Please advise me the technical cons of the sentence in layman's terms:
"Cisco's WS-X6148-GE-TX on Core C6509 is heavily oversubscribed (8:1). Also it connects only to the 32Gbps shared bus."
Many thanks for the compliment and rating.
I'll try and explain the 8:1 ratio in a bit more detail. The WS-X6148-GE-TX has an 8:1 oversubscription ratio because it groups together 8 ports into a single ASIC. This ASIC (called a pinnacle asic) transfers data between the switching fabric and the network ports. There is a 1Gbps uplink from the ASIC to the switching fabric ie. the aggregate throughput of the 8 port group cannot exceed 1Gbps.
So you have 8 network ports that can each have a device supporting 1Gbps which only have a 1Gbps connection to the switch fabric. This is why you are oversubscribed and that's why the WS-X6148-GE-TX is primarily for the wiring closet where you expect some level of oversubscription.
Contrary to what i said before it does look like the port groups of 8 are contiguous ie. 1 -> 8, 9 -> 16 etc.