Back to IOS

After spending two years in Information Assurance and cybersecurity policy, it’s time for me to get reacquainted with the core routing and switching technologies that enable modern network security concepts.  What better way to restart my networking studies than by pursuing another Cisco certification?  And that’s the train of thought that ended with an Amazon Prime delivery of the Official Certification Guides for 300-101 (ROUTE) and 300-115 (SWITCH).  These books are just a little heavier than my CCNA texts, and I’ll be using real IOS images with GNS3 instead of Packet Tracer emulation on this go-around, but the learning process should be the same (if a bit rusty).

The first few chapters of the ROUTE Official Certification Guide (OCG) were largely reviews of basic CCNA topics such as IPv6, network design, and basic routing protocols.  Chapter 4 introduced fundamental EIGRP concepts such as neighbor relationships and EIGRP verification commands.  The lab topology was simple – just three routers with serial interconnections and five subnets connected via fast ethernet ports – and the configuration commands were equally simple.

Fundamental EIGRP Topology

Setting up EIGRP is almost trivial:

router eigrp 1
   network 10.0.0.0
   network 192.168.9.0

This quick three-line snippet is all that is needed to run EIGRP on all R1 interfaces: Fa0/0, S1/0, and S1/1 (in the 10.0.0.0 classful class-A network) and Fa0/1 (in the 192.168.9.0 classful class-C network). Adding a wildcard mask such as 0.0.31.255 after the IP address in the network statement allows for more elegant deployment of EIGRP by classless subnets rather than classful A/B/C networks.

Finally, the chapter reintroduced five key EIGRP verification commands – show ip eigrp interfaces, show ip protocols, show ip eigrp neighbors, show ip eigrp topology, and show ip route. Each of these commands displays a different set of information about the EIGRP configuration, including hello and hold timers, passive interfaces, and metric weights (K-values).

None of the material in this chapter was earthshatteringly new or complex, but I will definitely need to commit the verification commands to memory – if my previous experiences are any guide, show run will not be an option on the ROUTE exam!

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