in reply to Re^4: UDP server with IO::Socket::INET
in thread UDP server with IO::Socket::INET

If this was my project, I would definitely use an explicit disconnection.

That said, ICMP does provide "Destination Unreachable" which could be used to detect clients that are MIA. Of course, using ICMP for this would be a lot of work for very little practical gain, which is why I recommended multicast.

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Re^6: UDP server with IO::Socket::INET
by ikegami (Patriarch) on Mar 04, 2010 at 19:37 UTC

    which is why I recommended multicast.

    Are you saying that multicast drops unreachable machines automatically?

[reply]

      No, I'm saying that it is possible to detect missing clients with ICMP but a much better alternative would be an existing explicit connection protocol, such as multicast.

      Update: I realized too late that multicast doesn't actually use explicit connections but that's part of the beauty of multicast.

[reply]

        Ok, so your suggestion that multicast is an alternative to ICMP is wrong. You need some kind of connection and disconnection mechanism whether or not multicasting is used.

        Note that I don't think ICMP would even work as a disconnection mechanism. It will only tell you whether the machine is reachable (and might not even do that with firewalls), not if a UDP port is reachable.

        but that's part of the beauty of multicast.

        It's part of the beauty of UDP, as it is what allows multicast to exist.

[reply]

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