5.1 R3 is sending 2 types of Hellos
The default hold time is three times the hello interval, or 15 seconds.
For slow-speed NBMA networks, the default hold time is 180 seconds.
This is because FR cloud is served by the ISP.
It is not our own property.
If we send so many Hellos through the cloud, it costs us a lot.
This is the reason why we sustain so many Hellos compared with non NBMA networks.