Using trxcon/fake_trx with PDCH for TTCN3 tests

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Oliver Smith osmith at sysmocom.de
Tue Jul 30 08:23:45 UTC 2019


Hello Harald and Vadim,

On 7/29/19 8:42 PM, Harald Welte wrote:
> Thanks also from my side.  Given that the amount of resources we have
> for writing PCU tests is rather limited, I would suggest Oliver to stay
> with virt_phy for now and focus on the actual PCU tests and not on
> building required infrastructure.

Sounds good.

>> But as I'm just diving into this, I'll get the existing but disabled
>> (probably incomplete?) TC_ul_tbf and TC_ul_tbf_single_llc_sizes tests
>> running first. I'll start with virt_phy for now, and then see how far I
>> can get with it.
> 
> The tests you mentioned were passing at some point.  Of course our
> TTCN-3 infrastructure and OsmoBTS as well as OsmoPCU have evolved since,
> so there may be some fall-out :(

It is great that they were already passing in the past. Harald, do you
happen to still have the configs around for running these two tests?

I am trying to piece it together, and so far I have the following. It
would be great if you could point out any misconceptions I have.

The raw PCU tests, that are currently running in Jenkins, only start
OsmoPCU and the testsuite. When doing the same for TC_ul_tbf and
TC_ul_tbf_single_llc_sizes, the testsuite fails to establish the BSSGP
connection:

> MTC at gsmdevel: Test case TC_ul_tbf finished. Verdict: fail reason: Timeout establishing BSSGP connection

(This is confusing me a bit, isn't the Gp connection between the SGSN
and GGSN according to [1]? But I am assuming, that this means the Gb
connection towards the PCU.)

Looking at the osmo-pcu log, I find that it won't do anything (not
accept connections) until it successfully connects to /tmp/pcu_bts.

I am starting osmo-bts-virtual in order to provide /tmp/pcu_bts. The
socket appears, but it will also not properly start up until it connects
to something via A-bis OML. So I am also starting osmo-bsc to provide
that (I have looked at ttcn3-bts-test, which does it the same way).

Now osmo-bts-virtual is connecting to osmo-bsc, but osmo-bsc is dropping
the connection immediately for some reason. Probably a mismatch in the
configs, though at least the unit id is matching.

My current understanding is, that the following components need to run:

osmo-pcu
|
| /tmp/pcu_bts
|
osmo-bts-virtual ---A-bis OML--- osmo-bsc
|
| ?
|
virt_phy
|
| /tmp/osmocom_l2
|
testsuite


Is that accurate?
How does the connection between osmo-bts-virtual and virt_phy work?

Thanks,
Oliver

-- 
- Oliver Smith <osmith at sysmocom.de>            https://www.sysmocom.de/
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