ASICs

- "show asic-version slot x" will show the count of ASICs like Rohini (Port ASIC), Janus (Fabric interface)

Took it from here.
There is no oversubscription built in to the Rohini-Janus interconnect. The oversubscription on these cards is from janus to the fabric. Also intra Janus there is a 26Mpps limitation.

To elaborate, 6748-GETX is as you say, 1-12, 13-24, etc. The port mapping for the fiber version of 6748, and for 6724, is a bit different, it is even & odd (so eg, 1-23 odd, 2-24 even, etc) but yes it is 12 ports per rohini in all cases.

WRT oversubscription, again, the oversub is at the fabric level, not the port level as you would see on some 4500 series cards & on the 6500 series 6148-GETX etc.