The following quote appears many times in the docs, starting back about 5 years ago. I know that the switches that are being dissed are end-of-life.
Note If you are using a Cisco Catalyst 4000 Series Switch as the main router in the network, ensure that it contains, at a minimum, either a Supervisor Engine 2+ (SUP2+) or Supervisor Engine 3 (SUP3) module. The SUP1 or SUP2 module can cause roaming delays, as can the Cisco Catalyst 2948G, 2980G, 2980G-A, 4912, and 2948G-GE-TX switches.
My question is what specific characteristics make a switch good or bad for roaming? This might be useful, for example, in putting together an RFQ document. But what is the specification that new Cisco switches are better at than the old ones? Or is the question about gear so old and crufty that the answer is lost and only Harrison Ford can get it back? [Can I put Harrison in an RFQ?]
An RFQ for switches. RFQs are based on specifications. What is the specification and how do you state it? There is something wrong, deficient or defective about the old switches? What is that? What did the old switches do wrong that made them "not good." Cisco never seemed to give the basis of their recommendation that I quoted. My question is whether anyone knows what, specifically, they were talking about.
I am the first to admit that this question is out of the mold of what is normally posted here. I don't want advice on how to make something work. I want advice on why Cisco said what they said.