Multicast Loopback

Onload User Guide (UG1586)

Document ID
Release Date
1.2 English

The socket option IP_MULTICAST_LOOP controls whether multicast traffic sent on a socket can be received locally on the machine. Receiving multicast traffic locally requires both the sender and receiver to be using the same Onload stack. Therefore, when a receiver is in the same application as the sender it will receive multicast traffic. If sender and receiver are in different applications then both must be running Onload and must be configured to share the same Onload stack.

For two processes to share an Onload stack both must set the same value for the EF_NAME parameter (max eight chars). If one local process is to receive the data sent by a sending local process, EF_MCAST_SEND must be set to 1 or 3 on the thread creator of the stack.

User of earlier Onload versions and users of EF_MULTICAST_LOOP_OFF should refer to the Parameter Reference table Parameter Reference for details of deprecated features.