IPSC3 supports authenticated OpenBridge DMRD trunk links. Each voice or data packet is authenticated with the trunk's configured HMAC-SHA1 passphrase, and talkgroup routing remains controlled by the normal IPSC3 talkgroup and trunk mapping settings.
Standard OpenBridge trunks exchange authenticated DMRD packets without a separate control-plane heartbeat. Leave Enhanced OpenBridge disabled when the remote system expects this behaviour.
Some FreeDMR and RYSEN systems require the Enhanced OpenBridge control plane. Enable Enhanced OpenBridge (BCKA/BCSQ) in the trunk editor for those links only.
OpenBridge group traffic is opt-in per talkgroup and per trunk. IPSC3 accepts
or transmits a group only when that trunk has an explicit enabled row on the
talkgroup configuration screen. Inbound trunk mapping is applied first, so a
remote number such as 5055 can map to an enabled local group such
as 69159.
Unknown talkgroups and groups not enabled for that trunk are discarded before active-call publication or fanout. They therefore cannot appear as live local activity or be relayed to repeaters, hotspots, POC clients, or other trunks. Private and data-call routing remains separate from this group allowlist.
A BCKA packet is 24 bytes: the four ASCII bytes BCKA, followed
by the 20-byte HMAC-SHA1 digest of those four bytes using the same passphrase
as the OpenBridge DMRD link.
A BCSQ source-quench packet is 31 bytes: the four ASCII bytes
BCSQ, the 3-byte destination talkgroup, the 4-byte stream ID,
and the 20-byte HMAC-SHA1 digest of those first 11 bytes. IPSC3 uses bounded
in-memory stream state for BCSQ; it does not add database work to the voice
packet path.
Source quench is used when an inbound group is not enabled for the trunk and when a duplicate copy of an existing trunk stream arrives over an Enhanced OpenBridge link. Received quench state expires after 180 seconds as a safety bound against missing terminators or reused stream state.
Enabling Enhanced OpenBridge adds control-plane presence and source-quench handling. It does not change DMR audio payloads, packet pacing, talkgroup mappings, caller IDs, or trunk-to-trunk policy.