SGSN bug report

[Pierre Kim]

Hello,



While testing with multiple devices I found a problem where Samsung phones
don't correctly respond to identity request messages.

Attached is the pcap file of the GPRS-NS transmission.



Regards,

Pierre

[Holger Hans Peter Freyther]

Post by Pierre Kim
Hello,

Hi,

Post by Pierre Kim
While testing with multiple devices I found a problem where Samsung phones
don't correctly respond to identity request messages.
Attached is the pcap file of the GPRS-NS transmission.

have you seen the LLC-DISCARDED message? This indicates that a PCU failed
to transmit the data to the phone. Which PCU are you using?

holger

[Pierre Kim]

Hello,

I am using a nanoBTS EDGE model.

An iPhone on the same BTS doesn't have this issue.
But Samsung phones and HTC Diamond do.

Everything else(voice/sms) works flawlessly.

Regards,
Pierre

-----Original Message-----
From: openbsc-***@lists.osmocom.org
[mailto:openbsc-***@lists.osmocom.org] On Behalf Of Holger Hans Peter
Freyther
Sent: Saturday, October 25, 2014 6:04 PM
To: Pierre Kim
Cc: ***@lists.osmocom.org
Subject: Re: SGSN bug report

Post by Pierre Kim
Hello,

Hi,

Post by Pierre Kim
While testing with multiple devices I found a problem where Samsung
phones don't correctly respond to identity request messages.
Attached is the pcap file of the GPRS-NS transmission.

have you seen the LLC-DISCARDED message? This indicates that a PCU failed to
transmit the data to the phone. Which PCU are you using?

holger

[Holger Hans Peter Freyther]

Post by Pierre Kim
Hello,

Hi,

Post by Pierre Kim
I am using a nanoBTS EDGE model.

that is what I assumed. You will need to figure out what the
ip.access PCU is doing.

Post by Pierre Kim
An iPhone on the same BTS doesn't have this issue.
But Samsung phones and HTC Diamond do.

Different stacks, different firmware, it doesn't say much. But
please have a look at the trace:

Packet Delta-TS Direction TLLI message
#7 0 MS->SGSN 2584537203 GMM Attach Request
#8 ~0s SGSN->MS 2584537203 GMM Identity Request
#10 ~2s PCU->SGSN - LLC Discarded

In packet #10 the PCU tells the SGSN that 9 octets could not be
transferred. Assuming you included the full trace the '9' are the
nine bytes of the "LLC/GMM Identity Request".

This means that the closed source PCU of the nanoBTS EDGE model
couldn't transfer the LLC data to the MS within the 2s deadline
that was set in the PDU-Lifetime of packet #8. Now nobody in this
community can tell you why the PCU of the nanoBTS doesn't transfer
it. Last time I tried to contact an engineer at ip.access (the one
that patched GSMTAP for PDCH handling), I was ignored.

kind regards
holger