This Document Contains Chapters 4 to 7 Chapter 4 Network 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 • Technical Notes for Hands-On Projects Lecture Notes Overview Chapter 4 will introduce students to the primary cables used in wired networking. They also learn the characteristics of the major types of fiber-optic media. At the end of the chapter, students will be able to explain the technologies used for wireless networking. Objectives • Define the primary cables used in wired networking • Describe the characteristics of the major types of fiber-optic media • Explain the technologies used for wireless networking Teaching Tips Wired Networking 1. Explain what wired networking implies as a term, and the types of cables most broadly used in wired networking: copper wire and fiber optic. Criteria for Choosing Network Media 1. Discuss with students the various criteria to consider when choosing networking media for a network installation. a. Bandwidth will be one of the key areas for choosing network media. Explain to students what determines bandwidth for a given media type and how encoding affects transmission speeds. b. Students should be taught to consider factors such as cable grades when selecting network media, to ensure compatibility with future protocols. c. Discuss how cable length influences network media choices and that signal attenuation should be considered. Ethernet on CAT5 UTP will have different length and capabilities than fiber-optic media. d. Explain to students the possible side effects of interference on network media, specifically how electromagnetic interference (EMI) and radio frequency interference (RFI) can degrade a signal. Crosstalk is also an issue with copper media. e. Discuss various media’s susceptibility to users with malicious intent. With some ingenuity and a protocol analyzer, someone could easily get sensitive information out of your network traffic. f. Students need to be aware that cable grades often have to comply with fire codes. Standard PVC covers that are common on most UTP cables give off toxic fumes when burned. Explain when safer (but more expensive) plenum cables should be used instead of PVC-jacketed UTP cables. g. Illustrate how connectors on various media types will affect hardware choices and cost. Compare the cost of UTP connectors (cheap) to fiber-optic connectors (expensive). h. Discuss the other considerations that come into play when selecting media. Specifically, ease of installation, testability, and cost. Scalability and flexibility are examples of still other factors that might be mentioned. Teaching Tip When discussing media’s susceptibility, it might be helpful to later direct students to research the following topics: 1. ARP spoofing 2. Fiber-optic eavesdropping 3. Wardriving Coaxial Cable 1. Explain that coaxial cable, while cheap and easy to install, is mostly only used in networking when connecting a cable modem. Twisted-Pair Cable 1. Discuss the two types of twisted-pair cable, unshielded and shielded. Make sure students understand the difference between the two and how shielded twisted pair works to improve resistance to crosstalk and EMI. 2. Demonstrate the different categories when referring to cabling and how categories govern the number of twists per foot or meter. 3. Describe the shielding used for shielded twisted-pair cable. Let students know that different methods of shielding exist, including wrapping foil around each wire pair versus wrapping foil around all wire pairs together. Twisted-Pair Cable Plant Components 1. Show students uncrimped versions of RJ-45 connectors. Make the comparison of the RJ-45 jack to the common modular telephone RJ-11 jacks. Oftentimes, people will mistake one for the other. 2. Explain what a patch panel is and how it adds flexibility by allowing quick reconfiguration of long runs of cable. This is especially useful when wall plates are used to connect client PCs because it can help keep track of which wall plate goes where. 3. Explain how patch cables are used with patch panels, and if possible, demonstrate using a live patch panel and patch cables. Structured Cabling: Managing and Installing a UTP Cable Plant 1. Describe what is meant by “structured cabling”, namely the TIA/EIA “568 Commercial Building Wiring Standard”. a. Structured cabling simply specifies how cables should be organized regardless of media types, based on an extended physical star topology. b. You should make students aware of the six cable plant components: i. Work area ii. Horizontal wiring iii. Telecommunications closets iv. Equipment rooms v. Backbone or vertical wiring vi. Entrance facilities c. Detail the requirements of each component. For example, the horizontal wiring should not exceed 100 meters, which includes the cable running from the wall jack to the patch panel plus all patch panels. (To make this calculation easier, cut the cable from the wall jack to the patch panel off at around 90 meters, and allow 10 meters for patch cables). d. List some of the typical equipment found inside of a telecommunications closet. e. Explain to students how equipment rooms serve as a connection point for backbone cabling for TCs and what kind of equipment can be found in one. f. Describe how backbone cabling is used, and explain the different media types used depending on different circumstances. For example, backbone cabling between buildings is most commonly fiber optic, but backbone cabling between individual rooms could possibly be UTP. g. Explain that an entrance facility is where connections from a corporate network to a third-party telecommunications provider are made, as well as WAN connections. 2. Teach students what tools are necessary to make UTP cables, as well as how to terminate at patch panels and punch down blocks. If possible, demonstrate how to make a UTP cable. Straight-Through Versus Crossover Cable 1. Explain when a straight-through cable should be used and when a crossover cable would be necessary. a. Generally, the rule is that connections between like devices (PC to PC, switch to switch) require crossover cables. b. Explain how MDI versus MDI-X affects cable choice. c. Students should be aware of the fact that quite a few devices automatically detect which wire pairs should be used, almost eliminating the need to worry about whether a crossover cable or straight-through cable should be used. d. Lastly, explain why two transmit and two receive wires are used. Teaching Tip There are other configurations for UTP cabling as well, such as the rollover cable (used for connecting to Cisco console ports). Quick Quiz 1 1. What is the process called that determines how bits are represented on the medium? Answer: encoding 2. What are the two types of interference often encountered when using copper media? Answer: electromagnetic interference (EMI) and radio frequency interference (RFI) 3. A __________ is a short cable for connecting a computer to an RJ-45 jack or connecting a patch-panel port to a switch or hub. Answer: patch cable 4. Horizontal wiring from the wall jack to the patch panel should be no longer than __________. Answer: 90 meters 5. Which category of UTP is the recommended cabling standard for 1 Gbps over copper media? a. CAT3 b. CAT4 c. CAT5 d. CAT6 Answer: CAT6 Fiber-Optic Cable 1. Describe how fiber-optic media works, and if possible, show a bundle of fiber to illustrate the composition of the media itself. Fiber-Optic Connectors 1. List the different types of fiber-optic connectors. a. Straight tip b. Straight connection c. Locking connection d. Medium interface connector e. Subminiature type A f. Mechanical transfer registered jack 2. Display a sizeable picture for each type if possible, and explain where each type is seen most commonly. Teaching Tip See the link for fiber-optic media types in the additional resources section for a look at the different kinds of connectors and a larger list of all the fiber connectors available. Fiber-Optic Installation 1. Explain the difficulty and cost involved with installing fiber, and then list some common equipment for fiber-optic termination. Fiber-Optic Cable Types 1. Describe the two main fiber cable types: single-mode fiber (SMF) cables and multimode fiber (MMF) cables. a. Explain the major distinction between these two types: SMF uses laser-based emitters while multimode uses lower-powered LED emitters. Teaching Tip As with any laser technology, stress the importance of proper safety procedures if using fiber-optic media. Students should NEVER look into a live fiber-optic media connector under any circumstance. Quick Quiz 2 1. True or False: Fiber-optic cable is immune to electromagnetic interference (EMI). Answer: True 2. A __________ fiber connector locks onto the jack when twisted. a. Locking connection (LC) b. Straight connection (SC) c. Straight tip (ST) d. Subminiature type A Answer: Straight tip (ST) 3. True or False: The connectors and test equipment required for fiber termination are considerably less expensive than their copper counterparts? Answer: False – more expensive 4. Name the two main types of fiber-optic cable. Answer: single-mode and multimode fiber 5. Which fiber-optic media type uses light-emitting diodes (LEDs) instead of lasers? a. Multimode fiber (MMF) b. Single mode fiber (SMF) c. Multicore fiber (MCF) d. Single core fiber (SCF) Answer: Multimode fiber Teaching Tip Students should be aware that fiber is susceptible to damage, and that because a break in the fiber-optic core would interrupt transmission they should be careful in routing fiber cabling. Sharp bends should be avoided. Wireless Networking 1. Detail why wireless has become so prevalent in the modern networking environment. Wireless Benefits 1. Cover some of the benefits of deploying a wireless network. a. Wireless can provide quick connections to existing wired networks without the need to run cable. b. Wireless networks also give end users some mobility 2. Describe some common usages of wireless technology by major corporations, hospitals, or delivery services. Teaching Tip Wireless has become a major selling point for the next generation of wireless devices: the smartphone. Most of these mobile devices have the ability to use mobile broadband services, but perhaps more interestingly, many of them now include internal wireless NICs to offset the costs of using mobile broadband. Types of Wireless Networks 1. List the different types of wireless networks. a. LANs b. Extended LANs c. Internet service d. Mobile computing 2. Detail how wireless works for each of the above types Wireless LAN Components 1. Break down wireless networks into their essential components, such as antennas and transmitters, the need for a transceiver, and how these components interact with each other. Wireless LAN Transmission 1. Describe the physical details behind how a wireless LAN works, detailing frequency communication and how it relates to speed of data transmission, as well as range. 