Limitations
From 3GPP TS 23.007, Section 20: It is recommended that GTPv2 Echo Request should be sent only when a GTP-C entity has not received any GTP response message for a previously sent request message on the GTP-C path for, an implementation dependent time period.
Currently, this is not supported.
Even if SMF receives GTPC echo req from peer, it is considered as path is up. The subsequent Echo Req from SMF is received after the echo interval expiry.