I saw an oldest thread that netflow is not supported on any of catalyst 2960/3560/3750. Has there been any change today?.
What about 4510 with 6-E supervisor?.
Yes, Cisco has still not introduced NetFlow support on the old Catalyst models like 2950, 3560 or 3750. The best option you have is to mirror the port on these devices and connect that port to a NetFlow supported device and export NetFlow from that device. You can then monitor this NetFlow data to get reports on the traffic through the unsupported device.
If you cannot afford another device just for this, you can add a server and install some open source flow generators like nProbe or fProbe. These tools will generate and export NetFlow data to any analyzer tool which can then generate reports. I have seen a number of people use nProbe or fProbe in such a setup with ManageEngine NetFlow Analyzer.
As far as I have heard, SUP 6-E does not have NetFlow support. You either need to add a NetFlow daughter card or move to SUP 10-GE which has NetFlow support by default.