2. List the four main technologies of wireless LANs: a. Infrared b. Laser c. Narrowband d. Spread-spectrum 3. Explain how infrared wireless networks function, and discuss advantages/disadvantages. Discuss the four main types: a. Line of sight b. Reflective c. Scatter d. Broadband optical telepoint 4. Explain how laser-based LAN technologies function, and discuss advantages/disadvantages. a. Requires line of sight b. Solid objects blocking a beam will interrupt transmissions 5. Explain how narrowband radio LAN technologies function, and discuss advantages/disadvantages. a. Highly susceptible to interference and eavesdropping b. Cost varies from moderate to very expensive depending on the technology used c. Encryption is almost a requirement due to the relative ease of listening in on communication 6. Explain how spread-spectrum LAN technologies function, and discuss advantages/disadvantages. Discuss the two main types: a. Frequency hopping b. Direct sequence modulation (used by 802.11b/g) c. Orthogonal frequency divisional multiplexing (used by 802.11a/g/n) 7. Explain how wireless extended LAN technologies function, and discuss advantages/disadvantages. a. An advantage would be the use of a wireless bridge to connect two remote LANs that are still relatively close to each other, but are prevented from wired connection by cost. 8. Explain how microwave networking technologies function, and discuss advantages/disadvantages. Discuss the two main types: a. Terrestial b. Satellite LAN Media Selection Criteria 1. Cover the different criteria for selecting LAN media. a. Bandwidth—How fast? b. Budget—How much money can you spend on cabling? Equipment? c. Environmental considerations—Are you in a high EMI environment? d. Span—Distances involved with cabling? e. Existing cable plant—If upgrading, is it worth changing media? 2. Weigh the benefits of choosing one type of media over another for distance, bandwidth, ease of installation, or cost. Quick Quiz 3 1. What is the name of the device that is used to translate between wired and wireless networks? Answer: transceiver or an access point 2. Name at least two of the four prime technologies wireless LANs use for transmitting and receiving data. Answer: infrared, laser, narrowband radio, and spread-spectrum radio 3. __________ can connect networks up to three miles. Answer: Wireless bridges 4. __________ systems send and receive data from geosynchronous satellites that maintain fixed positions in the sky. Answer: Satellite microwave 5. Which of the following is not a type of infrared LAN technology? a. Line-of-sight networks b. Reflective wireless networks c. Scatter infrared networks d. Laser networks Answer: Laser networks Class Discussion Topics 1. Get students to discuss how they might design a network given different situations. Namely, what would students do for a college campus with hundreds of staff users and students? How would they connect these buildings? Where would wireless technologies be deployed, if at all? 2. In the same vein as the above discussion, inquire how students might connect the first campus to a second campus nearby. Additional Projects 1. Have students research the different kinds of equipment available for fiber-optic termination. Higher-end mobile termination devices exist that use a laser to fuse together two separate strands of fiber-optic cable (check for videos on YouTube) with a screen that shows the process as it happens. While fascinating, this equipment is also very expensive. Additional Resources 1. See http://en.wikipedia.org/wiki/UTP_cable#History for a history of the twisted-pair cable. 2. Because there are a good number of fiber-optic connectors, you should send students to http://en.wikipedia.org/wiki/Optical_fiber_connector#Types to view the pictures of each type. You’ll also find a detailed list of all the different types. Key Terms attenuation The weakening of a signal as it travels the length of the media. backbone cabling Network cabling that interconnects TCs and equipment rooms. This cabling runs between floors or wings of a building and between buildings to carry network traffic destined for devices outside the work area. It’s frequently fiber-optic cable but can also be UTP. Also called vertical cabling. cable plant The collection of all the cables and connectors that tie a network together. cable segment A length of cable between two network devices, such as a NIC and a switch. Any intermediate passive (unpowered) devices, such as wall jacks, are considered part of the total segment length. crossover cable A type of patch cable that uses the 586B standard on one end and the 586A standard on the other end. This arrangement crosses the transmit and receive wires so that transmit on one end connects to receive on the other end. Often used to connect two devices of the same type to one another—for example, connecting a hub to a hub or a switch to a switch. crosstalk Interference one wire generates on another wire when both wires are in a bundle. data grade A grade of cable that is suitable for data networking. differential signal A method for transmitting data in which two wires of opposite polarity are used. One wire transmits using positive voltage and the other uses negative voltage. Differential signals enhance signal reliability by providing a canceling effect on EMI and crosstalk. electromagnetic interference (EMI) A disturbance to the operation of an electronic circuit or its data caused by devices that emit an electromagnetic field. encoding The method used to represent bits on the medium. entrance facility The location of the cabling and equipment that connects a corporate network to a third-party telecommunications provider. It can also serve as an equipment room and the main cross-connect for all backbone cabling. equipment room A room that houses servers, routers, switches, and other major network equipment and serves as a connection point for backbone cabling running between TCs. extended LANs A LAN that is expanded beyond its normal distance limitations by using wireless communication. fiber-optic cable A cable type that carries data over thin strands of glass using optical (light) pulses to represent bits. hertz (Hz) A unit that expresses how many times per second a signal or electromagnetic wave occurs. horizontal wiring The network cabling that runs from the work area’s wall jack to the telecommunications closet and is usually terminated at a patch panel. The total maximum distance for horizontal wiring is up to 100 meters. infrared (IR) A very long wavelength light source that is in the invisible spectrum and can be used to transmit data wirelessly. IrDA devices that use infrared signals to communicate. IrDA stands for Infrared Device Association. MDI crossed (MDI-X) devices Network devices that connect by using RJ-45 plugs over twisted-pair cabling. MDI-X devices transmit over pins 3 and 6 and receive over pins 1 and 2 of the RJ-45 connector. medium dependent interface (MDI) devices Network devices that connect by using RJ-45 plugs over twisted-pair cabling. MDI devices transmit on pins 1 and 2 and receive on pins 3 and 6 of the RJ-45 connector. narrowband radio Low-powered, two-way radio communication systems, such as those used in taxis, police radios, and other private radio systems. Also called single-frequency radio. patch cable A short cable for connecting a computer to an RJ-45 jack or connecting a patch-panel port to a switch or hub. Also see straight-through cable. radio frequency interference (RFI) Similar to EMI, except that RFI is usually interference caused by strong broadcast sources. See also EMI. RJ-45 jack Used in the work area in wall plates and surface-mount boxes to plug a patch cable that connects a computer to the horizontal cable. RJ-45 plug The connector used to terminate twisted-pair cable for making patch cables. It has eight wire traces to accommodate a standard twisted-pair cable with four wire pairs. satellite microwave Micro wave communication systems that send and receive data from satellites that maintain fixed positions in the sky. spread-spectrum radio Uses multiple frequencies simultaneously, thereby improving reliability and reducing susceptibility to interference over narrowband radio. straight-through cable A standard patch cable that uses the same wiring standards on both ends of the cable so that each wire is in the same corresponding location on both ends of the cable (pin 1 goes to pin 1, pin 2 to pin 2, and so forth). Also see patch cable. structured cabling A specification of how cabling should be organized in data and voice networks, regardless of the media type or network architecture. telecommunications closet (TC) Usually an enclosed space or room that provides connectivity to computer equipment in the nearby work area. In small installations, it can also serve as the entrance facility. Typical equipment includes patch panels to terminate horizontal wiring runs, hubs, and switches. termination The attachment of RJ-45 plugs on a cable to make a patch cable or punching down the cable wires into terminal blocks on a jack or patch