If CCM is using 6509 switch as external NTP source and 6509 has the following command for the DST:
clock timezone EST -5
clock summer-time EDT recurring 2 Sun March 2:00 1 Sun Nov 2:00.
and the CCM didn't apply patch in spring,
I think CCM should get clock automatically adjusted based on the NTP from 6509, right?
NTP provide the Greenwich time for device, all ntp client need offset setting by it's own.
In you case, the 6509 will get DST time change by itself because of the clock summer-time command. It's not because of it's a NTP SERVER.
After all, NTP Servers/Clients has nothing to do with the DST change.
Hope this helps.
Just to confirm my understanding. So if I understand properly, even on Nov 4 2:00 am, 6509 falls back to standard DST time. CCM still receive the greenwich time from 6509 and have to offset it to standard DST by its own. It will never receive the 6509's local time as a clock. So that means in any case I need DST mechnism on local device. Right?
This doc lists the various Patches and or Manual workarounds for the different CCM Versions and releases;
Field Notice: FN - 62669 - U.S. Daylight Saving Time Policy Changes for Cisco CallManager/Communications Manager
Hope this helps!