[c-nsp] 6500 dbus usage

[Jon Marshall]

I thought i understood 6500 architecture but after reading some of the posts on here now am not so sure !
 
My understanding was you basically had - 
 
1) classic linecards - only connect to shared 32Gbps bus  eg. WS-X61xx/63xx
 
2) fabric enabled - connections to both shared bus and crossbar switch fabric eg. WS-X65xx 
 
3) fabric only - only has connections to switch fabric eg. WS-X67xx 
 
It's 3) i am confused about. The 67xx won't work with the sup32 and i always thought that was because these modules didn't have connectors to the shared 32Gbps bus and the sup32 only provides a connection to the 32Gbps bus.  
 
My confusion is when i read on here that when the 67xx modules are running in CFC mode they send a portion of the packet (depending on compact/truncated mode) across the 32Gbps bus to the supervisor for a forwarding decision to be made. But if they don't have connectors to the 32Gbps bus then how do they access it ? 
 
As a further question, assuming they do send lookups across the shared bus then having classic linecards using the same bus could have a direct impact on the performance of the 67xx modules ? 
 
Could someone clarify this please
 
Jon