CCNP Enterprise Certification Study Guide: Implementing and Operating Cisco Enterprise Network Core Technologies

Exam 350-401

Ben Piper

• Publisher: Sybex
• Year: 2020
• ISBN:
  9781119658801
• Edition: 1
• Topic: Informatik
• Subtopic: Zertifizierungsleitfäden in der Informatik

The practical and conceptual knowledge you need to attain CCNP Enterprise certification

From one of the most trusted study guide publishers comes CCNP Enterprise Certification Study Guide: Exam 350-401. This guide helps you develop practical knowledge and best practices for critical aspects of enterprise infrastructure so you can gain your CCNP Enterprise certification. If you're hoping to attain a broader range of skills and a solid understanding of Cisco technology, this guide will also provide fundamental concepts for learning how to implement and operate Cisco enterprise network core technologies.

By focusing on real-world skills, each chapter prepares you with the knowledge you need to excel in your current role and beyond. It covers emerging and industry-specific topics, such as SD-WAN, network design, wireless, and automation. This practical guide also includes lessons on:

? Automation

? Network assurance

? Security

? Enterprise infrastructure

? Dual-stack architecture

? Virtualization

In addition to helping you gain enterprise knowledge, this study guidecan lead you toward your Cisco specialist certification.

When you purchase this guide, you get access to the information you need to prepare yourself for advances in technology and new applications, as well as online study tools such as:

? Bonus practice exams

? Pre-made flashcards

? Glossary of key terms

? Specific focus areas

Expand your skillset and take your career to the next level with CCNP Enterprise Certification Study Guide.

Chapter 1
Networking Fundamentals

THE CCNP ENCOR EXAM OBJECTIVES COVERED IN THIS CHAPTER INCLUDE THE FOLLOWING:

• Domain 1.0: Architecture
  • ✓ 1.1 Explain the different design principles used in an enterprise network
  • ✓ 1.7 Differentiate hardware and software switching mechanisms

• Domain 3.0: Infrastructure
  • ✓ 3.1 Layer 2
  • ✓ 3.2 Layer 3

Forgetting the fundamentals is by far the biggest cause of failures—both network failures and failing Cisco exams. Just visit any networking forum and look at the posts from people who failed an exam by a narrow margin. Almost without exception, they can trace back their failure to misunderstanding or simply failing to learn fundamental networking concepts.

Networking fundamentals can at times seem abstract and even impractical. It's important to remember that networks are both logical and physical, so you need to keep a tight grip on both. If you neglect theory and just focus on typing in commands, you'll end up with a jalopy network. It might work, but not very well, and probably not for long. On the other hand, learning theory that you fail to put into practice leads to being educated but unemployed.

This chapter will give you a solid theoretical foundation on which to build practical skills. Much of the theory should already be familiar to you, and you'll likely have some “I already know this stuff” moments. But more often than not you'll gain new insights on something you already understood.

There's a lot of networking information out there, much of which is poorly explained, if not just plain wrong. Networking myths abound on forums, blogs, and even Wikipedia. Even official Cisco documentation has been known to contain the occasional errata. It's not intentional, of course. Learning networking is no different than learning any other complex topic. Some concepts are easy, whereas others just never quite click. Those harder concepts are fertile breeding ground for misconceptions that eventually get passed around until they become common knowledge, or worse, “best practices.” Almost every network professional I've encountered holds at least one glaring misconception about networking that eventually ends up stumping them (sometimes on an exam!). Chances are you, too, have been the unfortunate recipient of such information. The sooner we identify and dispel those myths, the better. That's what this chapter is all about.

The OSI Model

The origin of many networking myths can be traced back to the Open Systems Interconnection (OSI) reference model developed by Charles Bachman of Honeywell and formalized by the International Organization for Standardization (ISO). The ISO intended the OSI model to be a standard framework for data networks. It describes a set of “activities necessary for systems to interwork using communication media” (ISO/IEC 7498-4). The model organizes these activities or functions into the following seven layers:

• 7. Application
• 6. Presentation
• 5. Session
• 4. Transport
• 3. Network
• 2. Data Link
• 1. Physical

The seven layers are taught zealously in most introductory networking courses. You may have had them permanently drilled into your head with the help of one or two fun little mnemonics! (My favorite is “All people seem to need data processing.”) As we discuss the functions of the different layers, keep in mind that the layers of the OSI model are arbitrary. They're not written on stone tablets, nor are they the result of a rigorous scientific process that conclusively proved that the perfect network has these seven layers. The ISO arrived at each layer by attempting to group similar network functions together in a layer and then organizing the layers in a hierarchical fashion so that each layer of functions is dependent on the one below it. This led to impressive results in layers 1–4 (the lower layers) and utter confusion in layers 5–7 (the upper layers).

Table 1.1 shows what common protocols fall into each of the lower layers.

Table 1.1 The lower layers and their associated protocols

Layer	Name	Example protocols
1	Physical	Thicknet (10BASE5)
		Thinnet (10BASE2)
		1000BASE-T
		T1/E1
2	Data Link	IEEE 802.3/Ethernet II (DIX)
		Point-to-Point Protocol (PPP)
		High-Level Data Link Control (HDLC)
3	Network	IPv4
		IPv6
4	Transport	TCP
		UDP

The Upper Layers: Application, Presentation, and Session

One thing that has always been clear about the OSI model is that the Application layer includes application data and application protocols. The Hypertext Transfer Protocol (HTTP) is an appli...