Bug #4856

PCU is running but has no NS connection and does not retry.

Added by keith 4 months ago. Updated 3 months ago.

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It has been noticed that at times osmo-bts, osmo-pcu are up and running on a sysmobts, GPRS is configured but there is no NS connection to the SGSN.

What I don't have about this:

  • A method to reproduce.
  • logs leading up to failure.
  • I don't know if the NS was up and failed, or if it never came up on pcu startup.
  • osmo-bts and pcu are not current master, if fact there are some various versions installed.. (BSC is nitb)

As I am writing this, I have one case of running osmo-pcu with no connection.

pcu is not logging ANYTHING. (logging level set-all debug)
version: OsmoPCU
show stats: all counters are zero.

ntib shows all of the "states" Oper 'Enabled', Admin 'Unlocked', Avail 'OK'
as does the associated pcu osmo-bts

also, shows PCU connected:

OpenBSC# show bts 2
BTS 2 is of sysmobts type in band GSM850, has CI 2 LAC 269, BSIC 63 (NCC=7, BCC=7) and 1 TRX
Description: (null)
PCU version connected

To possibly simplify a little:
It seems to be that the PCU is in a states where it "knows" that the NS is down

OsmoPCU# show ns
Encapsulation NS-UDP-IP     Local IP:, UDP Port: 0

yet it it not trying to bring it up.
Maybe the bts did not inform the PCU of the config?

show bts statistics: also all counters at ZERO.
all rate-counters are zero.

really looks like it was never initialised.

Maybe needless to say, but worth adding - systemctl restart osmo-pcu restores service.


#1 Updated by keith 4 months ago

  • Description updated (diff)

#2 Updated by lynxis 3 months ago

OsmoPCU# show ns
Encapsulation NS-UDP-IP     Local IP:, UDP Port: 0

This looks like there wasn't any NS configuration transmitted over the PCU socket. Can you update to the latest PCU?

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