4 Apr
2016
4 Apr
'16
10:06 a.m.
On Sun, Apr 03, 2016 at 10:05:07PM +0200, Harald Welte wrote:
On Sun, Apr 03, 2016 at 12:00:03AM +0200, Neels
Hofmeyr wrote:
Ok, good thing I asked, then. So far I assumed that each hNodeB contains
an RNC with its own RNC Id, and any number of RNC Ids are sent via the
same HNB-GW to the CN.
So when the CN pages on Iu, "RNC Id wise" we'd always page on all of the
other hNodeBs on the same HNB-GW. It's up to the HNB-GW to remember which
IMSIs were last seen on which hNodeB and page only there first.
We've recently noticed that our HNB-GW
doesn't ever send an id-Reset to
the CN. Now I'm trying to pinpoint precisely when this should happen.
For discussion, I'm focusing on CS, though this applies to PS as well.
It should happen once every time the signalling link between the HNB-GW
and the respective CN node is established, or whenever the HNB-GW looses
some state and thus wants to request re-initialization of the state on
the CN side. * A hNodeB sends a HNB-REGISTER-REQUEST to the HNB-GW
* The HNB-REGSITER-RESPONSE contains the RNC-ID, i.e. the HNB-GW
tells the hNodeB which RNC-ID to use. Each logical HNB-GW has one
RNC-ID and thus all hNodeB connected to it should have the same
Interesting, because so far I've actually configured the RNC-Id in the
hNodeB's config interface (see our wiki page for "UMTS Configuration",
which lists the parameter).
I wasn't aware yet, but in the pcaps, there is indeed an RNC Id sent from
the HNB-GW during the HNB_REGISTER_ACCEPT (e.g. 14). But subsequently the
hNodeB sends a different RNC Id (the one configured in the hNodeB
settings, e.g. 0). So our hNodeB apparently doesn't remember the RNC Id it
receives during the HNB_REGISTER_ACCEPT.
What would you say, is this just yet another thing that the operator has
to configure correctly? Is it a spec violation by our particular hNodeB?
Or should the HNB-GW actually overwrite the RNC-Id going to the CN?
Maybe our HNB-GW sends the HNB_REGISTER_ACCEPT incorrectly and the hNodeB
refuses to take on the RNC Id? But in that case, I'm pretty sure, it
wouldn't accept UE subscribers, as seen when no CN is connected.
For the time being I'll just configure the hNodeB and the HNB-GW to use
the same RNC Id.
~Neels