over subscribing an interface would mean for example:
a frame relay speed of 512k is configured with 4 256K CIR PVCs. this link is now oversubscribed by 512k. this is ok due to the nature of frame relay.
this is also ok with CBWFQ. CBWFQ would be impacted though as providing most of the available, if not all, bandwidth to the classBased prioritized traffic.
in other words, CBWFQ will do it's job and assure the class prioritized traffic gets processed first. there may still be drops of packets, even if CBWFQ is operational, as the link is oversubscribed and at that point, most if not all packets are discard eligible if there is no bandwidth available.
