Configuring macOS Server for Multicast Streams

If you are sending or receiving multicast streams from a macOS server, multicast fails if the receiving or sending interface is not the macOS default interface. If no default gateway is defined on a macOS server, the default interface is en0. To use a different interface than the default, change the default interface for your server

Run the following commands:

# route delete default new_interface_ip
# route add default new_interface_ip

Example

Server Name	en0 IP Address	en5 IP Address
a4_1	10.211.1.61	10.215.1.61
a4_2	10.212.1.62	10.216.1.62

In this example, server a4_1 acts as the multicast receiver and sends the stream over UDP to server a4_2. Server a4_2 then broadcasts the multicast streams to waiting receivers. Since both servers are using a non-default interface (not en0) to receive and send the multicast streams, we must set the interface receiving and sending the multicast streams as the server default interface.

Run the following command on a4_1:

# route delete default 10.215.0.1
# route add default 10.215.0.1

Run the following command on a4_2:

# route delete default 10.216.0.1 
# route add default 10.216.0.1

Note: The interface IP addresses 10.215.0.1 and 10.216.0.1 routes are the primary gateways and route all 10.215.0.* and 10.216.0.* traffic, respectively.