PCU socket not connected, dropping message

Pau Espin Pedrol pespin at sysmocom.de
Mon Nov 23 20:45:10 UTC 2020


Indeed PCU is in charge of handling PDCH timeslots which are related to

"pcu_bts" is not a regular file, is a unix domain socket which is used
to interconnect osmo-bts-trx and osmo-pcu. So having failures there
means you either have a configuration problem (path incorrect
configured) or a permission/ownership problem, maybe because you run
osmo-bts-trx or osmo-pcu with root and the other with regular user, so
the unix domain socket is created with permissions which the other
process cannot then use.

So, assuming you don't have issues BTS<->PCU issues and everything's
fine, seeing "PCU socket not connected, dropping message" could mean PCU
crashed at that time and is no longer available. When you start a phone
call there may be PCU related traffic because the MS was probably doing
data transfers in PDCH timeslots until the exact moment when you page
the MS and ask it to go for a call, so the MS needs to "suspend" the
GPRS use and notifies the network.

- Pau Espin Pedrol <pespin at sysmocom.de>         http://www.sysmocom.de/
* sysmocom - systems for mobile communications GmbH
* Alt-Moabit 93
* 10559 Berlin, Germany
* Sitz / Registered office: Berlin, HRB 134158 B
* Geschaeftsfuehrer / Managing Director: Harald Welte

More information about the baseband-devel mailing list