panel. terrestrial microwave Line-of-sight transmissions between microwave towers or between transmitters and receivers mounted on tall buildings, mountaintops, or other locations with long, clear lines of sight. transceiver A device that transmits and receives. In wireless networking, an access point is a transceiver. twisted-pair (TP) cable One or more pairs of insulated strands of copper wire twisted around one another and housed in an outer jacket or sheath. voice grade A grade of cable that is not suitable for data networking, but is suitable for voice communication. wireless bridge A wireless network arrangement that connects networks up to three miles (4.4 km) apart, permitting locations to be linked by using line-of-sight or broadcast transmissions. work area The location of workstations and other user device—in short, the place where people work with computers and other network devices. Technical Notes for Hands-On Projects All projects in this book that use the Sharing and Security option for folders assume that the Use simple file sharing option has been disabled. Hands-On Project 4-1: This project requires a wire cutter and cable stripper, RJ-45 crimping tool, 2 to 4 feet of Cat 5/5e or Cat 6 cable, two RJ-45 plugs, cable tester (optional). Hands-On Project 4-2: This project requires a wire cutter and cable stripper, 2 to 4 feet of Cat 5/5e or Cat 6 cable, a 110 punch down tool, a Cat 5/5E or Cat 6 patch panel (a 568A or 568B patch panel can be used; 568B panels are more common), RJ-45 jack, cable tester (optional). Hands-On Project 4-3: This project requires the patch cable you made, an additional patch cable, the patch panel and RJ-45 jack to which you terminated the cable, a PC, and a hub or switch. Chapter 5 Network Protocols At a Glance Instructor’s Manual Table of Contents • Overview • Objectives • Teaching Tips • Quick Quizzes • Class Discussion Topics • Additional Projects • Additional Resources • Key Terms • Technical Notes for Hands-On Projects • Using Virtualization for Hands-On Projects Lecture Notes Overview Chapter 5 will introduce students to the purpose of network protocols. They also learn the layers in the TCP/IP architecture and the protocols found in each layer. At the end of the chapter, students will learn about IP configuration and fundamentals of subnetting. Objectives • Describe the purpose of a network protocol, the layers in the TCP/IP architecture, and the protocols in each TCP/IP layer • Explain IP address configuration and subnetting Teaching Tips TCP/IP’s Layered Architecture 1. Discuss what protocols are and how protocol suites or protocol stacks are formed. 2. Use the most common protocol suite, TCP/IP, as an example. 3. Illustrate the TCP/IP model, and point out what protocols exist at what layer in the model. Role of the Network Access Layer 1. Explain the tasks that the network access layer performs, such as a. Providing a physical MAC address for the network interface b. Transmits and receives bit signals c. Defines the media and connectors needed to make a physical network connection Role of the Internetwork Layer 1. Explain the role of the internetwork layer and how it encompasses the heart of the TCP/IP suite. a. Students should know that the internetwork layer is where IP addresses are found and that every IP address contains two parts: a network ID and a host ID. b. Describe to students the process by which the internetwork layer is responsible for routing packets from network to network until they reach their destination. c. This is also where MAC addresses are resolved from IP addresses using the ARP resolution protocol. d. Discuss the responsibility of the internetwork layer protocols in efficient delivery of packets. In that same vein, define what a connectionless protocol is and how it contrasts to a connection-oriented protocol for reliable delivery. Protocols at the Internetwork Layer 1. List the protocols used at the internetwork layer prior to describing the purpose of each one: a. Internet Protocol Version 4 (IPv4) is a connectionless protocol and is the most commonly used network protocol. It uses a dotted decimal address separated into 4 octets used to describe a binary address 32 bits long. Briefly explain some of the parts of an IP packet header and their purpose. b. Internet Protocol Version 6 (IPv6) is the successor to the IPv4 protocol and has addresses that are 128 bits long. Students must know that IPv4’s biggest flaw is limited address space, which IPv6 is largely designed to fix. c. Detail the use of the Address Resolution Protocol to resolve a logical IP address to a physical MAC address. d. Talk about the Internet Control Message Protocol (ICMP) and its use as a troubleshooting method for connectivity. Also expand on this by listing the utilities that make use of ICMP, such as ping and tracert. e. Explain IPSec and its use as a means to secure delivery of packets by using authentication and encryption. Teaching Tip Have students review Simulation 9: The Changing Frame Header on the book’s CD. Role of the Transport Layer 1. Describe the role of the transport layer for handling reliability of packet delivery as well as the use of connectionless protocols to ensure efficient communication. 2. The two main protocols to discuss at this layer are TCP and UDP. 3. Explain to students that the transport layer works with units of data called segments. These segments are then passed down to an internetwork layer protocol, such as IP. 4. Describe how port numbers identify application destinations for TCP and UDP and how these port numbers can be used to identify what services might be running on a computer. For example, a computer with port 80 open suggests a Web service might respond to HTTP GET requests. 5. Show students how UDP and TCP both protect data integrity by adding a checksum to communications. a. This does not make UDP a reliable protocol, it simply means that it can detect whether a packet was received correctly. In this way, the checksum acts similar to the CRC added to frames. TCP: The Reliable Transport Layer 1. Explain to students that applications can use TCP for reliable packet delivery. This works by: a. Establishing a connection b. Segmenting large chunks of data c. Ensuring flow control with acknowledgments 2. Describe the handshaking process for TCP and how syn, ack-syn, ack, and rest segments are used to facilitate the three-way handshake. 3. Explain how TCP breaks up large amounts of data into segments in order to meet the requirement that everything fit into 1518 bytes per frame. Also, cover how TCP handles segments that arrive out of order by using sequence numbers. 4. Show TCP’s use of flow control to prevent a destination from becoming overwhelmed by data. This is done by establishing a sliding window size that can be expanded or shrunk. Role of the Application Layer 1. Describe the purpose of the application layer and its role in providing network services to user applications. Give examples of protocols that work at the application layer to provide these services, such as HTTP. 2. Make students aware of the fact that most application layer protocols have a client and a server set up. 3. Explain that HTTP is the protocol used by Web browsers to access Web pages. Originally used for transferring HTML pages, it can now be used for file transfer as well. 4. Talk about the e-mail protocols available at the application layer: POP, IMAP, and SMTP. Explain the benefits inherent in IMAP versus POP, and describe how SMTP sends mail across the Internet. 5. Dynamic Host Configuration Protocol (DHCP) should be discussed as a means to assign IP addresses to hosts dynamically instead of statically. a. Describe the steps in leasing or renewing a lease on an IP address with DHCP. b. Explain what can occur if DHCP servers aren’t available and a host is configured to use dynamic address assignment. With Windows, these hosts may assign themselves an APIPA (Automatic Private IP Addressing) address, which starts with 169.254. 6. Explain DNS as a means to resolve easy-to-remember domain names into IP addresses and how the top-level domains are organized. a. Describe the process by which an administrator sets up a DNS server, and the creation of host records. Teaching Tip If students have had previous computer courses, they may benefit from a comparison of DNS to a database, or even as a hierarchical file system. Top-level domains would be considered root folders, with individual domain names being represented as folders deeper into the structure. This can help to explain how DNS is structured. Quick Quiz 1 1. When a set of protocols works together cooperatively it is known as a __________. Answer: protocol stack or protocol suite 2. At what layer of the TCP/IP suite are IP addresses defined and verified? Answer: internetwork layer 3. When using a __________, no lasting connection is made from source to destination. Answer: connectionless protocol 4. TCP and UDP use __________ to specify the source and destination application-layer protocols. a. Segment numbers b. Window size headers c. Port numbers d. IP addresses Answer: port numbers 5. What port is associated with the DNS service? a. 54 b. 63 c. 80 d. 53 Answer: 53 IP Addressing 1. Explain how IP addresses are formatted and how the network address for a given IP is determined. IP Address Classes 1. Show students the different classes of IP addresses, and describe how to determine what class an IP address is. a. Class A: 1 – 127 b. Class B: 128 – 191 c. Class C: 192 – 223 d. Class D: 224 – 239 e. Class E: 240 – 255 2. Explain the use of the entire 127.0.0.0 A class network for loopback purposes. Teaching Tip Despite what looks to be a large range of addresses available for IPv4, some have estimated that we will be completely out of IPv4 address blocks in late 2010/early 2011. Private IP Addresses 1. Illustrate the need for private IP addresses, and discuss how IPv4’s addressing limitations have affected the use of private IP addressing. Network Address Translation 1. Explain how Network Address Translation allows the deployment of private IP addressing behind a public IP address or addresses. a. Port Address Translation extends NAT by allowing many private IP-addressed machines to use a single public IP address or several IP addresses from a pool. Teaching Tip Have students review Simulation 10: Demonstrating NAT/PAT on the book’s CD. Classless Interdomain Routing 1. Discuss how Classless Interdomain Routing has improved the flexibility of IPv4 addressing versus the use of classful addressing. Explain the use of an IP prefix in CIDR notation. Subnet Masks 1. Students should understand that the subnet mask is how devices figure out what part of an IP address is used for network information and which part is used for host addressing. a. Subnets have the same format as an IP address 2. Explain how the subnet mask is used to find other remote networks. 