DDMS

Device Discovery and Mobility Service (DDMS) is a windows middleware application that tracks the presence (online/offline) and mobility (site and channel) of radios on a MOTOTRBO system. Introduced in system software release R2.3 to replace the legacy MOTOTRBO Presence Notifier (PN), DDMS processes Automatic Registration Service (ARS) messages sent by radios and shares this availability and routing data with connected applications like Radio Management, Dispatch, and IMPRES Battery Fleet Management. By providing this routing information, DDMS allows data applications to send messages directly to the repeater where the target radio is located rather than broadcasting across the entire network.

The DDMS settings in Radio Management Device Programmer.

Operation

DDMS operates as a data link between the MOTOTRBO infrastructure and voice/data applications through the following mechanisms:

• When a radio powers on, changes channels, or roams between sites, it transmits a registration datagram (known as ARS) over the air using UDP port 4005. When received by a Control Station or MNIS, this ARS message is passed to DDMS. DDMS registers the radio as Present and returns an over-the-air acknowledgment. If a radio powers off, deregisters, or fails to send a periodic refresh message (default is every 4 hours), DDMS updates the radio's status to Absent.
• When deployed alongside MNIS (MOTOTRBO Network Interface Service), DDMS records the site, channel, and timeslot where the source radio's ARS message was received. MNIS subscribes to this mobility information and uses it to build a dynamic IP routing table. As a result, outbound data packets (such as Over-The-Air Programming (OTAP)) jobs, text messages, or location poll requests) are transmitted only on the site; channel and timeslot where the radio is at.
• Applications that require subscriber status information are referred to as Watchers. Watchers connect to DDMS over TCP/IP and subscribe to presence or mobility updates for specific Radio IDs or ID ranges using a documented API. DDMS immediately responds with the current status and IP address of each requested radio, and subsequently sends automatic real-time notifications whenever a radio's status changes.
• In Conventional, IP Site Connect (IPSC), Capacity Plus Single Site, and Capacity Plus Multi-Site systems, a single DDMS instance can maintain states for up to 400 radios and process up to 10,000 subscriptions across 25 simultaneous Watcher applications. DDMS can be installed as a standalone Windows service or deployed on an Edge Node.

Not required in Capacity Max

Standalone DDMS software is not required or installed in Capacity Max trunked systems. Instead, DMR Tier 3 native registration is managed directly by the Trunking Controller on the Capacity Max System Server (CMSS), which has its own native Presence Notifier interface on TCP/UDP port 50015 (CMSS Site Base IP +1) for Watcher applications.

Passive Mode

If you deploy a MOTOTRBO application (such as Radio Management OTAP) alongside a 3rd-party presence application using Control Stations, DDMS can be configured to operate in Passive Mode. In this configuration, DDMS and its associated Control Stations (or MNIS configured with an ARS Monitoring ID) monitor over-the-air ARS traffic passively without transmitting over-the-air acknowledgments. This allows the 3rd-party server to send the required over-the-air ACK while DDMS still updates its presence and mobility tables, preventing over-the-air packet collisions.

If any radios have ARS enabled but DDMS or MNIS is offline or unreachable, the radios will attempt to register 5 times in rapid succession before falling back to retrying every 30 minutes. On a large system, hundreds of unacknowledged radios retrying simultaneously will heavily saturate the system channels. To prevent this, one should always verify that DDMS and MNIS services are running and reachable before turning on a large fleet of ARS-enabled radios.

When scheduling large Over-The-Air Programming (OTAP) jobs in Radio Management, if the configuration update does not modify channel or zone assignments (e.g., updating button functions or contact aliases), tick the Suppress ARS after Switchover box in the schedule Job popup window of the Radio Management client. This prevents hundreds of radios from simultaneously flooding the network with ARS registration attempts immediately upon rebooting after the write job completes.

See Also

• MNIS
• Control Station
• ARS