Hello Harald, I'm attaching config and pcap. Hopefully mailserver allows
attachments.
Regarding SABME message it's correct behaviour, I checked twice, BSC
initializes link establishment and BTS responds with UA
Today I was digging in dahdi-linux docs again and I see that it uses BKL
mechanisms in the kernel. Is it still valid? Because BKL was removed from
kernels starting from 2.6.39
Looks like I need to re-build kernel with BKL enabled (if it's possible.
Not sure if it's possible). Other solution is to install CentOS6 it uses
kernels 2.6.x
What linux kernel do you use on your server with dadhi E1 adapters?
Thank you
Babanov Ivan
чт, 8 окт. 2020 г. в 20:30, Harald Welte <laforge(a)osmocom.org>rg>:
Hi Ivan,
On Thu, Oct 08, 2020 at 01:14:03AM +0300, Ivan Babanov wrote:
Brief question. Is it possible to debug E1 line
by connecting it to the
2nd
port of the same NIC making a wired loop?
well, you would normally need a series resistor for the tapping port, you
cannot
just put them in parallel without signal degradation.
You can check
https://osmocom.org/projects/e1-tap/wiki for a small OSHW
device that has the series resistors built in, and which provides two tap
ports (one for each direction). For full-duplex sniffing of one E1 line,
you
obviously need two other ports.
Is it enough to open->ioctl->read
from /dev/dahdi/channel to get a stream of LAPD SABME messages
transmitted
by BSC?
not /dev/dahdi/channel. On that device you need a special ioctl.
you could look into osmo-e1-recorder, if you wanted to do tracing with
DAHDI
ports behind a osmo-e1-tap.
I'm still trying to bring up BTS Nokia Flexi
with OSMO-BSC.
great.
I'm using an E1 card Digium TE405P on the
server side.
OSMO-BSC is connected with Nokia BTS via a single E1 line.
Looks like on Level1 everything is ok because BTS can detect the link and
raise an alarm if the wire is getting disconnected.
great.
I can observe some data from timeslots on BTS
side and if some channel is
configured as D-Channel in /etc/dahdi/system I see transmission of block
"01111110".
that's the flag octets
But the problem is that LAPD link is not
establishing. I can't find any
tries on BTS side and BSC does not receive anything from BTS, just set of
SABME messages in PCAP file.
That's somewhat of a contradiction.
* SABME is the first frame used to establish a LAPD data link
* it should be sent from BTS to BSC
* the BSC responds with UA
T200 expires and so on. I tried various T200
values. So, now it looks for
me like L1 does not receive anything from L2 on BSC side and nothing is
transmitted over the wire to BTS.
it would be useful to see your configs. I would guess most likely you
didn't select the same timeslot for
signaling on both sides.
--
- Harald Welte <laforge(a)osmocom.org>
http://laforge.gnumonks.org/
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