The 7500 platform use the VIP (Versatile Interface Processor) for WAN interfaces. When dCEF is active the actual processing of the packets is done by these interfaces. Each one has its own CPU, memory, etc. The troubleshooting of this VIPs is difficult from the main IOS. In order to gain access to a deeper level you can access the hidden "console" of each VIP.
The hidden command for this is "if-con X" where X is the position of the VIP. There you will have a subset of commands only related to the VIP hardware itself. Under that CLI you may also run the also hidden command "sh process cpu" or "sh process memory" which will inform the processes and memory utilization related to the VIP itself.
