- This option instructs the udp sender to set the time to live to
- \"num\" for the sending udp socket. Only useful for multicast
- udp streaming.
+ This option applies exclusively to multicast UDPv4/v6 streaming.
+
+ For the sending UDPv4 socket it sets the multicast Time-To-Live
+ value to \"num\". Traditional TTL scope values are: 0=host,
+ 1=network, 32=same site, 64=same region, 128=same continent,
+ 255=unrestricted. Please note however that this scoping is not
+ a good solution: RFC 2365 e.g. presents a better alternative.
+
+ When using UDPv6 multicasting, the option sets the number of
+ multicast hops (as described in RFC 3493); a value of -1
+ allows the kernel to auto-select the hop value.