Generally, the servers provide services to external parties over the Internet NIC. The intranet usage is usually low, unless when SLB is used (SLB communicates with ECS and intranet). The high intranet traffic is usually because other ECS servers are copying data to this server.
#yum install nethogs Install NetHogs
#nethogs eth0 View the specific traffic usage of the intranet NIC
With the help of NetHogs, you can see the specific intranet bandwidth usage and figure out which processes occupy the intranet bandwidth.
If you are using the system of Windows Server 2008 or later, you can go to the Resource Monitor to see the processes that occupy the bandwidth: