Need help with Heavy Forwarders stop sending data or a significant drop in it's data sending (5-10% drop of total amount

[SamHTexas]

Please help with an SPL or use MC to see if / when a HF stops sending data or there is a big drop in the amount of data it usually sends like 10% of the normal data sent. How do I tell if a HF is sick & not functioning? I appreciate your time in advance. Thc