I work for the Purdue University Data Network. We are a campus with approximately 25,000-30,000 active network jacks. Here, we use Cisco switches exclusively. Our network core mostly consists of Catalyst 6000-series and 5500-series switches, with smaller Catalyst 2900's, 3000's, and increasingly more 3500's at the edge.

When you combine the setting of a large campus and Cisco's switches you get a very powerful, efficient, and scaleable network.

In our case, our network has deployed the 2900XL series switches at the edge and in some small workgroup settings. The 2900XL's base configuration is a 24-port 10/100 copper switch. We have configured most of ours with a dual additional 100BaseFX fiber module in each switch, but a 2900XL has two module slots -- one of them typically occupied by the dual 100BaseFX module, and one available for future expansion 10/100BaseTX cards. This setup is extremely versatile for us, especially when the solid set of management features are put to use.

The C2900XL's sit in at least roughly 40% of our 430+ closets around campus. In any given closet we can configure the switch as an uplink provider for more than two dozen 10/100Mb users or as an aggregation point for several older Catalyst 3000 switches for mid-size, low-speed buildings. In most cases the C2900XL can easily accomodate building loads where we have at least 800 10mb users and four subnets. Trunking and VLAN's are set up effortlessly, on a per-port basis, to an uplink provider or on the downlink.

Other management features are over my head, but the sheer number of command line options available even in non-enabled mode are quite numerous. Getting a quick overview of the switch's status can be done with a multitude of "show" commands. My favorite must be "sh int status", which is an abbreviation to show the status of the interfaces on the switch. Fa0/1-24 are the 24 10/100T ports, while Fa1 and Fa2 are the expansion modules. This command gives you a very easy way to get an at-a-glance look at what the interfaces on the 2900XL are doing and how things are working. There are hundreds of other available commands, but I have only used a few.

With hundreds of different VLAN's on our campus it is obvious that we need a solution that works smoothly and integrates subnets without a hitch. The 2900XL can do this all transparently, of course, when used with any device of your choice. In our case, we can take trunks from the 3000 series switches at the far edge, assign a certain VLAN (subnet) to any individual port on the switch, which is useful for uplinking hubs or just changing a user's subnet on the fly. The 2900XL is a workhorse at funneling all of that cool stuff into one, two, three, or even four 100BaseFX fiber uplinks to our core. The four interfaces can be combined or aggregated in some way for bandwidth-hungry deployments, yet I am unfamiliar with how this works or if I have actually seen it work, but I know it does have some load balancing abilities.

Overall, the Catalyst 2900XL is a vital component of our huge campus core. Even though they use at least 2U of rack space and are quite a beast, they outperform their higher-numbered 3000 counterparts. Our campus' migration to Gigabit-IDF-BDF strategy means that the 2900XL will soon become legacy with us replacing them with the 3500 and 2548 series of 1U switches. Twice the capacity in half the rack space makes the newer Catalysts a quick adoption by the University. But the 2900XL will still be working hard, and lets our senior network engineers sleep at night.


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