NGSI LD does not seem to define or implement "/op/notify", which was the endpoint of "Context Broker Federation" implemented in NGSIv2.
Is there an equivalent function in NGSI LD?
■ manual
■ Spec
Orion-LD does not implement federation yet. The concept is being defined in ETSI ISG CIM and until it is decided exactly how it is to work (in a standard way), it cannot be implemented (unless we're willing to reimplement it once it gets defined in ETSI).
That said, Scorpio (another NGSi-LD broker) implements its own "NEC proprietary" federation scheme.
About "/op/notify", it is actually implemented in Orion-LD (POST /ngsi-ld/ex/v1/notify), it's just not meant for federation but for maintaining a local copy of some other broker's entities, based on subscriptions/notifications. This feature in brand new and was added to Orion-LD a few weeks ago.