As we have ping for IP, we have ndnping for NDN. It is used to measure RTT, but instead of using ICMP Reqquest/Reply packets, ndnping uses Interest and Data packets. The use of ndnping is simple on NDNx routing daemon:
Start ndnpingserver (producer side):
$ ndnpingserver ndn:/ndnx/ping
Start ndnping (consumer side):
$ ndnping ndn:/ndnx/ping
Notice, you should start server side. In IP world, we don’t have to do it because the stack in the kernel already knows what to do when receiving ICMP packets.
The command ndnpingsever will produce content for each arrived interest. Interests are sent by ndnping with a random sequence number to indicate a new and different interest.
When ndnpingserver receive an interest, the server copy the sequence number from interest packet into content packet. So, in this way, ndnping (client side) is able to know if the request was or not satisfied. In other words, if there is a connection to producer or not.
Hope helped you.