I want to use OpenNMS and test Linkd layer 2 iso/osi model network topology discovery. But I can't find linkd daemon after starting OpenNMS, and there is no configuration file linkd-configuration.xml. The instruction page is https://www.opennms.org/wiki/Linkd
Linkd was removed in OpenNMS Horizon 16. The new daemon is Enlinkd (enhanced linkd). You can find the configuration in etc/enlinkd-configuration.xml. It is similar to the old linkd configuration. see notes at https://www.opennms.org/wiki/Map_Use_Cases_2015#Linkd_and_EnLinkd
Don't forget to enable the Enlinkd daemon if it isn't in service-configuration.xml.
I've also updated the Linkd wiki page with a note.
The configuration for the "Enhanced Linkd" daemon can be found here: http://docs.opennms.org/opennms/releases/17.1.1/guide-admin/#ga-enlinkd