Hello ncp,
classic linecards can connect at 6 Gbps per direction to the backplane
linecards with final E at 24 Gbps per direction
the supervisor has its own capability.
the backplane overall figures are counted twice: they sum tx and rx rates this is done by all vendors.
here is a link for supervisor comparison
http://www.cisco.com/en/US/products/hw/switches/ps4324/prod_models_comparison.html
to be noted if you have the normal linecards they are limited to 6 Gbps per direction whatever supervisor is in use.
So there are linecards with 48 GE ports and a ratio 8:1 that make them not good for server farms
show platform health
has a section where it shows current BW usage per slot
Hope to help
Giuseppe
