I suspect that a significant percentage, if not a majority, of network administrators are sitting on switches that are a couple of years old; likely purchased during the dotcom craze. They're almost definitely 10/100 Ethernet, with plenty of ports for your users, and you probably already have Gigabit uplinks, but still, it's been a while, and you're thinking about upgrading. What should you do?
Justifying a switch upgrade can be extremely difficult. To be perfectly honest, it's rare for a user to get anywhere near capacity on Fast Ethernet. In fact, most users are good to go with 802.11b wireless, which more often than not is running closer to 5mb/s. And even in a campus with thousands of users, it's rare to see a Gigabit circuit in the core hit even 200Mb/s, much less 70% utilization. And the processor and memory categories aren't going to give you a lot of satisfaction either, unless you happen to have an e-mail worm running amuck.
Yes, even using the classic "3 year expansion" story, most administrators are going to have a tough time explaining why they need that new 500 Gb/s backplane. So why upgrade? If your network budget is burning a hole in your pocket, my advice is to spend your money where you'll get more bang for the buck, like security, or upgrading your WAN or internet circuits. But there are a few legitimate reasons to consider upgrading:
First, at some point, the likelihood of a hardware failure begins increasing rapidly. Most manufacturers offer credits for trading in hardware, and it's a good idea to take advantage of this before they're complete junk.
Second, there are a lot of recent features that can make an upgrade worthwhile. Most of these have to do with integrating IP Phones and Wireless Access Points. Examples are Power over Ethernet, "voice VLAN" support and 802.11x authentication. Also, hardware-level QoS support has matured in the past few years and is now worth doing in most switches.
Third, in server-farms, it's not impossible to make a case for a switch with high-density 10/100/1000 copper ports.
Finally, some chassis-based switches now support voice-gateways, firewalls, intrusion-detection and other features in a blade form-factor. Although this isn't for everyone, in some cases, integrating these into your switch can justify an upgrade.
Tom Lancaster, CCIE# 8829 CNX# 1105, is a consultant with 15 years experience in the networking industry, and co-author of several books on networking, most recently, CCSPTM: Secure PIX and Secure VPN Study Guide published by Sybex.