CHAPTER 12 : Network Troubleshooting Methodology 636 You are the administrator of the network shown in Figure 12.15. 13. The user of Computer1 is unable to access a shared resource located on Computer3. Computer1 is able to access shared resources on other subnets on the internal network as well as the Internet. Computer3 is able to access shared resources on Computer5 and Computer7, as well as resources on the Internet. When you ping Computer1 from Computer3, you receive a “Request Timed Out” message. Based on this information, what is the most likely cause of the connectivity issue? A. The router interface attached to Subnet D is malfunctioning. B. The router interface attached to Subnet C is malfunctioning. C. Router B does not have a route from Subnet C to the Internet. D. Router B does not have a route from Subnet C to Subnet D. FIGURE 12.15 Sample network architecture. Self Test Quick Answer Key 637 A user connected to Subnet B is able to use the resources housed on 14. a machine named Server A which is located on Subnet W without trouble. When the same user is working from a d ifferent location, their machine obtains an IP address from DHCP on Subnet D and they are no longer able to connect to Server A. You have been attempting to determine the problem. So far you have utilized the ipconfig tool to verify the IP configuration of both the server and the client, and both appear correct. Which of the following trouble- shooting steps would be a logical next choice? Choose all that apply. A. From the user workstation on Subnet D, ping the default gateway. B. From Server A, ping the default gateway. C. From the user workstation, ping another machine on the same subnet as Server A. D. From the user workstation, ping the loopback address. Your e-mail server is having network connectivity problems. You 15. have replaced the NIC and reconfigured the IP address. The last step that you take is to start the e-mail services and all services have now started successfully without generating error messages. Which of the following actions will allow you to verify that the e-mail services are successfully accepting inbound e-mail? A. Telnet from a client machine to port 25 on the e-mail server. B. Telnet from a client machine to port 23 on the e-mail server. C. Use POP3 to create an e-mail queue and validate that e-mail passes through it successfully. D. Use IMAP4 to send Internet e-mail to the server. SELF TEST QUICK ANSWER KEY B1. C2. A, D, E, and F3. B4. B5. A and C6. D7. A8. A and B9. A10. A and C11. B12. D13. A and C14. A 15. This page intentionally left blank 639 THE INSTITUTE OF ELECTRICAL AND ELECTRONICS ENGINEERS (IEEE) IEEE Committee IEEE is an acronym for the “Institute of Electrical and Electronics Engineers,” which is an organization that develops and promotes standards dealing with various technologies. These standards serve as the principles and guidelines for technology. While they aren’t government regulations that need to be followed, they are industry standards that should be followed. While IEEE standards have been used when regulations need to be created, the importance of the IEEE is really seen outside government regulatory standards. Those who design and manufacture equipment and software look to these standards so their products can be compliant with IEEE standards. For example, if you bought a digital camera, you would want to be able to transfer the pictures to your computer. Without standards, cameras might use different cables or ports to transfer this data, meaning that you couldn’t transfer the data easily to any computer. Apple developed FireWire as a method of connecting devices to computers and transferring large amounts of data quickly, and IEEE 1394 was developed as a nonproprietary standard of transferring audio and video. Without such standards, your devices would work with one type of computer (such as a laptop), but not with others (such as a desktop). By adhering to these standards, products have the ability to be compatible with other technologies and can operate with other equipment. History and Fundamentals of IEEE The IEEE was formed in 1963 from a merger of two other organizations: the American Institute of Electrical Engineers (AIEE) and the Institute of Radio Engineers (IRE). The AIEE was founded in 1884, as one of a number of engineer- ing societies at that time. It succeeded in developing industry and professional standards for those involved in the electrical and engineering fields. As new technologies emerged, it formed committees to address specialized fields. The Institute