its coupling method and its inventors. BNC connector A coaxial cable connector type that uses a twist-and-lock (or bayonet) style of coupling. It may be used with several coaxial cable types, including RG-6 and RG-59. braiding A braided metal shielding used to insulate some types of coaxial cable. broadband A form of transmission in which signals are modulated as radio frequency analog pulses with different frequency ranges. Unlike baseband, broadband technology does not involve binary encoding. The use of multiple frequencies enables a broadband system to operate over several channels and, therefore, carry much more data than a baseband system. broadcast A transmission that involves one transmitter and multiple, undefined receivers. byte Eight bits of information. In a digital signaling system, broadly speaking, 1 byte carries one piece of information. cable plant The hardware that constitutes the enterprise-wide cabling system. capacity See throughput. Cat Abbreviation for the word category when describing a type of twisted pair cable. For example, Category 5 unshielded twisted pair cable may also be called Cat 5. Cat 3 (Category 3) A form of UTP that contains four wire pairs and can carry up to 10 Mbps, with a possible bandwidth of 16 MHz. Cat 3 was used for 10-Mbps Ethernet or 4-Mbps token ring networks. Cat 5 (Category 5) A form of UTP that contains four wire pairs and supports up to 100-Mbps throughput and a 100-MHz signal rate. Cat 5e (Enhanced Category 5) A higher-grade version of Cat 5 wiring that contains high-quality copper, offers a high twist ratio, and uses advanced methods for reducing cross talk. Enhanced Cat 5 can support a signaling rate of up to 350 MHz, more than triple the capability of regular Cat 5. Cat 6 (Category 6) A twisted pair cable that contains four wire pairs, each wrapped in foil insulation. Additional foil insulation covers the bundle of wire pairs, and a fire-resistant plastic sheath covers the second foil layer. The foil insulation provides excellent resistance to cross talk and enables Cat 6 to support a signaling rate of 250 MHz and at least six times the throughput supported by regular Cat 5. Cat 6a (Augmented Category 6) A higher-grade version of Cat 6 wiring that further reduces attenuation and cross talk and allows for potentially exceeding traditional network segment length limits. Cat 6a is capable of a 500-MHz signaling rate and can reliably transmit data at multi-gigabit per second rates. Cat 7 (Category 7) A twisted pair cable that contains multiple wire pairs, each separately shielded then surrounded by another layer of shielding within the jacket. Cat 7 can support up to a 1-GHz signal rate. But because of its extra layers, it is less flexible than other forms of twisted pair wiring. Category 3 See Cat 3. Category 5 See Cat 5. Category 6 See Cat 6. Category 7 See Cat 7. channel A distinct communication path between two or more nodes, much like a lane is a distinct transportation path on a freeway. Channels may be separated either logically (as in multiplexing) or physically (as when they are carried by separate wires). cladding The glass or plastic shield around the core of a fiber-optic cable. Cladding reflects light back to the core in patterns that vary depending on the transmission mode. This reflection allows fiber to bend around corners without impairing the light-based signal. coaxial cable A type of cable that consists of a central metal conducting core, which might be solid or stranded and is often made of copper, surrounded by an insulator, a braided metal shielding, called braiding, and an outer cover, called the sheath or jacket. Coaxial cable, called “coax” for short, was the foundation for Ethernet networks in the 1980s. Today it is used to connect cable Internet and cable TV systems. conduit The pipeline used to contain and protect cabling. Conduit is usually made from metal. connectors The pieces of hardware that connect the wire to the network device, be it a file server, workstation, switch, or printer. core The central component of a cable designed to carry a signal. The core of a fiber-optic cable, for example, consists of one or several glass or plastic fibers. The core of a coaxial copper cable consists of one large or several small strands of copper. crossover cable A twisted pair patch cable in which the termination locations of the transmit and receive wires on one end of the cable are reversed. cross talk A type of interference caused by signals traveling on nearby wire pairs infringing on another pair’s signal. DB-9 connector A type of connector with nine pins that’s commonly used in serial communication that conforms to the RS-232 standard. DB-25 connector A type of connector with 25 pins that’s commonly used in serial communication that conforms to the RS-232 standard. demarc See demarcation point. demarcation point (demarc) The point of division between a telecommunications service carrier’s network and a building’s internal network. demultiplexer (demux) A device that separates multiplexed signals once they are received and regenerates them in their original form. demux See demultiplexer dense wavelength division multiplexing See DWDM. digital As opposed to analog signals, digital signals are composed of pulses that can have a value of only 1 or 0. duplex See full-duplex. DWDM (dense wavelength division multiplexing) A multiplexing technique used over single-mode or multimode fiber-optic cable in which each signal is assigned a different wavelength for its carrier wave. In DWDM, little space exists between carrier waves in order to achieve extraordinary high capacity. electromagnetic interference See EMI. EMI (electromagnetic interference) A type of interference that may be caused by motors, power lines, televisions, copiers, fluorescent lights, or other sources of electrical activity. Enhanced Category 5 See Cat 5e. entrance facilities The facilities necessary for a service provider (whether it is a local phone company, Internet service provider, or long-distance carrier) to connect with another organization’s LAN or WAN. FDM (frequency division multiplexing) A type of multiplexing that