[asterisk-ss7] chan_ss7 MTP is now Down after 70 calls.

[Robert Thomas]

Hello Everyone,


We have a 7 E1 SS7 linkset that above 70 calls load starts to flap
constantly. The MTP goes down, and comes back after 10 seconds or so.
Sometimes it goes up and down a few times in a row.  The flaps occur every
few minutes. We believe the TELCO is sending an LSSU message with an OS
flag, because of a weird behavior or instability in our side that we are
trying to determine.


We can see a lot of errors like:


[Jun 28 01:53:30] NOTICE[31874] l4isup.c: read() failure, errno=11: Resource
temporarily unavailable
[Jun 28 01:53:27] NOTICE[31876] mtp.c: Got event on link 'ostional1': 8
(0/11).

[Jun 28 01:53:32] NOTICE[31874] l4isup.c: read() failure, errno=11: Resource
temporarily unavailable

[Jun 26 15:37:52] NOTICE[31191] l4isup.c: Short read on linkset "ostional"
CIC=153 (read only 0 of 160) errno=11 (Resource temporarily unavailable)
(supressed 953093).


Happening around seconds of a flap condition. This issue is reproducible and
occurs quite often.
The link has no alarms, and can run stable for hours with no load. With 30
or more calls the link behaves stable.

Asterisk 1.6.2.18

ChanSS7 2.0

dahdi-linux-complete-2.4.1.2+2.4.1

TE410P and TE420P

[Jun 28 01:53:26] WARNING[9424] dsp.c: Inband DTMF is not supported on codec
g729. Use RFC2833

*This call was the last one been processed*

*We seem to get a bunch of these errors:*

[Jun 28 01:53:27] NOTICE[31876] mtp.c: Got event on link 'ostional1': 8
(0/11).

[Jun 28 01:53:27] NOTICE[31876] mtp.c: Got event on link 'ostional1': 8
(0/11).

*These errors are less common*

[Jun 28 01:53:27] NOTICE[31874] l4isup.c: read() failure, errno=11: Resource
temporarily unavailable

[Jun 28 01:53:27] NOTICE[31876] mtp.c: Got event on link 'ostional1': 8
(0/11).

… *Many more of this errors*

*At some point we received the LSSU with OS from the TELCO and the link
changes to down** *

[Jun 28 01:53:27] NOTICE[31876] mtp.c: Got status indication 'OS' while
INSERVICE on link 'ostional1'.

[Jun 28 01:53:27] WARNING[31876] chan_ss7.c: MTP is now DOWN on link
'ostional1'.

[Jun 28 01:53:27] NOTICE[31876] mtp.c: MTP changeover last_ack=7,
last_sent=7, from schannel 31, no INSERVICE schannel found

[Jun 28 01:53:27] NOTICE[31876] mtp.c: Failover not possible, no other
signalling link and no other host available.

[Jun 28 01:53:27] WARNING[31876] chan_ss7.c: MTP is now DOWN on link
'ostional1'.

[Jun 28 01:53:27] NOTICE[31876] mtp.c: Got status indication 'OS' while
INSERVICE on link 'ostional2'.

[Jun 28 01:53:27] WARNING[31876] chan_ss7.c: MTP is now DOWN on link
'ostional2'.

[Jun 28 01:53:27] NOTICE[31876] mtp.c: MTP changeover last_ack=11,
last_sent=12, from schannel 31, no INSERVICE schannel found

[Jun 28 01:53:27] NOTICE[31876] mtp.c: Failover not possible, no other
signalling link and no other host available.

[Jun 28 01:53:27] WARNING[31876] chan_ss7.c: MTP is now DOWN on link
'ostional2'.

[Jun 28 01:53:27] NOTICE[31876] mtp.c: Got event on link 'ostional1': 6
(0/11).

…

[Jun 28 01:53:27] NOTICE[31876] mtp.c: Got event on link 'ostional1': 6
(0/11).

[Jun 28 01:53:28] NOTICE[31874] l4isup.c: read() failure, errno=11: Resource
temporarily unavailable
[Jun 28 01:53:29] NOTICE[9244] l4isup.c: Short read on linkset "ostional"
CIC=101 (read only 0 of 160) errno=11 (Resource temporarily unavailable)
(supressed 1822).
*
Some seconds later the link will come back*

Jun 28 01:54:08] WARNING[31876] chan_ss7.c: MTP is now UP on link
'ostional2'.

[Jun 28 01:54:08] NOTICE[31876] mtp.c: Sending TRA to peer on link
'ostional2'....

[Jun 28 01:54:08] WARNING[31876] chan_ss7.c: MTP is now UP on link
'ostional1'.

[Jun 28 01:54:08] NOTICE[31876] mtp.c: Sending TRA to peer on link
'ostional1'....

[Jun 28 01:54:11] NOTICE[31876] l4isup.c: T1 timeout (waiting for RLC)
CIC=175.

[Jun 28 01:54:18] NOTICE[31876] l4isup.c: T1 timeout (waiting for RLC)
CIC=59.

[Jun 28 01:54:18] NOTICE[31876] l4isup.c: T1 timeout (waiting for RLC)
CIC=101.
**

*We can see calls coming in again*

What conditions could generate the CO Switch to send an LSSU with an OS
signal.

Could this because of line errors, slips or problems on the line? How could
we check that from the asterisk side?

-- 

Robert
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