2013/3/11 drbrain (Eric Hodel) <drbrain / segment7.net>:

> Feature #8075: Add socket interface class to list interfaces
> https://bugs.ruby-lang.org/issues/8075

> For IPv6 multicast an interface may be set to indicate which interface IPv6 packets should be sent on.
>
> The attached patch allows interfaces to be looked up by name (or index) for use in setting this socket option.

I think this is a good feature to support RFC 3493
(Basic Socket Interface Extensions for IPv6).

Note that I didn't design/implement this feature just because
I have no experience with multicast.
-- 
Tanaka Akira