To send announces with VLC, you need to use the complex syntax of VLC's stream output, like this:
%vlc -vvv input_stream --sout '#standard{access=udp,url=239.255.12.42,sap="Test Stream"}' --ttl 12
where video1.xyz is the file you want
to stream, 239.255.12.42 is the multicast IP
address you want to stream on, Test Stream is
the name that will be used for this program in the SAP announces and
12 is the value of the TTL (Time To Live) of the
stream and of the SAP announces.
To do the SAP announces in IPv6, just add the sap_ipv=6 option:
%vlc -vvv input_stream --sout '#standard{access=udp,url=239.255.12.42,sap="Test Stream",sap_ipv=6}' --ttl 12