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The most complete guide to Cisco Catalyst(r) switch network design, operation, and configuration
Cisco LAN Switchingprovides the most comprehensive coverage of the best methods for designing, utilizing, and deploying LAN switching devices and technologies in a modern campus network. Divided into six parts, this book takes you beyond basic switching concepts by providing an array of proven design models, practical implementation solutions, and troubleshooting strategies. Part I discusses important foundation issues that provide a context for the rest of the book, including Fast and Gigabit Ethernet, routing versus switching, the types of Layer 2 switching, the Catalyst command-line environment, and VLANs. Part II presents the most detailed discussion of Spanning-Tree Protocol in print, including common problems, troubleshooting, and enhancements, such as PortFast, UplinkFast, BackboneFast, and PVST+. Part III examines the critical issue of trunk connections, the links used to carry multiple VLANs through campus networks. Entire chapters are dedicated to LANE and MPOA. Part IV addresses advanced features, such as Layer 3 switching, VTP, and CGMP and IGMP. Part V covers real-world campus design and implementation issues, allowing you to benefit from the collective advice of many LAN switching experts. Part VI discusses issues specific to the Catalyst 6000/6500 family of switches, including the powerful Native IOS Mode of Layer 3 switching.
Several features in Cisco LAN Switchingare designed to reinforce concepts covered in the book and to help you prepare for the CCIE exam. In addition to the practical discussion of advanced switching issues, this book also contains case studies that highlight real-world design, implementation, and management issues, as well as chapter-ending review questions and exercises.
This book is part of the Cisco CCIE Professional Development Series from Cisco Press, which offers expert-level instruction on network design, deployment, and support methodologies to help networking professionals manage complex networks and prepare for CCIE exams.
The legacy networks continue to find utility as distribution and backbone technologies for both manufacturing and office environments. But like ArcNet and StarLAN, even these technologies see higher speed networks such as Fast Ethernet, High Speed Token Ring, and ATM crowding into the network arena. However, the legacy systems will remain for many more years due to the existence of such a large installed base. Users will replace Ethernet and Token Ring in phases as applications demand more bandwidth.
This chapter discusses the legacy network technologies, Ethernet and Token Ring, as well as Fast Ethernet and Gigabit Ethernet. Although Gigabit Ethernet is not yet a popular desktop technology, it is discussed here because of its relationship to Ethernet and its use in Catalyst networks for trunking Catalysts together. This chapter also describes how the access methods operate, some of the physical characteristics of each, and various frame formats and address types.
When mainframe computers dominated the industry, user terminals attached either directly to ports on the computer or to a controller that gave the appearance of a direct connection. Each wire connection was dedicated to an individual terminal. Users entered data, and the terminal immediately transmitted signals to the host. Performance was driven by the horsepower in the hosts. If the host became overworked, users experienced delays in responses. Note, though, that the connection between the host and terminal was not the cause in the delay. The users had full media bandwidth on the link regardless of the workload of the host device.
Facility managers installing the connections between the terminal and the host experienced distanc e constraints imposed by the host's terminal line technology. The technology limited users to locations that were a relatively short radius from the host. Further, labor to install the cables created inflated installation and maintenance expenses. Local-area networks (LANs) mitigated these issues to a large degree. One of the immediate benefits of a LAN was to reduce the installation and maintenance costs by eliminating the need to install dedicated wires to each user. Instead, a single cable pulled from user to user allowed users to share a common infrastructure instead of having dedicated infrastructures for each station.
A technology problem arises when users share a cable, though. Specifically, how does the network control who uses the cable and when? Broadband technologies like cable television (CATV) support multiple users by multiplexing data on different channels (frequencies). For example, think of each video signal on a CATV system as a data stream. Each data stream is transported over its own channel. A CATV system carries multiple channels on a single cable and can, therefore, carry multiple data streams concurrently. This is an example of frequency-division multiplexing (FDM). The initial LANs were conceived as baseband technologies, however, which do not have multiple channels. Baseband technologies do not transmit using FDM. Rather, they use bandwidth-sharing, which simply means that users take turns transmitting.
Ethernet and Token Ring define sets of rules known as access methods for sharing the cable. The access methods approach media sharing differently, but have essentially the same end goal in mind.
