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» Film-Tech Forum   » Operations   » Digital Cinema Forum   » How common are NTP servers on theater networks? (Page 1)

 
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Author Topic: How common are NTP servers on theater networks?
Harold Hallikainen
Jedi Master Film Handler

Posts: 762
From: Denver, CO, USA
Registered: Aug 2009


 - posted 03-16-2013 06:25 PM      Profile for Harold Hallikainen   Author's Homepage   Email Harold Hallikainen   Send New Private Message       Edit/Delete Post 
Several USL products (such as the JSD-60 and the JSD-100) have real time clocks that are used in logging. These products also have NTP clients so the RTC can be set automatically. How common are NTP servers on theater networks?

In reviewing some manuals, I find:

1. Dolby DSS-200 mentions an NTP server in the DSS-200 when it is used as a TMS (it says to point the NTP client of other DSS-200s to this DSS-200). Is the NTP server always available on a DSS-200?

2. A text search in my GDC SX-2001A manual makes no mention of NTP.

3. A search of my Doremi DCP-2000 manuals makes no mention of NTP.

So, do you have an NTP server on your theater network?

THANKS!

Harold

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Carsten Kurz
Film God

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From: Cologne, NRW, Germany
Registered: Aug 2009


 - posted 03-16-2013 06:50 PM      Profile for Carsten Kurz   Email Carsten Kurz   Send New Private Message       Edit/Delete Post 
What do you mean with 'on your network'? Most screens I know of have their servers set to use any general use external NTP server, which makes sure that no larger deviations between the clocks (system/media block) accumulate. Doremi has that option, too. I guess any server has NTP options, even if not documented.

If access to external networks is not allowed or possible for security reasons, an internal NTP server would either need it's own radio oder GPS clock source, or be slaved to an external NTP server. But the latter would also mean a more or less controlled/firewalled access to external networks. So basically I don't see a large difference between using external NTP servers or internal NTP servers. Both need to be set up properly through network devices to accomplish security constraints.

Of course, it's one thing to have all servers on a multiplex synchronized to each other just internally, so that e.g. show starts and housekeeping is running on the same clock, and another thing to have it synced to an absolute external time reference. In some cases, the internal-only option may be sufficient.

- Carsten

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Harold Hallikainen
Jedi Master Film Handler

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From: Denver, CO, USA
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 - posted 03-16-2013 07:12 PM      Profile for Harold Hallikainen   Author's Homepage   Email Harold Hallikainen   Send New Private Message       Edit/Delete Post 
Thanks! Since I'm not in theaters, I count on this group to help me with understanding what's out there. It SEEMS that since media blocks are required to have an accurate clock to determine whether playback is allowed by the KDM, that servers would make that time information available via NTP. I also thought there would be mention of NTP servers in manuals, but there appears to be little mention.

So, I guess I can rephrase the question. Generally, do devices on your theater network have access to an NTP server (either on the local network or in the outside world)?

THANKS for all the help. I learn a lot by reading these posts.

Harold

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Dave Macaulay
Film God

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From: Toronto, Canada
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 - posted 03-16-2013 07:22 PM      Profile for Dave Macaulay   Email Dave Macaulay   Send New Private Message       Edit/Delete Post 
Theatres with a TNS/LMS have a firewalled internet connection (required for the NOC to access the system) and the TMS/LMS accesses the NOC NTP server. The devices on the theatre network can access the NOC NTP server but usually (to reduce the load on that server) the LMS/TMS runs its own NTP server and the screen servers etc access it. For the Doremi TMS systems I've installed we set the screen server NTP address to the TMS management address. On the Cinedigm LMS I believe it is the same. I have to find out what the procedure is for the Christie LMS for next week but it's probably the same.
For a theatre without a TMS/LMS, you would presumably connect to the general internet through a firewall router allowing NTP traffic and use a public NTP server.
This synchronizes the server clocks automatically: you can periodically adjust each server's clock and get close, but usually with NTP the clock's speed is adjusted to correct drift... I don't think you can make that adjustment manually.

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Steve Guttag
We forgot the crackers Gromit!!!

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From: Annapolis, MD
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 - posted 03-16-2013 11:05 PM      Profile for Steve Guttag   Email Steve Guttag   Send New Private Message       Edit/Delete Post 
We have found that without an NTP clock, time will drift so we ensure that there is an NTP server locally in each theatre. This will be a TMS that references an external NTP or in smaller plexes (including singles) a PC that will function as an NTP.

It is true that Dolby servers CAN function as an NTP BUT the server acting as an NTP server for other things must have a good NTP source it can reference from.

In a proper Dolby network, it is set up as a spoke-and-wheel. At the center is the TMS/LMS (typically a DSL100 or DSL200). The DSL should have access to an external NTP source (like a NOC's NTP clock or even one like "NIST"). Each server within the complex then references its clock from the DSL. At that point, each individual server will broadcast NTP time for other clients to read the time.

Note, in the Dolby scheme each auditorium is an island and the DSS server acts as the bridge between the individual auditoriums and the theatre as a whole. Thus, any device within the specific auditorium can only "see" as far as its DSS server. The DSS server has to provide the NTP time at that point.

Dolby creates many small networks in this system...which should provide a very robust system since each network is relatively small and has much less traffic than a typical large or flat network.

To use NTP as an example...lets say you have a 10-plex. The DSL gets the time from an external source. Only one device is pinging the external NTP...which keeps traffic down going to the Internet and also keeps the external NTP from seeing a site being over zealous in consuming resources asking for time (also known a "flooding"). The DSL in this situation only has 10 things asking for the time of it...again, not too much traffic. And at each auditorium only a handful of things (at most) would be asking for the time (projector, sound processor, automation and maybe a couple other devices, in a fancy system). In each network, traffic is kept small and reliable. It also means that within an auditorium, if they all reference off of the server's clock, all devices have the same relative time...which for troubleshooting, can be a huge help.

