atures The Catalyst 3750 switch is the next step in the evolution of the very popular 3550 fixed-configuration switch. The 3550 was the first multilayer switch offered at its price to boast such a vast array of features. It was later succeeded by the 3560. The 3750 is a more powerful switch that introduced, among other things, a true stacking feature, which the 3560 lacks. There is not enough room to cover all of the capabilities of the 3750 in one chapter, SO I've focused on those features that I have found most useful in the field. I've purposely not included all the gory details of each feature discussed. Instead, I've covered what I believe you'll need to know to take advantage of these features. Not all of the features I'll discuss are specific to the 3750. The commands may be identical on other models, but this chapter specifically includes examples taken from the 3750. As always, Cisco's documentation covers all the features in detail. Stacking One of the major shortcomings of the 3550 and 3560 switches is the way they are stacked. Stacking refers to linking together multiple switches, usually of the same type, to form a single logical switch with a single management IP address. Once you telnet or SSH to the IP address, you can control the stack as if it were a single device. The 3550 uses a stacking design that requires modules called stacking GBICs to be used in one of the gigabit GBIC slots. This not only limits the stacking backplane speed to 1 Gbps, but also ties up the only gigabit slots on the otherwise 100 Mbps switches for stacking. So, when you stack your switches, you can no longer connect your uplinks at gigabit speeds. The 3560 uses a special SFP interconnect cable. It is available with 10/100/1000 RJ-45 ports, but using the stacking cables still occupies one of the fiber uplink ports. The 3750 uses a more robust approach, incorporating special stacking cables that con- nect to the back of the switch chassis. This backplane connection is 32 Gbps (or higher, depending on model) and does not tie