assigns a unique frequency band to each communications subchannel. Signals are modulated with different carrier frequencies, then multiplexed to simultaneously travel over a single channel. ferrule A short tube within a fiber-optic cable connector that encircles the fiber strand and keeps it properly aligned. fiber-optic cable A form of cable that contains one or several glass or plastic fibers in its core. Data is transmitted via pulsing light sent from a laser or light-emitting diode (LED) through the central fiber (or fibers). Fiber-optic cables offer significantly higher throughput than copper-based cables. They may be single-mode or multimode and typically use wave-division multiplexing to carry multiple signals. FM (frequency modulation) A method of data modulation in which the frequency of the carrier signal is modified by the application of the data signal. frequency The number of times that a signal’s amplitude changes over a fixed period of time, expressed in cycles per second, or hertz (Hz). frequency division multiplexing See FDM. frequency modulation See FM. F-Type connector A connector used to terminate coaxial cable used for transmitting television and broadband cable signals. full-duplex A type of transmission in which signals may travel in both directions over a medium simultaneously. May also be called, simply, “duplex.” half-duplex A type of transmission in which signals may travel in both directions over a medium, but in only one direction at a time. hertz (Hz) A measure of frequency equivalent to the number of amplitude cycles per second. IDF (intermediate distribution frame) A junction point between the MDF and concentrations of fewer connections—for example, those that terminate in a telecommunications closet. impedance The resistance that contributes to controlling an electrical signal. Impedance is measured in ohms. intermediate distribution frame See IDF. latency The delay between the transmission of a signal and its receipt. LC (local connector) A connector used with single-mode or multimode fiber-optic cable. link segment See unpopulated segment. local connector See LC. main cross-connect See MDF. main distribution frame See MDF. MDF (main distribution frame) Also known as the main cross-connect, the first point of interconnection between an organization’s LAN or WAN and a service provider’s facility. mechanical transfer registered jack See MT-RJ. media converter A device that enables networks or segments using different media to interconnect and exchange signals. MMF (multimode fiber) A type of fiber-optic cable that contains a core with a diameter between 50 and 100 microns, through which many pulses of light generated by a light-emitting diode (LED) travel at different angles. modem A device that modulates analog signals into digital signals at the transmitting end for transmission over telephone lines, and demodulates digital signals into analog signals at the receiving end. modulation A technique for formatting signals in which one property of a simple carrier wave is modified by the addition of a data signal during transmission. MT-RJ (mechanical transfer registered jack) A connector used with single-mode or multimode fiber-optic cable. multimode fiber See MMF. multiplexer A device that separates a medium into multiple channels and issues signals to each of those subchannels. multiplexing A form of transmission that allows multiple signals to travel simultaneously over one medium. near end cross talk See NEXT. NEXT (near end cross talk) Cross talk, or the impingement of the signal carried by one wire onto a nearby wire, that occurs between wire pairs near the source of a signal. noise The unwanted signals, or interference, from sources near network cabling, such as electrical motors, power lines, and radar. nonbroadcast point-to-multipoint transmission A communications arrangement in which a single transmitter issues signals to multiple, defined recipients. optical loss The degradation of a light signal on a fiber-optic network. overhead The nondata information that must accompany data for a signal to be properly routed and interpreted by the network. patch cable A relatively short section (usually between 3 and 25 feet) of cabling with connectors on both ends. patch panel A wall-mounted panel of data receptors into which cross-connect patch cables from the punch-down block are inserted. phase A point or stage in a wave’s progress over time. plenum The area above the ceiling tile or below the subfloor in a building. point-to-multipoint A communications arrangement in which one transmitter issues signals to multiple receivers. The receivers may be undefined, as in a broadcast transmission, or defined, as in a nonbroadcast transmission. point-to-point A data transmission that involves one transmitter and one receiver. populated segment A network segment that contains end nodes, such as workstations. punch-down block A panel of data receptors into which twisted pair wire is inserted, or punched down, to complete a circuit. radio frequency interference See RFI. Recommended Standard 232 See RS-232. regeneration The process of retransmitting a digital signal. Regeneration, unlike amplification, repeats the pure signal, with none of the noise it has accumulated. registered jack 11 See RJ-11. registered jack 45 See RJ-45. repeater A device used to regenerate a signal. RFI (radio frequency interference) A kind of interference that may be generated by broadcast signals from radio or TV antennas. RG-6 A type of coaxial cable with an impedance of 75 ohms and that contains an 18 AWG core conductor. RG-6 is used for television, satellite, and broadband cable connections. RG-8 A type of coaxial cable characterized by a 50-ohm impedance and a 10 AWG core. RG-8 provided the medium for the first Ethernet networks, which followed the now-obsolete 10BASE-5 standard. RG-58 A type of coaxial cable characterized by a 50-ohm impedance and a 24 AWG core. RG-58 was a popular medium for Ethernet LANs in the 1980s, used for the now-obsolete 10BASE-2 standard. RG-59 A type of coaxial cable characterized by a 75-ohm impedance and a 20 or 22 AWG core, usually made