The OpManager WAN RTT Monitor monitors the latency between two locations using Cisco's IP-SLA, therefore either of the locations should have the Cisco router enabled with IPSLA agent which will act as a source and the target can be any IP in the other location(Need not be a cisco router).
We recommend using a Cisco networking device as the destination device although any networking device that supports RFC 862, Echo protocol, can be used.
For more information :
https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipsla/configuration/15-mt/sla-15-mt-book/sla_icmp_echo.html
