You are looking for UPnP ("Universal Plug 'n' Play"), which involves an exchange of UDP multicast SOAP messages. It is specifically designed for this task ... being able to ask the local network for available servers and any information they care to send. As an example, ReplayTV uses this protocol to autodetect other players on your LAN, so that you can stream within your house.

Though I didn't see it on CPAN, a quick google yielded PerlUPnP at sourceforge.

use UPnP::ControlPoint;

  my $cp = UPnP::ControlPoint->new;
  my $search = $cp->searchByType("urn:schemas-upnp-org:device:TestDevi
+ce:1", 
                                 \&callback);
  $cp->handle;

  sub callback {
      .
      .
      .
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