[erlang-questions] clarify: SO_REUSEADDR under darwin?

Per Hedeland <>
Sat Nov 10 00:57:14 CET 2007


"Valentin Micic" <> wrote:
>
>Not that it matters much but... a specific interface is important 
>considering what happens on a link-level.

Certainly, but the interface's unicast address(es) aren't. And I don't
think binding the socket to a particular unicast address will select the
corresponding interface for multicast on a host that has multiple
interfaces - that's one of the things add_membership is for.

>I have experimented with this quite a long time ago, when Ethernet segment 
>just exactly that... I would be interested to know how does L-3 switch 
>handle multicasts these days? Is there any special configuration required by 
>a switch?

I think "it varies". See e.g.
http://www.cisco.com/univercd/cc/td/doc/cisintwk/ito_doc/ipmulti.htm#wp1020671
and make a guess at what a low-end switch without a high-end one to back
it up does (my guess is that it does "the default", i.e. treats
multicast as broadcast).

--Per



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