| 摘要 |
A global broadcast communication network system having a plurality of subnets. The system may incorporate a building and automation control network (BACnet) protocol. Each subnet may have a one active BACnet broadcast management device (BBMD) for broadcasting messages to other subnets. Also, there may be BIP (BACnet over IP) devices, such as controllers, tools and stations, in the subnets. One of the BIP devices in each subnet may be configured or enabled as a passive BBMD. If there is a failure of the active BBMD in a subnet, then the passive BBMD of the same subnet may detect the failure and assume the role of the active BBMD to minimize or eliminate possible disruption of communication across the subnets. Each BBMD may have and maintain a broadcast distribution table (BDT) which contains information about BBMDs in other subnets. Each BBMD may provide updated BDT information to the other BBMDs. |
