[ntp:questions] multicast/broadcast to multi subnet

Danny Mayer mayer at ntp.isc.org
Tue Feb 28 17:35:55 UTC 2006

dengfeng at gmail.com wrote:
> We have about 20 subnet and want to use one server as a
> multicast/broadcast server for all the subnet, if it's within
> subnet(, it works fine. If I set the server to broadcast to
> a.b.255.255, it did not go through.
> Any suggestions?

You need to set the multicast hop count as the default is 0 so the
packets never leave the subnet. The number of hops you need to specify
is dependent on your network configuration. use traceroot to find out
how many hops you need from the furthest system. This is the TTL option
which despite its name is really a hop count. The documentation on this
appears to be wrong. It says that the ttl default is 127, but the code
looks like it's actually 0.


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