The MAC layer is the building block that is used to build repeater capability. To implement Repeater mode, we use a network layer header that comes after the MAC layer header in each packet. In this network layer there is additional packet tracking to eliminate duplicate broadcasts.
In this delivery method, the device sends both unicast and broadcast packets out as broadcasts that are always repeated. All repeated packets are sent to every device. The devices that receive the broadcast send broadcast data out their serial port.
When a device sends a unicast, it specifies a destination address in the network header. Then, only the device that has the matching destination address sends the unicast out its serial port. This is called a directed broadcast.
Any node that has a CE parameter set to router rebroadcasts the packet if its BH (broadcast hops) or broadcast radius values are not depleted. If a node has already seen a repeated broadcast, it ignores the broadcast.
The NH parameter sets the maximum number of hops that a broadcast transmission is repeated. The device always uses the NH value unless you specify a BH value that is smaller.
By default the CE parameter is set to route all broadcasts. As such, all nodes that receive a repeated packet will repeat it. If you change the CE parameter, you can limit which nodes repeat packets, which helps dense networks from becoming overly congested while packets are being repeated.
Transmission timeout calculations for Repeater/directed broadcast mode are the same as for DigiMesh broadcast transmissions.