of Radio Engineers was founded in 1912, as an amalgamation of two earlier societies, and focused on obtaining international memberships. Appendix A Appendix A 640 This organization focused on issues of standardization in radio, not only affecting manufacturing, but also assisted in developing broadcasting regulations and were part of conferences that led to the formation of the Federal Radio Commission in 1927, which later became the Federal Com- munications Commission (FCC). As technologies advanced, the IRE also assisted in standards dealing with FM radio and television. While the IRE started as the smaller organization of the two, it eventually gained a greater membership than the AIEE. However, neither organization fully represented all fields associated with electrical or electronic engineering. This lead to a merger between the IRE and the AIEE in 1963, and inspired the name change to the Institute of Electrical and Electronic Engineers. Over the years, the IEEE has developed and promoted numerous standards, provided education through publications and journals, and expanded its role in electricity, electronics, and communications to also include computers. By creating committees to address emerging technologies and developments in computer engineering and computer science, it has been predominant in providing the standards used in computer hardware, software, and networking. 802 Standards IEEE standards use a numeric naming scheme to identify and group the technologies being addressed. Those standards beginning with the number 802 relate to networking, and are developed and evaluated by specialized committees within IEEE. The 802 committee was first formed as a proj- ect in February 1980, and became known as Project 802 after the year (80) and month (2) it was created. After more than two decades, it continues to review and provide industry standards for local area networks. The 802 committee is broken down into smaller subcommittees or working groups that focus on specific aspects of networking. The various groups that have worked on standards include: 802.1 Higher Layer LAN Protocols 802.2 Logical Link Control (LLC) (inactive) 802.3 Carrier Sense Multiple Access with Collision Detection (CSMA/CD) – Ethernet 802.4 Token Bus (disbanded) 802.5 Token Ring (inactive) 802.6 Metropolitan Area Network (disbanded) Appendix A 641 802.7 Broadband (disbanded) 802.8 Fiber Optic (disbanded) 802.9 Isochronous LAN (disbanded) 802.10 Security (disbanded) 802.11 Wireless LAN (WLAN) 802.12 Demand Priority (inactive) 802.14 Cable Modem 802.15 Wireless Personal Area Network (WPAN) 802.16 Broadband Wireless Access 802.17 Resilient Packet Ring 802.18 Radio Regulatory 802.19 Coexistence 802.20 Mobile Broadband Wireless Access (MBWA) 802.21 Media Independent Handoff 802.22 Wireless Regional Area Networks Because technology changes, so do the working groups. New working groups are added to address emerging technologies, while others are disbanded or become inactive. Reasons for disbanding or making a group inactive varies, but when older technology isn’t used as much or further standards aren’t required, it makes sense to evaluate the need for a group. An up-to-date list of working groups and their status can be found on the IEEE Web site at http://grouper.ieee.org/groups/802/dots.html. OSI and 802 The services and protocols specified in the 802 standards correspond to the lower layers of the OSI model. OSI is an acronym for “Open Systems Interconnect”, and the OSI model is a seven-layer structure that maps to a logical structure for network operations. It is often used to show how protocols work, and what happens when data is sent over a LAN. When communication is sent over a network, it starts at the topmost layer, and works its way down to the bottom layers. The bottommost layers of the OSI model are the Data Link and Physical Layers. Earlier, we mentioned how data is broken into smaller pieces before Appendix A 642 it is sent over a network, which is a primary function of the Data Link Layer. When another computer receives these pieces of data, they are reassembled at the Data Link Layer and passed up to higher layers so they can be further assembled into the data’s original format and be used by an application. The 802 standards break the Data Link Layer of the OSI model into two separate subcategories: LLC and Media Access Control (MAC). The LLC is responsible for starting and maintaining connections with devices, while the MAC allows multiple devices to share the media (that is coaxial cable, twisted-pair, and so on) that data