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6
Routing
Cisco expects CCNAs to demonstrate a comfortable understanding of the logic behind the
routing of packets and the logic behind a routing protocol. This chapter focuses on
routing
protocols
, the protocols used to discover routes. To fully appreciate the nuances of routing
protocols, you need a thorough understanding of routing (the process of forwarding
packets). If you have not yet reviewed the section on Layer 3 in Chapter 3, "OSI Reference
Model & Layered Communication," and the sections on IP and IPX in Chapter 5, "Network
Protocols," then you might want to review those sections before proceeding with this
chapter.
The CCNA exam requires you to know the nuances and details of distance vector logic,
which is covered in the first section of this chapter. This is the logic used by the Routing
Information Protocol (RIP) and Interior Gateway Routing Protocol (IGRP), as well as IP
RIP. In fact, some distance vector concepts even are applied to the NetWare Service
Advertising Protocol (SAP), even though SAP does not distribute routing information.
Along the way, alternative routing protocol algorithms (link-state and Diffusing Update
Algorithm [DUAL]) are mentioned briefly.
Implementation details of RIP (Version 1 and Version 2) and IGRP are covered next.
Because EIGRP configuration is similar to IGRP, it is also covered briefly. As you'll find
on the CCNA exam, knowledge and skills for routing protocol configuration and
troubleshooting are topics required of CCNAs.
Implementation of IPX RIP and SAP is another topic for which Cisco expects CCNAs to
be prepared. The flows required to connect a client to a server, including the Get Nearest
Server (GNS) protocol, also are important when troubleshooting IPX problems. As
mentioned in the introduction and Chapter 1, "All About the Cisco Certified Network
Associate Certification," Cisco definitely wants to reward CCNA candidates who have
good hands-on troubleshooting skills; knowledge of connection sequences for IPX and IP
is vital for being ready for any unexpected questions.
How to Best Use This Chapter
By taking the following steps, you can make better use of your study time:
·
Keep your notes and the answers for all your work with this book in one place, for
easy reference.
ch06.fm Page 353 Monday, March 20, 2000 5:11 PM