[ntp:questions] Multicast and dynamic interfaces

barry bouwsma free_beer_for_all at yahoo.com
Wed Jul 9 19:30:40 UTC 2008


Moin,

ntp-dev-4.2.5p118, Linux latest-ish.  Also observed with ntp-dev-4.2.5p113


Should ntpd be able to listen for multicasts on interfaces that
get added/configured after ntpd starts?

For example, I just brought up and configured this interface:
Jul  9 21:12:46 localhost ntpd[3422]: Listening on interface #8 eth3, fe80::200:e8ff:fe00:fe0#123 Enabled
Jul  9 21:12:46 localhost ntpd[3422]: Listening on interface #9 eth3, 172.27.72.99#123 Enabled

However I'm not able to get it to hear the multicast data which
can be heard, no matter how long I wait, unless I restart ntpd,
like so:

Jul  9 21:15:42 localhost ntpd[19791]: Listening on interface #3 eth3, fe80::200:e8ff:fe00:fe0#123 Enabled
Jul  9 21:15:42 localhost ntpd[19791]: Listening on interface #4 lo, 127.0.0.1#123 Enabled
Jul  9 21:15:42 localhost ntpd[19791]: Listening on interface #5 eth3, 172.27.72.99#123 Enabled
Jul  9 21:15:43 localhost ntpd[19791]: Listening on interface #6 multicast, 224.0.1.1#123 Enabled
Jul  9 21:15:43 localhost ntpd[19791]: setsockopt IP_ADD_MEMBERSHIP failure: No Jul  9 21:15:43 localhost ntpd[19791]: Failed to add Multicast Listener 224.0.1.1
(no big deal that)
Jul  9 21:15:43 localhost ntpd[19791]: Listening on interface #7 multicast, ff05::101#123 Enabled
Jul  9 21:15:43 localhost ntpd[19791]: Added Multicast Listener ff05::101 on interface #7 multicast


And voila, now I can hear and use that multicast data...
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
 fe80::200:c0ff: .DCFa.           1 m   14   16  200    0.741    1.240   0.008


Is this a case of missing or non-functioning code, or is this
something that really isn't possible?


thanks,
barry bouwsma


      




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