is being sent over. In other words, when you send data to another computer, it is the LLC that establishes the connection with the other computer, and it is the MAC that allows more than one computer to communicate on the network. The Physical Layer of the OSI model deals with how data moves on and off the network media. While it doesn’t specify what media is used, it does identify how it is accessed. This includes the topology of the network, electrical and physical aspects of media, and the timing and encoding used for transmitting and receiving bits of data. Table of Standards IEEE working groups have generated a large number of standards over the years. As you can see by these standards, each uses the numeric value of 802 to show it is part of the 802 committee’s networking standards. A decimal value is used to designate the working group that developed it, and to show the standard it relates to, while a letter further categorizes specifications, supplements and other addendum. While the 802 standards can be seen in the following table, a full listing of IEEE standards can be found on the organization’s Web site at http://info.computer.org/standards/standesc.htm. Table A.1 Listing of 802 IEEE Standards Standard Subject\Description 802 Standard for Local Area Networks for Computer Interconnection. Provides compatibility between devices that have been made by different manufacturers 802.1 Architecture and Overviews. Standard for allowing LAN or MAN to communicate with another LAN or MAN 802.1b LAN/MAN Management. Defines network management architecture and protocols at OSI layers 1 and 2 802.1d MAC Sublayer Interconnection: MAC Bridges. Standard defining internetworking two or more LANs at the MAC sublayer 802.1e System Load Protocol. Standard on loading a LAN station’s local address space Appendix A 643 Table A.1 Listing of 802 IEEE Standards continued Standard Subject\Description 802.1f Recommended Practices for the Development of Layer Management Stan- dards. Standard on common management activities across the OSI layers 802.1g MAC Sublayer Interconnection. Standard on internetworking two or more LANs at the MAC sublayer 802.1h LAN: Token Ring Access Method and Physical Layer Specifications 802.1I Standard MAC Bridges: Fiber Distributed Data Interface (FDDI) Supplement 802.1j Managed Objects for MAC Bridges. Standard that manages objects for MAC bridges (corresponds to 802.1d) 802.1k LAN/MAN Management Information for Monitoring and Event Reporting 802.1m System Load Protocol: Managed Object Definition and Protocol Implementa- tion Conformance Statement (PICS) Proforma. Specifies the System Load Protocol parameters for conformance 802.2 Local Area Networks: LLC. Standard on the link layer protocol, which provides confirmation on the delivery of data over a LAN 802.2a Flow Control Techniques for Bridges – Local Area Networks 802.2b Acknowledged Connectionless-mode Service Type 3 Operation 802.2c Standard for LLC Conformance Requirements 802.2d Supplement to 802.2, Information Processing Systems: LAN Part2: LLC. Provides changes and corrections to the 802.2 standard 802.2e Supplement to 802.2, Information Processing Systems: LAN Part2: Bit Referencing 802.2f Standard for LLC Sublayer Management. Standard on sublayer management of the LLC 802.2g Supplement to 802.2, LLC Type 4 (High Speed, High Performance) Operation 802.3 Local Network for Computer Interconnection (CSMA/CD). Standard for CSMA/CD or Ethernet. This provides a standard for communication devices to be compatible, so there is little to no need for customizing hardware and software 802.3a Medium Attachment Unit (MAU) and Baseband Medium Specifications for Type 10Base2. Supplement for 10 Mbps baseband media 802.3b Section 11, Broadband MAU and Broadband Medium Specifications. Supplement to add broadband capabilities to 10 Mbps media 802.3c Local Area Networks: Repeater Unit. Defines a standard baseband repeater for 10BaseX networks, which allows the interconnection of multiple coaxial segments 802.3d MAU and Baseband Medium Specification for Fiber Optic Inter-Repeater Unit. Specifications for fiber optic interconnections for 10Base5 and 10Base2 networks Continued Appendix A 644 Table A.1 Listing of 802 IEEE Standards continued Standard Subject\Description 802.3e Physical Signaling, Medium Attachment and Baseband Medium Specification, Type 1Base5. Implements a 1 Mbps baseband physical layer for CSMA/CD, using twisted-pair media on a star topology network 802.3h Layer Management. Supplement replaces a paragraph in the existing standard 802.3I MAU and Baseband