CCNA Lab Part 8: How Many Switches, and Which Ones?

The Last Post in this Year's CCNA Series

It's time to wrap up (hoorah!) this spring's foray into the question of what to put in your CCNA lab. I hope that you've found the series useful. Today, I'll touch on a few final points with switches, looking at two questions. First, how many do you really need for CCNA study, and can you mix the switch models?

How Many Switches

The short answer is that you need 1, could really use 2, get some benefit from 3, and 4 or more is probably overkill. All that is my opinion, but it's worth some discussion.

First, I hate to repeat what's already easily read elsewhere, and I did actually write about this very issue in early 2010. The CCNA exam hasn't revved since that time, so all those comments still apply. But let me summarize the main points here in one place:

With 1 switch, you can practice:

  • 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

With a 2nd switch, you can then also practice:

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

Then, with a third switch, you can also practice:

  • Much more interesting STP topologies for more meaningful practice
  • More meaningful VTP experiments (e.g., one each server, client, transparent)

Basically, the big hitters are that a 2nd switch gets you VTP and STP, and a 3rd switch gets you more meaningful STP, because STP with just two switches is pretty dull. But you can do it - check out yet this other post, specifically about how to do STP with a pair of switches.

So, back to the main topic: how many switches should you buy? Well, you do get a big bump in benefit to get at least one, a pretty good bump in benefit to get a 2nd, a little more benefit to get a 3rd, and then pretty much diminishing returns after that. (I'd probably say buy another router before getting a 4th switch, for instance.) The sweet spot is to get at least 2, possibly 3 switches.

2950, 2900XL - But Can I Mix Them?

Last time out, I suggested that the best switch model today, all things considered, was likely the 2950 with standard software image. That gives you command syntax and features very close to switches you would buy today, and the price is pretty low ($50ish US) in our admittedly conservative price checks. But, if you really want to save some cash, the 2900XL series, older, some command differences, and some feature differences, is a cheaper option as well.

To be honest, I almost didn't go here in the post today, ignoring the question. I don't have a 2900XL in my lab, so any comment I make here about it is from reading, not doing. But since I brought it up, at least take what I write here with a grain of salt. If you've used both 2950 and 2900XL in the same lab, and want to comment, I'd love to hear.

The 2900XL models support 802.1Q trunking, and so does the 2950. The big deal there? VTP does not work at all without trunking first working. STP can be interesting without VLAN trunking, but it is much more interesting with it working. So, the biggest hurdle to mixing these two particular models does not appear to be a big deal.

It does appear that you would not have any 802.1W RSTP support on the 2900XLs, but like anything when building the lab, sometimes you have to lose a little to save some cash.

Final Thoughts

So, what's the perfect world? Get two or three 2950s. If the budget does not allow, get one 2950, and at least one 2900XL. (Hey, at $20, it's not that big a risk!) And get in there and try some configs!

That's all I plan to do for this year's CCNA lab series. Last chance to jump in before I move on to something else!

Related Posts:

CCNA Lab Series 2011: Overview

CCNA Lab II: How Topologies Drive Device Choices

CCNA Lab III: Sifting Through the Router Model Series

CCNA Lab IV: Choosing the IOS Version and Feature Set

CCNA Lab V: Ruling Out (or In) 2500 and 2600

CCNA Lab 6: The Best Router for CCNA, 2011

CCNA Lab 7: Choosing the Right Switch Models

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