Routers

As a Cisco engineer, you will spend a lot of time installing, configuring, and troubleshooting
routers. For this reason, over half of the CCNA syllabus is dedicated to learning all about router
configuration.
A router (see Figure 1.3) is a device used for networking. While network switches involve
devices on the same network communicating with each other, the router communicates with
devices on different networks. Older models of routers only had ports, which were physically
built into them and attached to the motherboard. This is still sometimes the case, but modern
networks now require a router to perform functions for IP telephony, switching, and security,
and to connect to several types of telecoms companies. For this reason, routers are also
modular, which means you have the router chassis and empty slots into which you can connect
a variety of routing or switching modules.


Figure 1.3 – Modular Cisco Router with a Blank Slot to the Right
The Cisco website has a lot of advice and information available to explain which router model
will suit your business needs. There are also tools which will help you select the correct model
and operating system. It’s well worth your time learning how to navigate the support and
configuration pages and bookmarking them for quick reference.
How Networks Are Represented in Diagrams
All network engineers need a common method to communicate, despite which vendor and
telecoms provider they are using. If I had to describe my network topology to you for design or
security recommendations, it would work much better if it were in an agreed format as
opposed to something I had drawn by hand from memory. The Cisco Certified Design Associate
(CCDA) exam is where you will learn about network topologies in far more detail. As for the
CCNA exam, you will need a basic understanding of these topologies because the exam may
present network issues and ask where you think the problem lies.
Here are the common symbols for network devices you will encounter in your work as a
network engineer. You can download these icons from the Cisco website if you type “Cisco
icons” in your browser’s search engine. We use either plain blue or color (for the Kindle
version). I’ve used a mix of the most common router and switch symbols throughout the book
so get used to the types you will see in network diagrams in the real world.



Routers

Switch (Layer 2)

Router with Firewall

Wireless Router

Multilayer Switch