I've been looking at switches that have a total of 48 10 Gigabit ports and the closest I got was the 4900M which has 8 fixed and expansion slots where we can put 8-port module cards on each, so this way I can total 24 10 Gigabit ports.
I need a chassis, in other words a single unit, that has a total of 48 10 Gigabit ports. Is there such a monster?
If not, can I purchase those 10 Gigabit modules SUPs and put them in the 6500 or 7000 series switches to come up with a total of 48 10 Gigabit ports?
"Bottom line is then I want to stay away from oversubscription?? "
Often not, it depends on usage. Some oversubscription can be fine as rarely do all ports run at 100% for 100% of the time. When such links have more traffic then they can handle, it's queued or dropped, but even then, QoS can determine which traffic might be delayed/dropped or not. Much depends on how you'll be using these ports.
"what do you mean by oversubscription? "
Since a 6500 provices 40 Gbps per slot, but there are 4, 8 and 16 port 10 gig cards, card port bandwidth to card slot bandwidth ratios are: 1:1, 2:1 and 4:1; more than 1:1 is oversubscription (i.e. the slot can not run all ports concurrently at full port speed).
"what's the smallest (in physical size) switch I can get in order to total up 48 ports? and what are the exact cards/modules I should get for those?"
Probably the 5020 Nexus would be the smallest. Next smallest might be a 6504 with 3 16 port 10 gig cards and a sup720.