discovery

[Jim Larson]

In message <200007122028.PAA53463@REDACTED> Scott Fritchie writes:
>At the moment, we've been using multicast IP has a hack around this
>void.  If a node is rebooted or loses contact with the rest of the
>cluster, an alarm eventually goes off and the lost node sends a single
>"Anybody out there?  I am 'node@REDACTED'" multicast UDP packet.

Well, substitute "broadcast" for "multicast".  An IPv6 "anycast"
is what we'd really like here.

>The rest of the cluster is also listening for those multicast packets.
>(The multicast address is configured out-of-band.)  When one arrives,
>a regular Erlang message is sent to 'node@REDACTED', which automagically
>triggers the mechanisms used to keep track of Erlang nodes.  I'll
>volunteer Jim Larson to speak up if I've misrepresented his work or if
>y'all have further questions.  :-)

The only further thing I'd mention is that we found it useful to
add the "-connect_all false" argument to the emulator's command-line
invocation, to turn off the default behavior where each node in a
distributed system sends heartbeat messages to all other nodes.
For our application, only a single node really cares about the
status of the others.

Jim