Carrier Sense with Multiple Access with Collision Detection (CSMA/CD)
Carrier sense multiple access collision detect (CSMA/CD) describes the Ethernet access method. CSMA/CD follows rules similar to those in a meeting. In a meeting, all individuals have the right to speak. The unspoken rule that all follows, though, is "Only one person can talk at a time." If you have something to say, you need to listen to see if someone is speaking. If someone is already speaking, you must wait until they are finished. When you start to speak, you need to continue to listen in case someone else decides to speak at the same time. If this happens, both parties must stop talking and wait a random amount of time. Only then do they have the right to start the process again. If individuals fail to observe the protocol of only one speaker at a time, the meeting quickly degenerates and no effective communication occurs. (Unfortunately, this happens all too often.)
In Ethernet, multiple access is the terminology for many stations attaching to the same cable and having the opportunity to transmit. No station has any priority over any other station. However, they do need to take turns per the access algorithm.
Carrier sense refers to the process of listening before speaking. The Ethernet device wishing to communicate looks for energy on the media (an electrical carrier). If a carrier exists, the cable is in use and the device must wait to transmit. Many Ethernet devices maintain a counter of how often they need to wait before they can transmit. Some devices call the counter a deferral or back-off counter. If the deferral counter exceeds a threshold value of 15 retries, the device attempting to transmit assumes that it will never get access to the cable to transmit the packet. In this situation, the source device discards the frame. This might happen if there are too many devices on the network, implying that there is not enough bandwidth available. When this situation becomes chronic, you should segment the network into smaller segments. Chapter 2, "Segmenting LANs, " discusses various approaches to segmentation. If the power level exceeds a certain threshold, that implies to the system that a collision occurred. When stations detect that a collision occurs, the participants generate a collision enforcement signal. The enforcement signal lasts as long as the smallest frame size. In the case of Ethernet, that equates to 64 bytes. This ensures that all stations know about the collision and that no other station attempts to transmit during the collision event. If a station experiences too many consecutive collisions, the station stops transmitting the frame. Some workstations display an error message stating Media not available. The exact message differs from implementation to implementation, but every workstation attempts to convey to the user that it was unable to send data for one reason or another.
Addressing in Ethernet
How do stations identify each other? In a meeting, you identify the intended recipient by name. You can choose to address the entire group, a set of individuals, or a specific person. Speaking to the group equates to a broadcast; a set of individuals is a multicast; and addressing one person by name is a unicast. Most traffic in a network is unicast in nature, characterized as traffic from a specific station to another specific device. Some applications generate multicast traffic. Examples include multimedia services over LANs. These applications intend for more than one station to receive the traffic, but not necessarily all for all stations. Video conferencing applications frequently implement multicast addressing to specify a group of recipients. Networking protocols create broadcast traffic, whereas IP creates broadcast packets for ARP and other processes. Routers often transmit routing updates as broadcast frames, and AppleTalk, DecNet, Novell IPX, and many other protocols create broadcasts for various reasons.
Figure 1-1 shows a simple legacy Ethernet system with several devices attached. Each device's Ethernet adapter card has a 48-bit (6 octet) address built in to the module that uniquely identifies the station. This is called the Media Access Control (MAC) address, or the hardware address. All of the devices in a LAN must have a unique MAC address. Devices express MAC addresses as hexadecimal values. Sometimes MAC address octets are separated by hyphens (-) sometimes by colons (:) and sometimes periods (.). The three formats of 00-60-97-8F-4F-86,00:60:97:8F:4F:86, and 0060.978F.4F86 all specify the same host. This book usually uses the first format because most of the Catalyst displays use this convention; however, there are a couple of exceptions where you might see the second or third format. Do not let this confuse you. They all represent MAC addresses.....
Despite the popularity of campus switching equipment, it has been very difficult to obtain detailed and clear information on how it should be designed, utilized, and deployed. Although many books have been published in the last several years on routing technology, virtually no books have been published on LAN switching. The few that have been published are vague, out-of-date, and absent of real-world advice. Important topics such as the Spanning-Tree Protocol and Layer 3 switching have either been ignored or received inadequate coverage. Furthermore, most have contained virtually no useful information on the subject of campus design.
This book was written to change that. It has the most in-depth coverage of LAN switching technology in print to date. Not only does it have expansive coverage of foundational issues, but it is also full of practical suggestions. Proven design models, technologies, and strategies are thoroughly discussed and analyzed.
Both authors have drawn on their extensive experience with campus switching technology. As two of the first certified Catalyst instructors,they have first-hand knowledge of how to effectively communicate switching concepts.
Through design and implementation experience, they have a detailed understanding of what works, as well as what doesn't work.
Cisco LAN Switching is designed to help people move forward with their knowledge of the exciting field of campus switching. ME candidates will receive broad and comprehensive instruction on a wide variety of switchingrelated technologies. Other network professionals will also benefit from hard-to-find information on subjects such Layer 3 switching and campus design best practices.
