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TTCN timers controlled via a virtual clock [message #1861642]

Wed, 25 October 2023 07:20

Olaf Bergengruen

Messages: 127
Registered: November 2018

Senior Member

Hello Titan experts,

is there a way to control the TTCN timers via an external or virtual clock (not the host clock) ?

This could be useful if we are testing fast protocols against a DUT (device under test) running on a different host connected to our Tester via the Internet. Of course, the DUT needs to by synchronized by the same virtual clock.

index.php/fa/43631/0/

Thanks for any comments.
Olaf

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Re: TTCN timers controlled via a virtual clock [message #1861646 is a reply to message #1861642]

Wed, 25 October 2023 09:19

Harald Welte

Messages: 148
Registered: July 2017
Location: Berlin, Germany

Senior Member

Given that we're talking about TTCN-3 and high-level software/protocol testing far from hard real time constraints: When speaking about "clock" I guess you're more referring to something like a RTC here, rather than a clock in the electrical engineering sence (like a PDH/SDH network clock, or the clock signal used to generate the stable carrier frequency and bit-clock in wireless base stations)?

If that's true, you could probably simply have your "virtual clock" as a NTP server and synchronize the host running system adapter + ATS just as well as the DUT?

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Re: TTCN timers controlled via a virtual clock [message #1861650 is a reply to message #1861646]

Wed, 25 October 2023 11:41

Olaf Bergengruen

Messages: 127
Registered: November 2018

Senior Member

No, Harald, I would like to implement a virtual clock (independent of the host clocks) controlling all other clocks.

Long ago we implemented such a system but not with TTCN. The idea was simple: When all jobs are done in all sub-systems the global timer-tick is incremented by one.

The result was that test cases that required lots of configurations and heavy L2 signalling run much slower than in real time also depending on the host CPUs. But test cases where most of the time was nothing to do like location update test cases waiting 60 minutes for next update, these test cases run much faster than real time.

Regard,
Olaf

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Re: TTCN timers controlled via a virtual clock [message #1861651 is a reply to message #1861650]

Wed, 25 October 2023 11:59

Gábor Szalai

Messages: 134
Registered: December 2015

Senior Member

Currently it is not possible, without changing the internal logic of the timer handling.

Maybe it can be simulated via a specific test port.
So instead of waiting for a timeout, the test code waits for a message on the test port.

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Re: TTCN timers controlled via a virtual clock [message #1861652 is a reply to message #1861651]

Wed, 25 October 2023 12:24

Olaf Bergengruen

Messages: 127
Registered: November 2018

Senior Member

That sounds like a good idea, Gábor.
The con is that I would need to change official test suites in non trivial ways.

Do you think it would be worth investigating to build a special version of the Titan compiler where the basic timer operations are changed to not use the host clock but rather a global integer in a shared memory area counting timer-ticks ?

Regards,
Olaf

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