|Network Warrior: Everything You Need to Know That Wasn't on the CCNA Exam|
|author||Gary A. Donahue|
|summary||A practical look at what you really need to know to run a Cisco network|
The CCNA exam is supposed to test a candidate's understanding of networking fundamentals. Over the years it has expanded to include more advanced material, and now covers networking theory, switching (including spanning tree and VLANs), and some of the intermediate routing protocols such as EIGRP and OSPF. Despite the breadth of content the exam doesn't (and can't) cover things that many network folk take for granted, even things like what the "demarc" is (short for demarcation point, the the place where the carrier's responsibility ends and yours begins). While the exam's topic list is broad, the level of detail is shallow in most places. Someone may study spanning tree enough for the exam, but have no clue where to place their root bridge when they get into the real world.
It is for this reason that I found Network Warrior to be helpful. It's goal is to point out both the technical areas in which the CCNA falls short, and to teach the reader the non-Cisco aspects of running a network.
Technically I found this book quite sound. There were a few things one might disagree with but nothing that detracted from the rest of the book. In several spots the author was keen to point out behaviors that deviated from the documents, such as in Quality of Service (QoS) and in upgrading certain modules in the 6500 chassis. He also illustrated where the theoretical concepts on network design fall short in the real world.
Routing and switching takes up the first third of the book. The switching section is largely a review of the CCNA material with some notable exceptions. First and foremost is a chapter exclusively on autonegotiation. The CCNA exam may only discuss how to set a port to a fixed speed, but anyone who has worked with a network for more than a few weeks will have run into a speed or duplex mismatch. This chapter explains some of the history behind Ethernet and its relevance to autonegotiation, explains how it works, how it fails, and how to recognize the problem, and finally offers advice on when and where to use autonegotiation.
The second major deviation from the CCNA switching syllabus is in depth coverage of Etherchannel and spanning tree (STP) Both of these protocols are integral parts of network design and operation, but the exam barely touches Etherchannel and doesn't get into the complexities of spanning tree (though this changes with each iteration of the exam.) Network Warrior provides techniques and a demonstration of finding a layer 2 loop. Surprisingly though, there is only mention of standard 802.1d legacy spanning tree and some Cisco extensions such as Per VLAN STP and backbone fast, and no mention of the newer standardized enhancements of 802.1s/w (rapid spanning tree and multiple spanning tree) which have been in common use and have been put on the latest version of the exam (released after this book went to press)
The third deviation is the inclusion of CatOS commands instead of just IOS like the exam. As the author repeatedly points out, CatOS is in use on many 6500 chassis and is still in active development, so there is no reason not to know it. This theme continues throughout the book whenever the 6500 is used as an example, which is often.
The routing chapters are full of new material. The sections on the routing protocols themselves are short and don't add much beyond what the CCNA certification teaches. Redistribution and route-maps, however, are well explained. These two technologies which can be used separately or together can be found on almost any network and are very complex. I thought these sections were well done, as they gave enough details to be practical without getting down into all the different scenarios. Tunnels make an appearance in these chapters, which themselves aren't very complex, but aren't a part of the CCNA blueprint.
At this point, roughly page 180 of 550, the rest of the material isn't found in the CCNA blueprint.
Part 3 of the book is all about multilayer switching, specifically the 3750 and 6500 platforms. In particular the description of the 6500 architecture is much more succinct that can be found by searching on Cisco.com. There is an in depth explanation of how the various backplanes on the chassis works, which leads to an explanation of how to determine which cards are slowing down your switch.
I think the hidden gem of the book is part 4, though, which is all about telecom. In these chapters are an explanation of how carriers operate and how to speak the lingo of telecom techs. Even though networks are moving to Ethernet based services, traditional DS1, DS3, ATM, and frame-relay networks are still commonplace. The book has a solid explanation of how TDM based circuits actually work, the various options available to you, and how to properly order and troubleshoot them. I think back to when I was getting started in this field, and dealing with carriers was difficult.
Quality of Service, the features that let you guarantee and limit bandwidth to different types of traffic, have a section in this book too. The book largely focuses on the simple weighted-fair queuing (WFQ) and the current class-based WFQ with low latency queuing for voice. Configuration instructions can be found on Cisco's site easily enough, but Network Warrior delves into some of the behavioral aspects the documents shy away from such as when the queuing mechanisms actually get used. There is also a solid look at how to make sure the QoS is working as intended.
In the middle of all of this are chapters on the firewall and load balancing modules for the 6500, the PIX firewall, and IOS based load balancing. For someone with an ecommerce slant these might prove helpful, but given that these topics are books in themselves, it's hard to do them justice in a few chapters.
The last part of the book is on network design, which encompasses not only the steps needed to build a network, but also planning IP address allocations and how to pitch your ideas to management. Again, the book is not trying to be the definitive text on the subject, but it manages to impart a few words of wisdom, especially the so-called "GAD's Maxims", and "How not to be a computer jerk".
Well thought out examples were plentiful, along with anecdotes from the author, usually showing the consequences of doing things wrong. The illustrations did a great job of conveying the point at hand. Even though I've been doing this stuff for a while I learned several time saving techniques that I've already been able to put to use.
This is a great book for people just getting into the industry, with their CCNA or without. It offers practical advice rather than dry textbook like explanations which is a welcome change. Even those with a few years of experience under their belt will be happy reading through Network Warrior.
Sean Walberg is a network engineer and author living in Winnipeg, Canada.
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