Cisco LAN Switching should appeal to a wide variety of people working in the network field. It is designed for any network administrator, engineer, designer, or manager who requires a detailed knowledge of LAN switching technology.
Obviously, the book is designed to be an authoritative source for network engineers preparing for the switching portion of the CCIE exams and Cisco Career Certifications. Cisco LAN Switching is not a "quick fix" guide that helps you cram (such books are virtually worthless when it comes to taking the ME practical exams). Instead, it focuses extensively on theory and building practical knowledge. When allied with hands-on experience, this can be a potent combination.
However, this book is designed to go far beyond test preparation. It is designed to be both a tutorial and a reference tool for a wide range of network professionals, including the following:
The eighteen chapters of this book fall into five parts:
Features and Conventions
Where applicable, each chapter includes a variety of questions and exercises to further your knowledge of the material covered in that chapter. Many of the questions probe at the theoretical issues that indicate your mastery of the subject matter. Other questions and exercises provide an opportunity to build switching scenarios yourself. By utilizing extra equipment you might have available, you can build your own laboratory to explore campus switching. For those not fortunate enough to have racks of idle switching gear, the authors will be working with MentorLabs (http://www.mentorlabs.com) to provide value-added labs via the Internet. Two conventions are used to draw your attention to sidebar, important, or useful information:
TIP: Tips are used to highlight important points or useful shortcuts.
NOTE: Notes are used for sidebar information related to the main text.
Various elements of Catalyst and Cisco router command syntax are presented in the course of each chapter. This book uses the same conventions as the Cisco documentation:
Posted January 4, 2005
Cisco LAN Switching by Kennedy Clark and Kevin Hamilton is considered a definitive guide to Cisco switching ¿ and rightly so. The book contains an exhaustive presentation on all aspects of switching ¿ from the basics of switching technologies, to the protocols and algorithms used in campus switching, to real-world designs of campus switching environments. All this with an added bonus of tidbits of humor thrown into the discussion of serious, no-nonsense topics! The book is surprisingly well written and easy to understand for readers who have a basic understanding of switching and routing in the Cisco world. The formatting in the book follows the standard Cisco layout for advanced level books. The headings, diagrams, tables, and notes are laid out in a clear and easy-to-scan format. Each chapter ends with review questions for those who wish to test their understanding of the material ¿ these can prove particularly useful for the readers who may be studying for one of the Cisco certifications. The index is a crucial part of any technical book. Those of us working in the field can appreciate the importance of having a detailed and useful index when trying to put out fires at the workplace. This book offers a comprehensive, detailed index ¿ spanning over 30 pages -- which provided me with useful knowledge on the topic(s) that I was trying to look up. While the book claims to be a switching resource for those studying for the advanced Cisco certifications, I personally selected the book in order to help me in my work environment. It has served its purpose very well. The sample configurations given throughout the book for various situations were particularly helpful in tying the theory to the practical and especially helped in troubleshooting some of the issues I encounter every day. Presentation of the inner workings of some of the advanced material like the Spanning Tree protocol was surprisingly detailed and practical, while being easy to understand at the same time. I have not read any other book that covers this topic effectively with such detail. The only suggestion I have for the authors is to look into writing an updated edition. Some of the topics ¿ like layer 3 switching ¿ do not seem to cover the latest switch types offered by Cisco. For example, the Cisco 3550 layer 3 switch, a popular and important milestone in the Cisco switching hierarchy, is not covered in any significant detail. Overall, the authors present the material in a very well thought-out way, making sure that readers at all (reasonable) levels can understand the topics. At the same time, the material is not fluffy like some other books; it is a detailed, no-nonsense study of the important field of campus switching.Was this review helpful? Yes NoThank you for your feedback. Report this reviewThank you, this review has been flagged.
