[c-nsp] NTP message sent to 224.0.1.1, from interface 'NULL' (0.0.0.0).

[Aaron]

Have you set your ntp source interface by any chance?
It has been awhile since I've been on IOS.

It shouldn't have a big impact to your ntp clients unless you have an odd
setup with your ntp configuration or architechture.
I have my core set up to peer with each other directly (slaved off of a
couple of master NTP servers that are gps or stratum 1) and have my edge
devices by clients of the local core. That may not help in your setup. All
devices are set to use UTC so that timestamps are all the same. You can use
a local one but you should have them all in the same timezone to help
corordinate events in syslogs etc.


On Tue, Jul 2, 2013 at 9:30 AM, Victor Sudakov <vas at mpeks.tomsk.su> wrote:

> This must be some NTP v4 novelty?
>
> All right, how do I revert to the old behaviour, or at least limit the
> ttl of those multicast packets sent from the 'NULL' interface?
>
> "ntp multicast ttl 1" on the interface does not seem to have any
> effect. Configuring a broadcast destination on an interface does not
> help either.
>
> I have tried configuring "ntp broadcast version 3" on the interface,
> but still see the dreaded packets to 224.0.1.1 with a big ttl.
>
> Those multicast packets with the big ttl are forwarded all over the
> network and cause confusion among ntp broadcast clients.
>
>
> Phil Bedard wrote:
> > NTP "broadcast" sends the messages using multicast, to 224.0.1.1.  See
> > RFC5905.
> >
> > Phil
> >
> > On 7/2/13 6:09 AM, "Victor Sudakov" <vas at mpeks.tomsk.su> wrote:
> >
> > >Colleagues,
> > >
> > >Why is a CISCO3945 router sending multicast NTP packets with ttl=31 (!)
> > >while I have never configured it to do so? "debug ntp packets" reveals:
> > >
> > >NTP message sent to 224.0.1.1, from interface 'NULL' (0.0.0.0).
> > >NTP: ntpio_send_ipv4 called with bcast address and NULL interface
> > >
> > >In fact, it is configured to send NTP broadcast messages on some
> > >Ethernet interfaces, but not multicast. What could be wrong?
> > >
> > >!
> > >interface GigabitEthernet0/0
> > > description Orlovka
> > > ip address 10.14.128.225 255.255.255.224
> > > ip pim sparse-dense-mode
> > > duplex auto
> > > speed auto
> > > ntp broadcast destination 10.14.128.255
> > > ntp broadcast
> > >end
> > >
> > >
> > >--
> > >Victor Sudakov,  VAS4-RIPE, VAS47-RIPN
> > >sip:sudakov at sibptus.tomsk.ru
> > >_______________________________________________
> > >cisco-nsp mailing list  cisco-nsp at puck.nether.net
> > >https://puck.nether.net/mailman/listinfo/cisco-nsp
> > >archive at http://puck.nether.net/pipermail/cisco-nsp/
> >
>
> --
> Victor Sudakov,  VAS4-RIPE, VAS47-RIPN
> sip:sudakov at sibptus.tomsk.ru
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