1, 2, 3 or More - How Many Cisco Switches in Your Lab?

When building a lab to use to practice for CCNA or CCNP, you need Cisco switches. Part of the decision must be how many switches you can afford. And of course you'll want to know whether adding that extra switch really helps you study and practice, or not - and that's hard to know until you understand the switching topics in a particular exam. Today (and the next several posts), I'll discuss the topology issues comparing the 1, 2, and 3 switch options, first for CCNA and then for CCNP.

The choice of how many switches, and which models, tends to give people a little more trouble than the similar decision about routers. Why? First, so unless you're relying on a Simulator, you'll need real switches. And there are plenty of features that require a 2nd switch for any meaningful practice - STP and VTP come to mind immediately - but then it's hard to know how much you need 2 or even 3 switches until you're pretty far into studying for CCNA. So let's start with a CCNA breakdown for a 1 switch and 2 switch topology, looking at features that can be practiced reasonably well in each case.

For both topologies, I would expect you to have at least 2 (preferably 3) other devices to drive traffic for testing. For CCNA, you need routers as well. So I'll count on your having two routers, and a PC from which to configure things.
If you look at all the CCNA switching topics, a lot of them can be done in a lab with a single switch. For example, for CCNA:

• basic administration and CLI practice (passwords, hostnames, banners)
• VLANs
• Interfaces (speed, duplex, auto-n)
• IP access to switch
• 802.1Q trunking with a router
• Voice VLAN
• STP portfast

But as with routers, there are several CCNA features that just can't be practiced meaningfully without at least two switches. Then, when you get to CCNP SWITCH and TSHOOT, there are several more. For instance, for CCNA:

• VLAN Trunking Protocol (VTP)
• Spanning Tree Protocol (STP)
• Switch-switch 802.1Q trunking
• Etherchannel

For CCNP, I can appreciate the fact that you may be forced to use a single switch for your lab, just due to cost. 1/3 of the core page count of the book focuses on topics like STP (and its many variations), VTP, trunking, Etherchannel, all of which need at least two switches. The bigger question for CCNP (in my opinion) is whether you spring for a 3rd or 4th switch, and whether you make any of those layer 3 switches. I'll get into the layer 3 tradeoffs in the CCNP lab series (next up in the list), but this 3-4 post series will look hard at the layer 2 features related to the question of adding a 3rd switch to a CCNP lab.

• Uses the same triangle design in most campus switch designs
• Allows configuration and meaningful testing of all CCNP STP features
• Much more interesting STP topologies for more meaningful practice
• More meaningful VTP experiments (eg, one each server, client, transparent)