of braided copper. Less expensive but suffering greater attenuation than the more common RG-6 coax, RG-59 is used for relatively short connections. RJ-11 (registered jack 11) The standard connector used with unshielded twisted pair cabling (usually Cat 3 or Level 1) to connect analog telephones. RJ-45 (registered jack 45) The standard connector used with shielded twisted pair and unshielded twisted pair cabling. round-trip time See RTT. RS-232 (Recommended Standard 232) A Physical layer standard for serial communications, as defined by EIA/TIA. RTT (round-trip time) The length of time it takes for a packet to go from sender to receiver, then back from receiver to sender. RTT is usually measured in milliseconds. SC (subscriber connector or standard connector) A connector used with single-mode or multimode fiber-optic cable. serial A style of data transmission in which the pulses that represent bits follow one another along a single transmission line. In other words, they are issued sequentially, not simultaneously. serial cable A cable, such as an RS-232 type, that permits serial data transmission. sheath The outer cover, or jacket, of a cable. shield See braiding. shielded twisted pair See STP. simplex A type of transmission in which signals may travel in only one direction over a medium. single-mode fiber See SMF. SMF (single-mode fiber) A type of fiber-optic cable with a narrow core that carries light pulses along a single path data from one end of the cable to the other end. Data can be transmitted faster and for longer distances on single-mode fiber than on multimode fiber. However, single-mode fiber is more expensive. ST (straight tip) A connector used with single-mode or multimode fiber-optic cable. standard connector See SC. statistical multiplexing A method of multiplexing in which each node on a network is assigned a separate time slot for transmission, based on the node’s priority and need. STP (shielded twisted pair) A type of cable containing twisted-wire pairs that are not only individually insulated, but also surrounded by a shielding made of a metallic substance such as foil. straight-through cable A twisted pair patch cable in which the wire terminations in both connectors follow the same scheme. straight tip See ST. structured cabling A method for uniform, enterprise-wide, multivendor cabling systems specified by the TIA/EIA 568 Commercial Building Wiring Standard. Structured cabling is based on a hierarchical design using a high-speed backbone. subchannel One of many distinct communication paths established when a channel is multiplexed or modulated. subscriber connector See SC. TDM (time division multiplexing) A method of multiplexing that assigns a time slot in the flow of communications to every node on the network and, in that time slot, carries data from that node. telecommunications closet Also known as a “telco room,” the space that contains connectivity for groups of workstations in a defined area, plus cross-connections to IDFs or, in smaller organizations, an MDF. Large organizations may have several telecommunications closets per floor, but the TIA/EIA standard specifies at least one per floor. Thicknet An IEEE Physical layer standard for achieving a maximum of 10-Mbps throughput over coaxial copper cable. Thicknet is also known as 10Base-5. Its maximum segment length is 500 meters, and it relies on a bus topology. Thinnet An IEEE Physical layer standard for achieving 10-Mbps throughput over coaxial copper cable. Thinnet is also known as 10Base-2. Its maximum segment length is 185 meters, and it relies on a bus topology. throughput The amount of data that a medium can transmit during a given period of time. Throughput is usually measured in megabits (1,000,000 bits) per second, or Mbps. The physical nature of every transmission media determines its potential throughput. time division multiplexing See TDM. transceiver A device that transmits and receives signals. transmission In networking, the application of data signals to a medium or the progress of data signals over a medium from one point to another. transmit To issue signals to the network medium. twist ratio The number of twists per meter or foot in a twisted pair cable. twisted pair A type of cable similar to telephone wiring that consists of color-coded pairs of insulated copper wires, each with a diameter of 0.4 to 0.8 mm, twisted around each other and encased in plastic coating. unpopulated segment A network segment that does not contain end nodes, such as workstations. Unpopulated segments are also called link segments. unshielded twisted pair See UTP. UTP (unshielded twisted pair) A type of cabling that consists of one or more insulated wire pairs encased in a plastic sheath. As its name implies, UTP does not contain additional shielding for the twisted pairs. As a result, UTP is both less expensive and less resistant to noise than STP. vertical cross-connect Part of a network’s backbone that supplies connectivity between a building’s floors. For example, vertical cross-connects might connect an MDF and an IDF or IDFs and telecommunications closets within a building. volt The measurement used to describe the degree of pressure an electrical current exerts on a conductor. voltage The pressure (sometimes informally referred to as the strength) of an electrical current. wavelength The distance between corresponding points on a wave’s cycle. Wavelength is inversely proportional to frequency. wavelength division multiplexing See WDM. WDM (wavelength division multiplexing) A multiplexing technique in which each signal on a fiber-optic cable is assigned a different wavelength, which equates to its own subchannel. Each wavelength is modulated with a data signal. In this manner, multiple signals can be simultaneously transmitted in the same direction over a length of fiber. zipcord cable A relatively short fiber-optic cable in which two strands are arranged side by side in conjoined jackets, enabling full-duplex communication. Instructor Manual for Network+ Guide to Networks Tamara Dean 9781133608196, 9781133608257, 9781337569330
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