I use a 7609 router to connect to 3 ISPs. Traffic monitored by PRTG v6 on 7609 sometimes go down and then up rapidly (pls see attach file) but traffic on interfaces of 3750 connected to 7609 don't suffer this phenomenon. All modules on 7609 are fabric enable and I use dCEF. I still don't know how to solve this phenomenon. I appreciate your advices!