Posted January 29, 2004
While I was preparing for the CCNP, I was hard pressed to find just the right book that explained LAN switching in depth. Now that I am preparing for my CCIE, this is the book I was looking for. This is one of the most comprehensive texts on Cisco LAN switching I¿ve seen. It breaks down switching concepts into easy to understand topics. You don¿t have to be an expert at switching to understand the topics addressed in this book. It begins with basic switching technologies and progresses into more advanced topics. Cisco LAN Switching is broken down into 6 sections. Section 1 is concerned with foundational issues and gives an excellent introduction to bridging and switching technologies. The other sections progress through VLANS and STP to Trunking and advanced topics. Each chapter concludes with review questions and the later chapters have hands on lab configurations. The book ends with real world campus design models, implementation and case studies, which tie all the earlier sections together. Each topic is thoroughly explained and the diagrams and definitions help clarify certain areas. I also found the tips and notes in the chapters very helpful in understanding the material better. Another interesting point is that the chapters dealing with STP were reviewed by Radia Perlman, creator of the Spanning Tree algorithm. Even without a whole lot of exposure to the spanning tree protocol, the material was presented in an easy to understand format. However there were a few issues I did have with the some of the content and the layout of the sections dealing with trunking. The first chapter addresses the basics of LAN switching and bridging but does not go into enough depth on the different bridging technologies. I believe an expanded discussion on bridging technologies (SRB, RSRB and DLSW+) would have been helpful as well as a section on deciphering an RIF. The section on trunking technologies goes into great depth about different types of trunking, including a wide array of diagrams and tables explaining each technology. While the subject matter is thoroughly covered, I do have an issue concerning the layout of the chapters. The authors devote an entire section of the book to trunking technologies, yet they place the chapter on VTP in an entirely different section of the book. I believe the flow of the chapters would have been more consistent if VTP was addressed in the section on trunking technologies. These small issues aside, I found this book very helpful for my studies toward the CCIE and also in implementing better switching technologies in my company¿s network. I would definitely recommend this book to anyone who plans on using any type of switching in their network environment or those studying for Cisco certification. However, this book should not be used solely as a study resource and then be put aside; it should be an integral part of any network administrator¿s reference library.Was this review helpful? Yes NoThank you for your feedback. Report this reviewThank you, this review has been flagged.
Posted November 30, 2003
While studying for my R&S lab attempt I felt that one of my weak understandings was the fundamental design and implementation of intricate network switching. I had gone through other books in preparation for the CCNP switching exam, and many of the other CCIE preparation books (i.e. Caslow, Doyle, Bruno.) I understood how to implement the typical configurations as per many of the practice lab workbook materials, but I was unable to grasp the immense capabilities of the current Catalyst line of equipment. The book begins with a lesson of Ethernet development. It brought an understanding the road to current network deployment with an eye on the future of the technology. Explanations of the politics and business needs that brought the 802.3 group standards into use helped in teaching the capabilities of them. While troubleshooting many large enterprise networks I have been witness to extremely poor network segmentation (¿when in doubt, bridge everything!¿) I would really recommend that all administrators use this book to more fully apprehend the benefits of avoiding a flat network and segmenting to realize the network utilization potential. Fast network convergence and understanding spanning-tree is necessary in any moving network design. The lessons on VLAN trunking protocol, configuration, and design touched was written to easily help with real world completion. With the recent troubles of Welchia, Blaster, and Nachi, implementing a flexible network that can be responsive and designed to protect users should be one of the top responsibilities for any responsible admin. In chapter 14, the explanation of equipment and design to executing an access, distribution, and core network design provided a very handy top down view of proper redesign project development. It provided advantages, disadvantages, and great practical advice for an exhaustive list of campus design models. One of the most beneficial aspects of the design chapters was an excellent use of network design exercises of which I have made several uses in my lab environment. It is my personal belief that developing excellent philosophical troubleshooting fundamentals is one of the most important skills necessary to completing the R&S lab within time limits, and also in keeping any clients network alive and well in any business environment. Chapter 16 provided more than the usual end of chapter lesson on troubleshooting your switched environment. The books final chapter on Catalyst 6000/6500 technology has been my best guide to understanding the platform. Though not tested in the R&S lab environment the 6000/6500 platform has been extremely important to understand in my direct line of work. After reading the section my confidence in using the line has greatly improved. Cisco Lan Switching is the definitive guide to understanding segmentation, trunking, and advanced spanning-tree. The STP chapters are possibly the best written material on the subject that is available. While the book doesn¿t provide information on the 3550 (published 2001) it does overview L3 switching quite nicely. And although no longer a CCIE R&S lab requirement, the chapter on ATM LANE helped clear many of my previous fears on the subject. The book was an excellent read, the chapters and materials flowed well with brief overviews at the beginning of each chapter. This book is a pillar to any CCIE library!Was this review helpful? Yes NoThank you for your feedback. Report this reviewThank you, this review has been flagged.
Posted May 30, 2000
I am extremely happy with this book. I covers all necessary details on LAN design and operation using Catalyst switches. Even talks about MSFC for Cat6500. I did wish for more detail on the Cat6500 in 'Native' IOS mode, but overall a must for LAN admins/engineers.Was this review helpful? Yes NoThank you for your feedback. Report this reviewThank you, this review has been flagged.