3. Explain why a default gateway must be within the same subnet as a PC attempting to use it. 4. Discuss the reasons for subnetting a network, either for organization or for separating broadcast domains, or more efficient use of addresses. Binary Arithmetic 1. Teach how to express values using binary arithmetic, which uses powers of two. Give several examples of converting a decimal number to its binary equivalent. If possible, give some tricks to help ensure students can do this rather quickly. Calculating a Subnet Mask 1. Describe how to subnet with the purpose of creating more networks or with the purpose of creating more hosts. a. Teach students to first figure out how many bits will be needed to accommodate whatever they’re trying to work with. For example, 120 hosts would require 7 bits (2^7 = 128). b. Explain how to reallocate these bits to accommodate for these hosts. The intent in 1-a is presumably to only provide for those 120 hosts, while simultaneously creating some additional networks. If a class C address was used, say 192.168.1.0, the subnet mask would become 255.255.255.128. This would create two subnets on the class C: 192.168.1.0 and 192.168.1.128. c. Students must be aware of the formula 2^n-2 when subnetting. Super netting 1. Explain what super netting is and how it is most commonly used for summarizing routes in route tables. a. Super netting is essentially the reverse operation of subnetting. Introduction to Internet Protocol Version 6 1. Clarify the reasons why IPv6 has become IPv4’s successor. Show some of the features that address IPv4’s biggest shortcomings. a. Discuss features like built-in QoS and IPSec. b. Also discuss the two types of autoconfiguration available for IPv6: stateless and stateful. 2. Show an example of an IPv6 address and the various ways that can be used to shorthand an IPv6 address. 3. Students need a basic understanding of how hexadecimal notation works. 4. Describe the various parts of the average IPv6 address, namely which portions are host bits and which are MAC address based. 5. Although subnetting is not something the average administrator will have to do with IPv6, students should be aware that subnetting has not completely gone away with IPv6. Quick Quiz 2 1. Which of the five IP address class ranges are available for host assignment? Answer: Classes A, B, and C. 2. __________ allows an organization to use private IP addresses while connected to the Internet. Answer: Network Address Translation (NAT) 3. What is the name of the process of dividing a single network address into two or more subnetwork addresses, each with fewer available host IDs than the original network address. Answer: subnetting 4. An IPv6 address is __________ rather than the 32 bits in an IPv4 address. a. 64 bits b. 96 bits c. 112 bits d. 128 bits Answer: 128 bits 5. What subnet does the following network in CIDR notation have? 192.168.2.0/27 a. 255.255.255.224 b. 255.255.255.192 c. 255.255.255.240 d. 255.255.255.128 Answer: 255.255.255.224 Class Discussion Topics 1. Have students research some of the different protocols used at each layer of the TCP/IP model, and then discuss their findings with each other. Make sure students can make relatively good guesses as to what protocols belong at what layers. Additional Projects 1. Students can research what options administrators currently have to slow the depletion of IPv4 addresses available. Ask students what technologies they’d use to assist in migration. Additional Resources 1. http://www.iana.org/assignments/ipv4-address-space/ipv4-address-space.txt shows the current allocation of IPv4 blocks. 2. http://www.subnet-calculator.com/ is an online tool for helping students with subnetting questions. Key Terms Address Resolution Protocol (ARP) An internetwork layer protocol that is used to resolve a host’s IP address to its MAC address. ARP uses a broadcast frame containing the IP address of the target host and the host that is assigned the address responds with its MAC address. address space The number of addresses available in an IP network number that can be used to assign to hosts. ARP cache A temporary storage location in an IP host’s RAM that stores recently learned IP address/MAC address pairs so the ARP protocol is not necessary for each packet sent to a host. Automatic Private IP Addressing (APIPA) A private range of IP addresses that are automatically assigned to an APIPA-enabled computer when an IP address is requested via DHCP but no DHCP server responds to the request. Classless Interdomain Routing (CIDR) A method of IP addressing in which the network and host IDs are determined by a prefix number that specifies how many bits of the IP address are network bits while the remaining are host bits. connectionless protocol A type of network communication in which data is transferred without a connection first being made between communicating devices and no acknowledgment that the data was received is given by the receiving station. Domain Name System (DNS) An application layer protocol that resolves computer and domain names to their IP address. DNS uses the UDP transport protocol. dotted decimal notation The format used to express an IPv4 address—four decimal numbers separated by periods. Dynamic Host Configuration Protocol (DHCP) An application layer protocol used to dynamically configure a host’s IP address settings. DHCP uses the UDP transport protocol because DHCP messages consist of a single packet and are used on the local LAN. flow control A mechanism used by network protocols to prevent a destination device from becoming overwhelmed by data from a transmitting computer, resulting in dropped packets. fully qualified domain name (FQDN) A name that includes the host name, subdomain names (if applicable), second-level domain name, and top-level domain name separated by a period. Internet Control Message Protocol (ICMP) An internetwork layer protocol used to send error and control messages between systems or devices. It’s an encapsulated IP protocol, meaning it’s wrapped in an IP header. Internet Message Access Protocol (IMAP) An application layer protocol used by a client e-mail application to download awaiting messages from an e-mail server. Operates on TCP port 143. IMAP provides fault-tolerant features and only downloads message headers from the server initially and downloads the body of the message and attachments if the message is selected. Internet Protocol Security (IPSec) An extension to IP that provides security by using authentication and encryption. It authenticates the identity of computers transmitting data with a password or some other form of credentials, and it encrypts data so that if packets are captured, the data will be unintelligible. Internet Protocol version 4 (IPv4) A connectionless internetwork-layer protocol that provides source and destination addressing and routing for the TCP/IP suite. Uses 32-bit dotted decimal addresses. Internet Protocol version 6 (IPv6) A connectionless internetwork layer protocol that provides source and destination addressing and routing for the TCP/IP suite. Uses 128-bit hexadecimal addresses, plus has built-in security and QoS features. IP address A 32-bit dotted-decimal address used by the IP to determine the network a host resides on and to identify individual hosts on the network at the internetwork layer. IP prefix A value used to express how many bits of an IP address are network ID bits. Usually expressed as /prefix-number. For example, 192.168.1.24/27 in which 27 is the IP prefix or simply prefix. localhost The name used to refer to the loopback address in an IP network. See also loopback address. loopback address An address that always refers to the local computer—in IPv4, 127.0.0.1 is the loopback address. Network Address Translation (NAT) A device that translates a private IP address to a public IP address in packets that are destined for the Internet and then translates the public IP address in the reply back to the private address. octet A grouping of 8 bits, often used to identify the four 8-bit decimal numbers that compose an IP address. For example: first octet, second octet, and so forth. Port Address Translation (PAT) An extension of NAT, PAT allows several hundred workstations to access the Internet with a single public Internet address by using transport layer port numbers to differentiate each host conversation. port number A field in the transport layer protocol header that specifies the source and destination application-layer protocols that are used to request data and are the target of the request, respectively. Post Office Protocol version 3 (POP3) An application layer protocol used by a client e-mail application to download awaiting messages from an e-mail server. Operates on TCP port 110. protocol Rules and procedures for communication and behavior. Computers must use a common protocol and agree on the rules of communication. protocol stack A set of protocols that works cooperatively to provide network communication. Protocols are ‘stacked’ in layers in which each layer performs a unique function required for successful communication. Also called a