What is a BACnet Broadcast Management Device (BBMD)?

A BBMD is integral to BACnet/IP networks — but why?
What is a BBMD BACnet Broadcast Management Device

BACnet/IP predominantly communicates through broadcast messages, which are received by every device on the same network. Broadcasts are super important for discovering devices or finding and sharing new information. On big systems, though, you can’t have every device on every network sending and responding to broadcasts. If you broadcast to an entire system, it could bring the whole building network down. But sending individual messages from device to device would be overly complicated. 

Instead, we send messages between BBMDs. To put it simply, BACnet Broadcast Management Devices (BBMDs) act as a sort of forwarding service. They’re especially useful on large, complicated networks. A BBMD forwards messages from one subnetwork to another, so communications can be broadcast locally. No overwhelming the network, and no convoluted network of one-to-one communications.

How does it work? A BBMD (BBMD1) on one network receives a message from one of the devices on its network (network 1) that is intended for devices on another network (network 2). The BBMD has a database of IP addresses that tells it where to send that message. It forwards that message to the other network’s BBMD (BBMD 2), which broadcasts the message locally to its network (network 2). These diagrams from ControlsCourse illustrate the process nicely.

What is a BBMD BACnet Broadcast Management Device

What is a BBMD BACnet Broadcast Management Device

Here are three separate IPv4 networks, with devices that want to communicate across networks. Without a BBMD, they have no way of doing that: they’re blocked between their separate networks.

 What is a BBMD BACnet Broadcast Management Device

With a BBMD, however, the messages can be sent between subnetworks and distributed to the appropriate devices.

That’s the gist! For advanced readers, Contemporary Controls has some great technical info you can dig into. Note that you do not need a BBMD-specific device: many routers and controllers can act as the BBMD on a network.

It’s also important not to have more than one BBMD on the same subnet, as they will repeat all of the same information. If you’re struggling with duplicate BBMDs, check out our webinar on troubleshooting the issue:

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Recent Projects

Coventry University


Chris Goodman, the Senior BMS Technician at Coventry University, had broadcast storms that were happening more and more frequently. 

Ongoing construction due to Coventry’s campus expansion meant lots of new activity, with technicians installing new devices and making network changes. Already juggling these constant additions and alterations, Goodman and his small team then had to deal with the subsequent broadcast storms. As the broadcast storms became more frequent, Goodman and his team needed a solution.

Find out how Visual BACnet helped Chris solve the broadcast storms and improve Network Health in our free case study!

Data center expansion with OTI and Optigo Connect


Stack Infrastructure is a portfolio of hyperscale computing data centers. OTI completed work on Phases I and II, and returned for the Phase III build-out of a 4-megawatt data hall and brand new central plant. The Optigo Connect network put in place in Phases I and II was expanded on this project. The team achieved quick roll-out of a large, multi-service redundant network using the Optigo OneView management interface. Going forward, the facility management team can use OneView to remotely monitor equipment, manage power usage, and meet up-time goals.

Optigo Connect MR Soluciones The Landmark


The Landmark is a sophisticated mixed-use high-rise in Mexico. The owners wanted to integrate all OT systems in the skyscraper, while maintaining separate networks for each application. The Landmark is the fourth joint project between Optigo Networks and MR Soluciones. Together, these companies provide robust services to meet any challenge.

Australian Bureau of Statistics at 45 Benjamin Way with Delta Building Automation


Delta Building Automation (Australia) had a big job renovating the Headquarters for the Australian Bureau of Statistics (ABS) at 45 Benjamin Way. The building owner wanted to improve the building’s energy use and increase their National Australian Built Environment Rating System (NABERS) score to more than 4.5 stars, out of a possible total of six. Securing the network both internally and externally was a big priority, as well.

Penn State University Optigo Networks Visual BACnet


When Tom Walker looked at Penn State University’s Navy Yard network, he saw huge issues. The system was busy and loud, to the point where the overrun network was bringing down the entire building. Because this was happening on the MS/TP network, pinpointing the problem would mean boots on the ground to segment and test the chain, piece by piece.

Penn State University Optigo Networks Visual BACnet


When Tom Walker first started working at Penn State University four years ago, there were a lot of network issues. Buildings were dropping offline. Broadcast traffic was pushing 90,000 packets per hour. Walker was on the phone almost every single night because devices were down or had to be reset.


Torre Manacar Mexico City Optigo Connect


When MR Soluciones began work on Torre Manacar, they knew they needed a flexible and scalable network infrastructure to support a wide array of integrated systems. Optigo Networks was a natural fit for the massive project, designing a robust network at a competitive cost.



Short Pump Town Center, an upscale retail center, underwent a complete renovation in 2014. The flexibility of Optigo Networks’ solution meant the retail center’s unknown final design was not a barrier to placing IP surveillance equipment in the field.



Optigo Networks connected New York-based Boulevard Mall’s security surveillance devices in December 2015, using a Passive Daisy Chain topology.

Visual BACnet tech support team


One tech support team at a manufacturer purchased an account with Visual BACnet in April 2017, for technical problems around the world.