I have found that without an NTP...none of the servers will keep accurate enough time and there will be drift. All DCinema server manufacturers have a means of NTP synchronization but I don't believe all can act as an NTP server. I don't think any of the other DCinema server companies came up with the type of network like Dolby...where it was incumbent on the cinema server to also handle NTP as well as have an internal router.

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Harold Hallikainen
Jedi Master Film Handler

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From: Denver, CO, USA
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 - posted 03-17-2013 12:32 AM      Profile for Harold Hallikainen   Author's Homepage   Email Harold Hallikainen   Send New Private Message       Edit/Delete Post 
Thanks for the detailed responses!

Harold

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Pete Naples
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 - posted 03-18-2013 06:12 PM      Profile for Pete Naples   Email Pete Naples   Send New Private Message       Edit/Delete Post 
Note that with Dolby servers, if the external NTP reference has more than a certain number of hops (I think I remember the number being 12) the software decides the reference isn't accurate enough and will ignore it. You can check in Show Manager, if the configured NTP is not shown as connected, then it's not using the external reference.

Some broadband router/modems have NTP functionality, as do some NAS units. You could also run a small app on a PC on the local network, many sites have such a PC for admin purposes.

We have our own simple low cost NTP server which we use when an internet reference that the Dolby servers like cannot be found.

Doremis don't seem to care, there's a text file you can edit which points it to NTP.

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Steve Guttag
We forgot the crackers Gromit!!!

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 - posted 03-18-2013 08:46 PM      Profile for Steve Guttag   Email Steve Guttag   Send New Private Message       Edit/Delete Post 
I believe the limit is 15 hops and, as I understand it, that is in the NTP protocol, not something that Dolby arbitrarily made up.

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Danial Simmonds
Expert Film Handler

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From: Kota Damansara, Selangor, Malaysia
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 - posted 08-20-2013 08:26 AM      Profile for Danial Simmonds   Author's Homepage   Email Danial Simmonds   Send New Private Message       Edit/Delete Post 
What we do over here is have the TMS update the time from a NTP server by giving it access through the firewall. All other theater servers and devices that has NTP updates the time from the TMS.

Doremi does have ntp you can find the script using the terminal.

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Marco Giustini
Film God

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 - posted 08-20-2013 12:25 PM      Profile for Marco Giustini   Email Marco Giustini   Send New Private Message       Edit/Delete Post 
I understand that with version 2.4.2 you can set it on the control panel.

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Pete Naples
Phenomenal Film Handler

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 - posted 08-20-2013 01:33 PM      Profile for Pete Naples   Email Pete Naples   Send New Private Message       Edit/Delete Post 
That was my understanding too Steve. However it seems to be with Doremis looking at NTP pools they aren't fussed. Perhaps it's applicable when there's a single reference, rather than a pool?

As I touched on above, our workaround is to have our low cost NTP server on the network, or to utilise a VPN router device that also has NTP functionality.

Back in the day, the projecitonist phoned the speaking clock and checked his watch [Roll Eyes]

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Dennis Benjamin
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 - posted 08-20-2013 02:19 PM      Profile for Dennis Benjamin   Author's Homepage   Email Dennis Benjamin   Send New Private Message       Edit/Delete Post 
The theatres I have set up have their servers call out to an NTP Time server on the Local Area Network. That NTP Time server is the LMS/TMS computer (Windows Time Server). In turn, that computer (TMS/LMS) calls out to NIST on the Internet to get the time. I haven't had any issues, other than when I have updated software and had to go in and reset the NTP info on the individual Digital Cinema Servers themselves.

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Chris Slycord
Film God

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From: 퍼항시, 경상푹도, South Korea
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 - posted 08-20-2013 04:40 PM      Profile for Chris Slycord   Email Chris Slycord   Send New Private Message       Edit/Delete Post 
quote: Pete Naples
Back in the day, the projecitonist phoned the speaking clock and checked his watch
I worked with a guy who only checked his watch for the first auditorium and set them all to that time. Too bad that by the time he'd threaded all 8 screens, he was off by over 10 minutes for that final one.

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Jim Cassedy
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 - posted 08-20-2013 05:15 PM      Profile for Jim Cassedy   Email Jim Cassedy   Send New Private Message       Edit/Delete Post 
How ironic this topic should come up today.

Earlier this afternoon, I was doing some work at a theater
and I noticed the system clock on their digitalserverthingy
was 10min fast.

Rather than fix the clock, they simply schedule everything 10min early.
(So a 4pm show is programmed to start at 3:50)

I offered to fix it for them, but I was told "it would only confuse the staff".

Ooooooohhhhhhh Kaaaaaayyyyyyyy . . . . . . . . . .

ACTUAL PICTURE!
 -

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Frank Cox
Phenomenal Film Handler

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From: Melville Saskatchewan Canada
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 - posted 08-20-2013 05:22 PM      Profile for Frank Cox   Author's Homepage   Email Frank Cox   Send New Private Message       Edit/Delete Post 
I never knew that you could set the clocks on digital cinema stuff. Isn't that a security hole? If I have a key for last week's movie and set the clock back to last week, I can play it again using last week's key.

The clocks on my digital cinema stuff (GDC server and Christie projector) are nowhere near synchronized either with each other or the actual time. Without actually checking to be sure, I think one is ten minutes or so slow, and the other is several minutes fast. It doesn't appear to affect anything and since I don't use the automatic scheduled start stuff I really don't pay much attention to what those clocks say.

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