protocol suite. protocol suite See protocol stack. quality of service (QoS) Describes a network’s capability to prioritize data packets based on the type of information they contain (for example, voice, video, or file data) or urgency of the information. segment The unit of information used by the transport layer. A segment is passed up to the application layer as data and it is passed down to the internetwork layer where it becomes a packet. Simple Mail Transfer Protocol (SMTP) The standard protocol for sending e-mail over the Internet. subnet A subdivision of an IP network address space. subnet mask A 32-bit number in dotted decimal format consisting of a string of eight or more binary 1s followed by a string of 0s. Determines which part of an IP address is the network ID and which part is the host ID. A binary 1 in the subnet mask signifies that the corresponding bit in the IP address belongs to the network address, and a binary 0 signifies that the corresponding bit in the IP address belongs to the host ID. subnetting The process of dividing a single IP network address into two or more subnetwork addresses. See also subnet. super netting Reallocation of bits from the network portion of an IP address to the host portion, effectively making two or more smaller subnets a larger superset. three-way handshake A series of three packets used between a client and server to create a TCP connection. Once the three-way handshake is completed successfully, a connection is established between a client and server application and data can be transferred. Transmission Control Protocol (TCP) A transport layer protocol that is connection oriented and designed for reliable transfer of information in complex internetworks. Transmission Control Protocol/Internet Protocol (TCP/IP) The most common protocol suite/protocol stack in use. TCP/IP is the default protocol in contemporary OSs and the protocol of the Internet. User Datagram Protocol (UDP) A connectionless transport layer protocol designed for efficient communication of generally small amounts of data. Technical Notes for Hands-On Projects All projects in this book that use the Sharing and Security option for folders assume that the Use simple file sharing option has been disabled. Hands-On Project 5-1: This project requires a classroom computer. Hands-On Project 5-2: This project requires a classroom computer with Wireshark installed. Hands-On Project 5-3: This project requires a classroom computer with Wireshark installed. Hands-On Project 5-4: This project requires a classroom computer with Wireshark installed. Hands-On Project 5-5: This project requires a classroom computer. Hands-On Project 5-6: This project requires a classroom computer. Hands-On Project 5-7: This project requires a classroom computer. Hands-On Project 5-8: This project requires a classroom computer. Challenge Lab 5-1: This project requires a classroom computer. Challenge Lab 5-2: This project requires a classroom computer. Using Virtualization for Hands-On Projects The following Hands-On Projects/Challenge Labs have been identified as those that students can do using virtual machines rather than physical machines. Hands-On Project 5-1 Hands-On Project 5-2 Hands-On Project 5-3 Hands-On Project 5-4 Hands-On Project 5-5 Hands-On Project 5-6 Hands-On Project 5-7 Hands-On Project 5-8 Challenge Lab 5-1 Challenge Lab 5-2 Chapter 6 Network Reference Models and Standards At a Glance Instructor’s Manual Table of Contents • Overview • Objectives • Teaching Tips • Quick Quizzes • Class Discussion Topics • Additional Projects • Additional Resources • Key Terms • Technical Notes for Hands-On Projects • Using Virtualization for Hands-On Projects Lecture Notes Overview Chapter 6 will introduce students to the OSI reference model layers and how they relate to hardware and software. They will also learn about the IEEE 802 networking model and the importance of standards in networking. Objectives • Explain the OSI reference model layers and their relationship to hardware and software • Explain the IEEE 802 networking model and related standards Teaching Tips Introducing the OSI and IEEE 802 Networking Models 1. Explain to students why the OSI model has become such a key part of networking. 2. Make students aware of the need for standardization and how it helps to ensure devices from different manufacturers will work together. Role of a Reference Model 1. Show students why there is a need for a reference model, and what having a reference model does for reducing the complexity of troubleshooting issues. 2. Explain how the reference model also allows for additional flexibility when protocols are changed, such as the case for changing IPv4 to IPv6. For the most part, changing a network layer protocol has little to no effect on the other layers. Structure of the OSI Model 1. Detail the seven layers of the OSI model: a. Application b. Presentation c. Session d. Transport e. Network f. Data Link g. Physical 2. Once you’ve shown students the OSI model, compare it to the TCP/IP model, and show which layers on the OSI model match up with layers on the TCP/IP model. 3. Explain what is meant by peer communication and how layers interact between two separate communicating devices. 4. Define what a protocol data unit is and how the PDU changes at different layers. 5. Describe the process of encapsulation/de-encapsulation. a. Compare this to a similar physical process that they’re familiar with, such as packaging (encapsulating) an object to prepare it for shipping. Teaching Tip Have students review Simulation 11: Peer Communication with the OSI Model. Application Layer 1. Detail the services and functionality available at the application layer, such as file sharing, HTTP, FTP, and SMTP for mail. Explain possible issues that can occur at this layer, such as misconfigured client software. Presentation Layer 1. Illustrate the functions at the presentation layer, where data is converted for the application layer when receiving data, or converted for the transport layer when sending. Session Layer 1. Describe how the session layer handles communication setup and teardown, and handles ongoing conversations. List some of the protocols that function at this layer, such as DNS. Transport Layer 1. Show students how the transport layer creates segments out of large data chunks, so that transmission will fit into the maximum transmission unit size for the network. a. Illustrate this by having students pretend to segment data out of a text file as if they were performing the actions of the transport layer manually. 2. Discuss the key elements of the transport layer header: a. Source and destination port numbers b. Sequence and acknowledgment numbers c. Window size 3. Discuss some of the issues that can occur at the transport layer, such as oversized segments or SYN attacks. Network Layer 1. Describe the purpose of the network layer and its role in handling logical addressing and routing. 2. Students should know the PDU at this layer is a packet. 3. Teach students the issues that can occur at the network layer, such as IP addresses being assigned incorrectly or routing issues. 4. List some of the hardware devices that function at the network level, such as routers, firewalls, VPN servers, and even layer 3 switches. 5. The network layer has the ability to perform access control; students should see an example of an access control list where IP addresses are blocked/allowed. This allows devices such as routers to act very much like a firewall. Data Link Layer 1. Show students how the data link layer interacts with frames and acts as the intermediary between the logical network layer and the physical layer. 2. Emphasize that the frame is the PDU for this layer. 3. Explain how the Frame Check Sequence (FCS) makes use of the CRC error-checking code. a. Make sure to remind students that this does not provide any kind of reliability. This is simply done so that bad frames can be thrown out. 4. Describe the process a frame goes through as it reaches each device. For example, what happens when a frame, destined for another network, reaches a router? 5. List the devices that function primarily at the data link layer, such as switches. Teaching Tip Have students review Simulation 9: The Changing Frame Header, to help recall the details of the last chapter Physical Layer 1. Break down the process of encoding bits into signals for passing over whatever media might be in use. 2. Discuss some of the hardware components that function at this layer, such as the cables and connectors for the media. 3. Detail some problems that happen at the physical layer, such as EMI or failed NICs. Summary of the OSI Model 1. Give a summary of what processes or primary functions occur at each level of the OSI model. Follow up with a reminder of the PDUs at each layer. 