I'm looking at a 6509 on a site where the client manages their own LAN but are having problems. I have found several interfaces to be in Up/Down status and one of them was incrementing significant Output errors with collisions nearly matching total packets. The client says they've disconnected the SFP on site (I'm remote), but the Interface status remains Up with protocol Down and the interface counters continue to increment. If I clear counters, I'll see 0 input and output packets, and then the next time the counters update it's back to 4 billion + for each. The only way I've seen packets pause on the interface is to go admin down. Any suggestions on how an interface with no media is somehow incrementing packets.
