Traceroute is used when next hop is not available for SSH/telnet. Devices discovered using traceroute are marked as unmanaged in IP Fabric site diagrams. More information about traceroute as a protocol can be found on Wikipedia.
For traceroute configuration go to Settings → Advanced → Discovery → Traceroute settings.
Trace scope - limits traceroute scope to the defined subnets. This prevents scan networks outside an internal network.
RFC6890 - this button resets Trace scope setting to subnets defined in this RFC.
Protocol - the protocol used for traceroute can be selected from the options of ICMP (MS Windows like), UDP (Linux like), and TCP.
Port - in case of UDP and TCP, the destination port can be specified.