[ntp:questions] Multicast question

Danny Mayer mayer at ntp.isc.org
Fri Feb 29 12:53:37 UTC 2008

Martin Burnicki wrote:
> Danny Mayer wrote:
>> John Vossler wrote:
> [...]
>>> My initial reaction to this issue was to determine if there was an OS
>>> (Solaris) directive to include the multicast for other interfaces in the
>>> group as reported by "netstat -g".  Or a method to specify the multicast
>>> interfaces in the ntp.conf file (apparently not, or not easily).
>> No, and certainly it has not been implemented in NTP.
> If ntpd has been configured to send multicasts, shouldn't it by default send
> multicasts on every interface it actually uses?
> I had expected ntpd would already do so.

How could you do that? You have one packet that you are sending out. It 
can only go out on exactly one interface. You can only choose which 
interface to use, you cannot select more than one.

> Does someone know how this is handled by other protocols using multicast,
> e.g. SLP or mDNS?

They probably don't. Similarly DHCP.

> Martin

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