How to find out from which ip-addresses there is the greatest load on the channel?

Question

NetFlow

Please help me to figure out from which addresses there is the greatest load on the channel.
The situation is as follows:
Clients 172.16.17.0/24, which are located behind Cisco 4507, will be pulled onto the border Cisco 3925 (1) and exit under the address 192.168.0.254; these are the features of the network architecture.
All necessary services are on the 10.1.2.0/24 network.
The channel between Cisco 3925 (1) and 3925 (2) is only 1Mb / s and began to sag very badly.
Experience and knowledge are not enough to see exactly which machines (or services) on the 172.16.17.0/24 network load the channel between Cisco 3925 (1) and Cisco 3925 (2).

Answer 1

3925(1)
int gi0/1
ip flow ingress
ip flow egress
ip flow-top-talkers
top 50
sort-by bytes
Where Gi0/1 is the interface where Cisco is connected 4507
see the result with the command
sh ip flow top-talkers