2. Show where networking devices function: a. Routers at the network layer b. Switches at the data link layer c. NICs at the physical layer 3. List common protocols that function on a given layer, such as DNS for session, DHCP for application, and IP for network. Teaching Tip For a much more in-depth look at the OSI model, download http://standards.iso.org/ittf/PubliclyAvailableStandards/s020269_ISO_IEC_7498-1_1994(E).zip , which contains the OSI document describing the OSI model. Quick Quiz 1 1. Why has the OSI Reference Model become such a key part of networking? Answer: It provides a common framework for developers and students of networking to work with and learn from. 2. What is meant by peer communication between layers? Answer: Each layer on the receiving computer sees network data in the same format its counterpart on the sending computer did. 3. Which layer permits two computers to hold ongoing communications across a network, so applications on either end of the session can exchange data for as long as the session lasts? Answer: session layer 4. The segmenting of the data is important because every network technology has a maximum frame size called the __________. a. Maximum Frame Unit b. Maximum Packet Unit c. Maximum Byte Unit d. Maximum Segment Unit Answer: Maximum Transmission Unit (MTU) 5. What PDU is in use at the Transport layer of the OSI model? a. Packet b. Frame c. Bit d. Segment Answer: Segment IEEE 802 Networking Standards 1. Discuss the origin of IEEE and the 802 project. IEEE 802 Specifications 1. Detail some of the most important and widely used standards, as well as some historical standards that have helped to define newer ones. a. 802.3 for Ethernet LAN b. 802.5 for Token Ring LAN c. 802.16 for wireless metropolitan area networks (WiMAX) Teaching Tip For a list of IEEE standards and links to packages describing each one, visit http://en.wikipedia.org/wiki/IEEE_802. IEEE 802 Extensions to the OSI Reference Model 1. Describe the extensions to the OSI reference model, and how they are used. a. Students must learn that the logical link control sublayer handles error recovery and flow control. b. They should also know about the media access control sublayer, which manages access to the physical medium. This sublayer is the reason why NICs have MAC addresses, as defined by 802.2 Quick Quiz 2 1. Why did the IEEE feel the need to develop LAN standards? Answer: To ensure that network interfaces and cabling from multiple manufacturers would be compatible. 2. In the IEEE 802 standards, each number after the dot represents a different __________. a. year the standard was drafted b. year the standard was revised c. technology or subset of a technology d. subset of another standard Answer: technology or subset of a technology 3. What are the names of the two sublayers of the data link layer? a. logical media control and media link control b. physical media control and media access control c. logical link control and media transmission control d. logical link control and media access control Answer: logical link control (LLC) and media access control (MAC) 4. Which sublayer defines the use of logical interface points, called Service Access Points (SAPs)? Answer: LLC 5. Which 802 standard describes Token Ring? a. 802.2 b. 802.5 c. 802.16 d. 802.22 Answer: 802.5 Class Discussion Topics 1. Have the class discuss what technologies or common problems would fall under a certain OSI layer. Because Administrators commonly refer to a “___ layer issue”, it is important that students be able to identify what issues a layer might have. Additional Projects 1. Get students to act out a transmission as if each student was a layer of the OSI model, using some sort of prop. For example, if a student was sending a transmission, you could have him put a letter into an envelope for the network layer. He could then hand the envelope to another student pretending to be the data link layer, which would involve him placing the envelope in a larger package (frame) prior to giving it to the next student. Additional Resources 1. http://standards.ieee.org/about/get/ 2. http://en.wikipedia.org/wiki/OSI_model Key Terms IEEE 802.3 Network specification that covers all forms of Ethernet media and interfaces, from 10 Mbps to 10 Gbps (10 Gigabit Ethernet). IEEE 802.11 Network specification that sets standards for wireless networking in LANs for many different broadcast frequencies and techniques. IEEE 802.15 Covers standards for wireless personal area networks. IEEE 802.16 Covers wireless metropolitan area networks. access control In the context of the network layer and routing, the process by which a router consults a list of rules before forwarding an incoming packet. The rules determine whether a packet meeting certain criteria (such as source and destination address) should be permitted to reach the intended destination. application layer Layer 7 in the OSI model provides interfaces that enable applications to request and receive network services. See also Open Systems Interconnection (OSI) reference model. data link layer Layer 2 in the OSI model is responsible for managing access to the network medium and delivery of data frames from sender to receiver or sender to intermediate device such as a router. See also Open Systems Interconnection (OSI) reference model. de-encapsulation The process of stripping the header from a PDU as it makes its way up the communication layers before being passed to the next higher layer. See also protocol data unit (PDU). encapsulation The process of adding the header to a PDU as it makes its way down the communication layers before being passed to the next lower layer. See also protocol data unit (PDU). encoding Representing 0s and 1s as a physical signal, such as electrical voltage or a light pulse. International Organization for Standardization (ISO) The international standards-setting body based in Geneva, Switzerland, that sets worldwide technology standards. logical link control (LLC) sublayer The upper sublayer of the IEEE Project 802 model for the OSI model’s data link layer. It handles error-free delivery and controls the flow of frames between sender and receiver across a network. maximum transmission unit (MTU) The maximum frame size allowed to be transmitted across the media. media access control (MAC) sublayer The lower sublayer of the IEEE Project 802 model for the OSI model’s data link layer. It handles accessing network media and mapping between logical and physical network addresses for NICs. network layer Layer 3 of the OSI model handles logical addressing and routing of PDUs across internetworks. See also Open Systems Interconnection (OSI) reference model and protocol data unit (PDU). Open Systems Interconnection (OSI) reference model ISO Standard 7498 defines a frame of reference for understanding networks by dividing the process of network communication into seven layers. Each layer is defined in terms of the services and data it handles on behalf of the layer above it and the services and data it needs from the layer below it. peer communication In the layered approach, each layer on one computer behaves as though it were communicating with its counterpart on the other computer. This means each layer on the receiving computer sees network data in the same format its counterpart on the sending computer did. physical layer Layer 1, the bottom layer of the OSI model, transmits and receives signals and specifies the physical details of cables, adapter cards, connectors, and hardware behavior. See also Open Systems Interconnection (OSI) reference model. presentation layer At Layer 6 of the OSI model, data can be encrypted and/or compressed to facilitate delivery. Platform-specific application formats are translated into generic data formats for transmission or from generic data formats into platform-specific application formats for delivery to the application layer. See also Open Systems Interconnection (OSI) reference model. protocol data unit (PDU) A unit of information passed as a self-contained data structure from one layer to another on its way up or down the network protocol stack. session layer Layer 5 of the OSI model is responsible for setting up, maintaining, and ending communication sequences (called sessions) across a network. See also Open Systems Interconnection (OSI) reference model. transport layer Layer 4 of the OSI model is responsible for reliable delivery of data streams across a network. Layer 4 protocols break large streams of data into smaller chunks and uses sequence numbers and acknowledgments to provide communication and flow control. See also Open Systems Interconnection (OSI) reference model and protocol data unit (PDU). Technical Notes for Hands-On Projects All projects in this book that use the Sharing and Security option for folders assume that the Use simple file sharing option has been disabled. Hands-On Project 6-1: This project requires a classroom computer. Hands-On Project 6-2: This project requires a classroom computer and Simulation 12 on the book’s CD. Hands-On Project 6-3: This project requires a classroom computer and Simulation 13 on the book’s CD. Hands-On Project 6-4: This project requires a classroom computer and Simulation 14 on the book’s CD. Using Virtualization for Hands-On Projects The following Hands-On Projects/Challenge Labs have been identified as those that students can do using virtual machines rather than physical machines. Hands-On Project 6-1 Hands-On Project 6-2 Hands-On Project 6-3 Hands-On Project 6-4 Challenge Lab 6-1 Challenge Lab 6-2 Chapter 7 Network Hardware in Depth At a Glance Instructor’s Manual Table of Contents • Overview • Objectives • Teaching Tips • Quick Quizzes • Class Discussion Topics • Additional Projects • Additional Resources • Key Terms • Technical Notes for Hands-On Projects • Using Virtualization for Hands-On Projects Lecture Notes Overview Chapter 7 will introduce students to advanced features and operation of network switches. They also learn the characteristics of common routing protocols and how routing tables are created. Students will also learn about basic and advanced features of wireless access points. Finally, at the end of the chapter, students will be able to determine the best type of NIC to purchase for a computer. Objectives • Describe the advanced features and operation of network switches • Describe routing table properties and discuss routing protocols • Explain basic and advanced wireless access point features • Select the most suitable NIC bus and features for a computer Teaching Tips Network Switches in Depth 1. Briefly review some of the basics of what a switch does, how it handles broadcast traffic, and how it separates collision domains. Switch Port Modes of Operation 1. List the modes of operation available for switches, and discuss how auto-negotiate and auto-MDIX (automatic cable type sensing) affect these modes. Modes available: a. 10 Mbps half-duplex b. 100 Mbps half-duplex c. 10 Mbps full-duplex d. 100 Mbps full-duplex Creating the Switching Table 1. Explain how the switching table learns new MAC addresses, and how many switches can learn more than one MAC address off a single port. 2. Discuss aging time, which removes MAC addresses from the table after a certain amount of time. Frame Forwarding Methods 1. List the different methods available for switches to forward frames, and compare these methods to each other. Which method is more valuable for a given situation? a. Cut-through switching, designed to quickly forward frames, can end up forwarding damaged frames. b. Store and forward switching conserves bandwidth by checking the entire frame prior to forwarding. c. Fragment-free switching ensures that any frame forwarded is not a fragment and is the right size for the network type. Advanced Switch Features 1. Explain the difference between managed switches and smart switches, and what advantages one has over the other. Give some common features of smart switches, such as: a. Multicast b. Spanning Tree Protocol c. VLANs d. Port Security 2. Give students an understanding of what a multicast frame is, and give an example of a technology that commonly uses multicast, such as hard drive imaging solutions. a. Explain how switches process these multicast frames, either by treating them as broadcasts or by forwarding them to registered multicast addresses. 