Medium Specs, Type 10BaseT. Specifications for a MAU and media on a LAN using CSMA/CD, so that it can operate at 10 Mbps on twisted-pair media 802.3j Fiber Optic Active and Passive Star Based 802.3 Segment. Supplement for 802.3 802.3k Standard for Repeater Management (revision) 802.3l Supplement to CSMA/CD Access Method and Physical Layer Specifications: MAU, Type 10BaseT PICS Proforma 802.3m Supplement to CSMA with Collision Detection CSMA/CD Access Method and Physical Layer Specifications (Second Maintenance Ballot) 802.3n Supplement to CSMA/CD Access with Collision Detection CSMA/CD Access Method and Physical Layer Specifications (Third Maintenance Ballot) 802.3p CSMA/CD Layer Management for 10 MB/S 802.3q CSMA/CD GDMO Format for Layer Managed Objects 802.3r Supplement to CSMA with CSMA/CD Access Method and Physical Layer Specifications: Type 10BASE5 MAU PICS 802.3s CSMA/CD Access Method and Physical Layer Specifications: Maintenance Revision #4. Revisions that provide corrections and updates 802.3t Supplement to CSMA/CD Access Method and Physical Layer Specifications: Informative Annex for Support of 120 Ohm Cables in 10Base-T Simplex Link Segment 802.3u Supplement to CSMA/CD Access Method and Physical Layer Specifications: MAC Parameters, Physical Layer, MAUs and Repeater for 100 Mb/s Operation 802.3v Supplement to CSMA/CD Access Method and Physical Layer Specifications: Informative Annex for Support of 150 Ohm Cables in 10BASE-T Link Segment 802.4 Revision LAN: Token-Bus Access Method 802.4a Fiber Optic Token Bus. Specifications for using fiber optic media and adding an additional physical layer to 802.4 802.4b Redundant Media Control Unit. Addendum that deals with connecting multiple media to a single MAC, and improving physical layer reliability 802.5 LAN: Token Ring Access Method and Physical Layer Specifications 802.5a LAN: Station Management Revision 802.5b LAN: Telephone Twisted Pair Media. Specification for using twisted-pair media in a token ring network Appendix A 645 Table A.1 Listing of 802 IEEE Standards continued Standard Subject\Description 802.5c LAN: Token Ring Reconfiguration. Specification that adds automatic fault recovery 802.5d LAN: Interconnected Token Ring LANs. Specification on multi-ring operations 802.5e LAN: Token Ring Station Management Entity Specifications 802.5f LAN: 16 Mbps Token Ring Operations. Specifications for change 4 Mbps Rings to 16 Mbps 802.5g LAN: Conformance Testing 802.5h LAN: Operation of LLC III on Token Rings 802.5I LAN: Token Ring; Early Token Release 802.5j LAN: Fiber Optic Station Attachment 802.5k Token Ring Media Specification 802.5l Maintenance of Token Ring Standard. Revision of token ring access method and physical layer specifications 802.5m Recommended. Practice to Interconnection of Source Routed and Transparent Bridged Networks 802.5n Unshielded Twisted Pair at 4/16 Mbps. Standard for operating 4 Mbps and 16 Mbps Token Ring LANs on unshielded twisted-pair 802.5p LAN: Part 2: LLC; End System Determination 802.5q LAN: Part 5: MAC Revision 802.5r Revision of IEEE Standard 802.5 for Token Ring Station Attachment 802.6 Standard for the Distributed Queue Dual Bus Metropolitan Area Networks. Standard used for Metropolitan Area Networks (MAN), which is used in specifying the MAC sublayer and physical layer 802.6a Multiple Port Bridging for MAN. Standard for services provided by multiple bridge ports, which are used to connect two or more Dual Bus subnetworks together 802.6b Standard for Premises Extension of DS3-Based 802.6 MAN 802.6c Standard for DS1 Physical Layer Convergence Procedures 802.6d Standard for SONET (SDH) Based Physical Layer Convergence Procedures for 802.6 MAN 802.6e Standard for Eraser Node for DQDB MAN 802.6f PICS Proforma 802.6g Standard for Layer Management for the 802.6 MAN 802.6h Standard for Isochronous Services Over the 802.6 MAN 802.6I Standard for Remote LAN Bridging Using the 802.6 MAN. Specifies protocols used between remote LAN bridges Continued . Information Processing Systems: LAN Part2 : LLC. Provides changes and corrections to the 802.2 standard 802.2e Supplement to 802.2, Information Processing Systems: LAN Part2 : Bit Referencing 802.2f. Mbps and 16 Mbps Token Ring LANs on unshielded twisted-pair 802.5p LAN: Part 2: LLC; End System Determination 802.5q LAN: Part 5: MAC Revision 802.5r Revision of IEEE Standard 802.5 for Token Ring. the years. As you can see by these standards, each uses the numeric value of 802 to show it is part of the 802 committee’s networking standards. A decimal value is used to designate the working