[ntp:questions] Multicast question

Danny Mayer mayer at ntp.isc.org
Mon Mar 3 03:34:14 UTC 2008

Jan Ceuleers wrote:
> Martin Burnicki wrote:
>> I'd expect that either the kernel routed multicast packets to all interfaces
>> (isn't that what routers do with multicasts, contrarily to broadcasts?), or
>> the application would send an individual packet on each interface.
> Routers have to be told (by means of multicast protocols such as IGMP) 
> which interfaces to replicate multicast packets onto.

That assumes that there's a router involved. If it's just to the local 
LAN then you may not have a router able to route to the other 
interfaces. In this case it almost certainly have to be done on the 
local server sending the packets.


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