3. Describe the purpose for Spanning Tree Protocol, and explain how it works. a. Students should know what a broadcast storm is and how one can occur in a switched network. b. Go over some of the different modes of STP, such as blocking mode and forwarding mode. c. List some of the disadvantages of STP, and then weigh those disadvantages against not using STP. Students should identify that while STP may slow down initial link start time, it is a small price to pay for a loop-free switch network. 4. Introduce the idea of Virtual Local Area Networks, or VLANs. Explain the benefits of creating VLANs, such as the creation of broadcast domains or the ability to logically group switch ports. a. Talk about the main requirement for inter-VLAN communication: the router. 5. After having discussed how a router works with a VLAN, move on to talking about VLAN trunks, and how they reduce the amount of interfaces needed on a router to support VLANs on a switch. 6. Explain the pitfalls of using too many VLANs. Overuse of VLANs can turn what should be a simple network design into a complex and messy network that is difficult to troubleshoot. 7. Describe the port security feature’s ability to lock down ports so that they can only be used by specific machines with specific MAC addresses. a. Give examples of where this would be useful, such as locking down a network so that employees can’t bring in a SOHO router to the network and plug it in undetected (a very common occurrence). Teaching Tip Have students review Simulation 15: STP Prevents Switching Loops on the book’s CD. Teaching Tip Students should also review Simulation 16: How Switches Use Trunk Ports with VLANs. Quick Quiz 1 1. At what layer of the OSI model do switches operate? Answer: data link layer 2. When a switch attempts to set a port’s operating mode to the highest performance setting, the connecting device that supports it is called __________? Answer: auto-negotiate mode 3. Which frame forwarding method requires that the switch read the entire frame into its buffers before forwarding it? Answer: store-and-forward switching 4. Switches that support __________ enable you to configure one or more switch ports into separate broadcast domains. a. multicast b. Spanning Tree Protocol c. VLANs d. port security Answer: virtual local area networks (VLANs) 5. When would a switch in fragment-free switching mode determine that a frame on an Ethernet network is bad? a. Frame size < 16 bytes b. Frame size < 32 bytes c. Frame size < 48 bytes d. Frame size < 64 bytes Answer: Frame size < 64 bytes Routers in Depth 1. Review how routers function, and what roles and services they provide to networks. a. Students should know that routers are not just used to connect to the Internet as gateways; they’re also used in internetworks for large organizations to provide path redundancy. 2. List the features of a router that affect processing of packets: a. Router interfaces b. Routing tables c. Routing protocols d. Access control lists Router Interfaces 1. Detail the process that a router goes through when it receives a frame, and how/why it changes that frame to forward it to its destination. 2. Define the packet forwarding process, or the process of receiving a packet in one interface, and forwarding it out another. Teaching Tip Have students review Simulation 9 (previously viewed in Chapter 5) to reinforce the concepts of encapsulation with a new MAC address at a router. Routing Tables 1. List the information most likely contained in each entry of a routing table, and explain what effect each value has on that entry: a. Destination network b. Next hop c. Metric d. How the route is derived (such as routing protocol, or static routes) e. Timestamp 2. Refer students to Figure 7-9 in their books for a visual example from a Cisco router of what a routing table looks like. Teaching Tip Students should review Simulation 17: Routers Use Multiple Paths in an Internetwork. Routing Protocols 1. Elaborate on what a routing protocol is and what it does. Distinguish this term from routed protocol, which is used to describe IP. A routing protocol helps routers find routes, whereas a routed protocol is one that can be used to reach other computers across multiple discontinuous networks. 2. List the two main types of routing protocol: a. Distance vector, which periodically shares information with neighbors on a network. A common example is Routing Information Protocol (RIP). b. A link-state protocol sends information to other routers about all interface links they are connected to, but only sends this information when a change is detected. 3. Explain the idea of convergence in routing and how it is affected by both of the two protocols previously mentioned. 4. Briefly mention the existence of hybrid protocols if you have time. These protocols combine the best ideas of both link-state and distance vector routing protocols. One of the more widely used hybrid protocols is Cisco’s EIGRP. 5. Lastly, discuss why an administrator might choose static routes over using a routing protocol. You should also detail how static routes do not scale very well and become unruly in large networks. Access Control Lists 1. Explain the use of access control lists (ACLs) to perform packet filtering, much like a firewall. ACLs usually use some combination of the following information to filter packets: a. Source address b. Destination address c. Protocol Teaching Tip Some SOHO routers have the ability to create rudimentary ACLs because they’re marketed as “firewalls”. More sophisticated hardware firewalls can provide better security than a simple router with ACLs. Quick Quiz 2 1. The process of moving a packet from the incoming interface to the outgoing interface is called __________. a. metric checking b. frame forwarding c. packet forwarding d. round-robin Answer: packet forwarding 2. The total number of routers a packet must travel through is called the __________. a. metric b. hop count c. next hop count d. TTL Answer: hop count 3. Which type of routing protocol shares information with other routers by sending the status of all their interface links to other routers in the internetwork? Answer: link-state protocols 4. A(n) __________ is a set of rules configured on a router’s interface for specifying which addresses and which protocols can pass through the interface and to which destinations. Answer: access control list (ACL) 5. In a distance vector routing protocol, where do routers send their routing table information? a. To the next hop b. To their neighbors c. To their default gateway d. To all connected segments Answer: To their neighbors Wireless Access Points in Depth 1. Review with students the basics of a wireless access point. Basic Wireless Settings 1. List what settings a client device will most likely need to connect to a wireless network: a. Wireless network mode b. Wireless network name (SSID) c. Wireless channel d. SSID broadcast status 2. Describe some of the more common wireless modes, such as Mixed, N only, G only, and B only. a. Also explain what selecting some of these modes will do to clients who aren’t compatible. Wireless Security Options 1. Discuss the options available for wireless security, such as a. Encryption b. Authentication c. MAC filtering d. AP isolation 2. When discussing encryption, mention some of the different protocols available, such as WEP and WPA. WEP is just a step above unsecure, but is easily circumvented, while WPA provides more protection. 3. Mention some of the options available for authentication, such as the use of a RADIUS server. 4. Discuss how MAC filtering can be used to secure a wireless network. Students should know that MAC filtering should be combined with other methods, because a potential attacker could simply spoof a MAC address to gain access to the network. 5. Explain that AP isolation works by separating each client connection into a virtual network. Teaching Tip Students may benefit from some information on how basic wireless security settings might be circumvented. In most cases, SOHO network routers are left unsecured or secured with default settings. These devices are very easily broken into. Advanced Wireless Settings 1. Describe some of the more common advanced wireless options available on modern APs: a. Adjustable transmit power b. Multiple SSIDs c. VLAN support d. Traffic priority e. Wi-Fi multimedia f. AP modes Network Interface Cards in Depth 1. Review the responsibilities of a NIC card to connect a computer to a network medium. PC Bus Options 1. Detail some of the common bus options available for installing a NIC card, and briefly list some of their capabilities and limitations: a. PCI b. PCI-X c. PCIe d. PCMCIA e. USB Advanced Features of NICs 1. Discuss what advanced features and options are available for NICs and how these options can affect performance and/or capabilities. Some of the more common options include: a. Shared adapter memory and shared system memory b. Bus mastering c. RAM buffering d. Onboard co-processors e. IPSec f. Quality of service g. Automatic link aggregation h. Fault tolerance i. ACPI compliance j. Preboot Execution Environment (PXE) Quick Quiz 3 1. Name at least two security features most APs offer. Answer: Encryption, Authentication, MAC filtering, AP isolation 2. Which AP feature enables you to restrict which devices can connect to your AP based on their physical address? a. MAC filtering b. Authentication c. Encryption d. AP isolation Answer: MAC filtering 3. Which advanced AP features allows you to assign a priority to packets coming from each network. Answer: traffic priority 4. __________ are credit card–sized expansion cards used mainly to add functionality to laptop computers. Answer: PCMCIA cards Class Discussion Topics 1. Get students to discuss how they might organize switch ports with VLANs given various situations. Give them a scenario, such as a building with multiple floors or a campus network with multiple buildings. How would multiple switches play into their design strategy? Additional Projects 1. Task students with researching some of the more common wireless vulnerabilities. Most importantly, place emphasis on WEP’s vulnerabilities, as these are easily researched. Discuss some of the more recent and groundbreaking attacks against other encryption protocols, such as WPA, using specialized hardware. Additional Resources 1. http://www.isaac.cs.berkeley.edu/isaac/wep-faq.html 2. http://en.wikibooks.org/wiki/CCNA_Certification/Routing_Protocols#Routing_Protocols Key Terms access control list (ACL) A set of rules configured on a router’s interface for specifying which addresses and protocols can pass through the interface and to which destinations. aging time The amount of time a switch maintains a switching table entry that hasn’t been updated. automatic link aggregation A feature that enables you to install multiple NICs in one computer and aggregate the bandwidth so that, for example, you can install two 1 Gbps NICs and have a total bandwidth of 2 Gbps to and from that computer. auto-MDIX A switch port option used to detect the type of device and cable the switch port is connected to; if necessary, the port swaps its transmit and receive pins, which enables you to use a straight-through or crossover cable regardless of the type of device you’re connecting to the port. auto-negotiate mode Communication between a switch and a device connected to a switch port, in which the switch attempts to set the port’s operating mode to the highest performance setting the device supports. blocking mode A mode on a switch port that prevents the switch from forwarding frames out the blocked port, thereby preventing a switching loop. See also switching loop. broadcast storm A condition that occurs when a broadcast frame is forwarded endlessly in a switching loop. See also switching loop. bus mastering A feature that allows a network adapter to take control of the computer’s bus to initiate and manage data transfers to and from the computer’s memory, independent of the CPU. cut-through switching With this switching method, the switch reads only enough of the incoming frame to determine its source and destination addresses. After the forwarding location is determined, the frame is switched internally from the incoming port to the outgoing port, and the switch is free to handle additional frames. destination network The network address of a network to which the router can forward packets. distance-vector protocol A routing protocol that routers use to share information about an internetwork’s status by copying their routing table to other routers with which they share a network. fault tolerance A feature available on some high-end NICs. By installing a second NIC in a PC, failure of the primary NIC shifts network traffic to the second NIC instead of cutting off the PC from the network. flood The process whereby a switch forwards a frame out all connected ports. fragment-free switching With this switching method, the switch reads enough of the frame to guarantee that it’s at least the minimum size for the network type, reducing the possibility that the switch will forward a frame fragment. frame fragment An invalid frame that’s damaged because of a collision or a malfunctioning device. hop Each router a packet must go through to get to the destination network. hop count The total number of routers a packet must travel through to get to its destination network. link-state protocol A routing protocol that a router uses to share information with other routers by sending the status of all its interface links to all other routers in the internetwork. The status includes link speed, whether the link is up or down, and the link’s network number. managed switch A high-end switch with many advanced features that can be configured. metric A numeric value that tells the router how “far away” the destination network is. It can be composed of values such as the bandwidth of links between the source and destination, the hop count, and the link’s reliability. neighbor In an internetwork, routers sharing a common network. next hop An interface name or the address of the next router in the path to the destination network. onboard co-processors A feature included on most NICs that enables the card to process incoming and outgoing network data without requiring service from the CPU. packet filtering A process whereby a router blocks a packet from being forwarded based on rules specified by an access control list. See also access control list (ACL). packet forwarding The process of a router receiving a packet on one port and forwarding it out another port based on the packet’s destination network address and information in the routing table. PCI Express (PCIe) A bus standard that uses a high-speed serial communication protocol of one or more lines or lanes. Each lane of PCIe 1.0 can operate at 250 Mbps in each direction. See also Peripheral Component Interconnect (PCI). PCI-X A bus standard that’s backward-compatible with PCI and supports speeds of 66 to 533 MHz with 32-bit or 64-bit bus widths. See also Peripheral Component Interconnect (PCI). PCMCIA cards Credit card–sized expansion cards used mainly to add functionality to laptop computers. The main standards are Cardbus and Express Card. Cardbus operates at 33 MHz and supports a 32-bit bus; Express Card uses PCIe technology to provide data transfer speeds up to 500 Mbps. Peripheral Component Interconnect (PCI) A bus standard used to connect I/O devices to the memory and CPU of a PC motherboard. PCI is implemented in both 32-bit and 64-bit versions at speeds of 33 and 66 MHz, respectively. Quality of Service (QoS) A feature that allows a NIC to prioritize time-sensitive data, such as streaming video and voice. RAM buffering A NIC feature for including additional memory to provide temporary storage for incoming and outgoing data. Routing Information Protocol (RIP) A distance-vector protocols that use hop count as the metric to determine the best path to a destination network. Routing Information Protocol version 2 (RIPv2) A newer version of RIP that supports a more complex IP address scheme and uses multicast packets rather than broadcast packets to transmit routing table updates. routing protocol A set of rules routers use to exchange information so that all routers have accurate information about an internetwork to populate their routing tables. shared adapter memory A feature on some NICs in which the NIC’s buffers map directly to RAM on the computer. A computer actually writes to buffers on the NIC instead of writing to its own memory. shared system memory A feature on some NICs in which a NIC’s onboard processor selects a region of RAM on the computer and writes to it as though it were buffer space on the adapter. smart switch A midrange switch with some advanced features, typically multicast processing, Spanning Tree Protocol, VLANs, and port security. See also Spanning Tree Protocol (STP) and virtual local area networks (VLANs). Spanning Tree Protocol (STP) A communication protocol switches use to ensure that they aren’t connected in a way that creates a switching loop. See also switching loop. static route A routing table entry that’s entered manually by an administrator. store-and-forward switching This switching method requires the switch to read the entire frame into its buffers before forwarding it. It examines the frame check sequence (FCS) field to be sure the frame contains no errors before it’s forwarded. switching loop A condition that occurs when switches are connected in such a way that frames can be forwarded endlessly from switch to switch in an infinite loop. trunk port A switch port configured to carry traffic from all VLANs to another switch or router. See also virtual local area networks (VLANs). Universal Serial Bus (USB) An external PC bus interface for connecting I/O devices. Speeds range from 12 Mbps in USB 1.0 to 3.2 Gbps in USB 3.0. virtual local area networks (VLANs) A feature on some switches that allows configuring one or more switch ports into separate broadcast domains. Technical Notes for Hands-On Projects All projects in this book that use the Sharing and Security option for folders assume that the Use simple file sharing option has been disabled. Hands-On Project 7-1: This project requires two computers (one with Wireshark installed), two switches that don’t have STP enabled, two patch cables, and two crossover cables (or four patch cables if your switches support auto-MDIX). Hands-On Project 7-2: This project requires a classroom computer. Using Virtualization for Hands-On Projects The following Hands-On Projects/Challenge Labs have been identified as those that students can do using virtual machines rather than physical machines. Hands-on Project 7-2 Instructor Manual for Guide to Networking Essentials Gregory Tomsho 9781111312527, 9781305105430, 9788131502136
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