[asterisk-ss7] Some Channels are Blocked with remote maintanence

Gregory Massel greg at csurf.co.za
Mon Nov 21 06:11:18 CST 2011 

Looking at l4isup.c and the dump, I'm just wondering, is it correct 
behaviour to have an empty optionals section?

e.g. code like the following in isup_send_rlc():
isup_msg_start_optional_part(msg, sizeof(msg), &varptr, &current);
isup_msg_end_optional_part(msg, sizeof(msg), &current);

Should this not just be stripped out?

Similar code exists in isup_send_rel(), except that optionals are added 
in the event of certain if() conditions being matched. Again, the 
question I have is should the isup_msg_start_optional_part and 
isup_msg_end_optional_part functions even be called if the conditions 
are such that no optionals need to be added?

--Greg

On 2011/11/21 01:36 PM, Gregory Massel wrote:
> I have the exact same condition with chan_ss7 on Asterisk 1.4 and 
> Asterisk 1.8 and can confirm that I've run all versions of chan_ss7 
> from 1.3 up to 2.1.0 (2.1.0 on Asterisk 1.8 and the previous versions 
> on Asterisk 1.4).
>
> The remote end is, to the best of my knowledge, a Siemens EWSD.
>
> The following feedback was provided by the remote carrier and may 
> prove useful in explaining the problem:
>
> SWTNRB     26    1-26  TRUNK    BW      0-24 2-26   IDLE
>
> SWTNRB     27    1-27  TRUNK    BW      0-24 2-27   INC &
>
>                                                     FRCD &
>
>                                                     IALM
>
> SWTNRB     28    1-28  TRUNK    BW      0-24 2-28   IDLE
>
> SWTNRB     29    1-29  TRUNK    BW      0-24 2-29   INC &
>
>                                                     FRCD &
>
>                                                     IALM
>
> SWTNRB     30    1-30  TRUNK    BW      0-24 2-30   IDLE
>
> With the IALM condition is caused by "end of optional parameter in the 
> wrong place".
>
> If you should see in the attachment I have highlighted the REL and RLC 
> message from your nodes.
>
> Both of these have the optional parameter "indicated".
>
> If it is possible can you please  set optional parameters OFF ( 
> parameter indicator =0) for
>
> These two messages.
>
> If you can let me know so that we can reset the circuits as we have 
> done previously.
>
>
> They also provided the following:
>
> --------------------------------------------------------------------------------
>
> Octet001 ITU-T SS7 Count=000001 Time=08/22/2011 13:21:14:023
>
> --------------------------------------------------------------------------------
>
> 10010010 BIB/BSN (146) 1/18
>
> 11111001 FIB/FSN (249) 1/121
>
> ..001110 SU type/length (14) MSU14
>
> 00...... Spare 0
>
> --------------------------------------------------------------------------------
>
> Octet004 Service information octet
>
> --------------------------------------------------------------------------------
>
> ....0101 Service indicator (5) ISUP ISDN User Part
>
> ..00.... Message priority 0
>
> 11...... Network indicator (3) NAT1 National network
>
> --------------------------------------------------------------------------------
>
> Octet005 Routing label
>
> --------------------------------------------------------------------------------
>
> ........ DPC 01-1-03-0 JNL#1
>
> ........ OPC 00-6-01-0 SWITCHTEL
>
> 1001.... SLS 9
>
> --------------------------------------------------------------------------------
>
> Octet009 Circuit identification code
>
> --------------------------------------------------------------------------------
>
> ........ CIC 217
>
> 0000.... Spare 0
>
> --------------------------------------------------------------------------------
>
> Octet011 ISUP Release message
>
> --------------------------------------------------------------------------------
>
> 00001100 Message type (12) REL Release
>
> 00000010 Pointer->cause 2
>
> 00000100 Pointer->optionals 4
>
> --------------------------------------------------------------------------------
>
> Octet014 Cause indicators parameter
>
> --------------------------------------------------------------------------------
>
> 00000010 Parameter length 2
>
> ....0101 Location (5) Private network serving the remote user (RPN)
>
> ...0.... Spare 0
>
> .00..... Coding standard (0) CCITT standard
>
> 1....... Extension bit (1) Last octet
>
> .0010000 Cause (16) Normal call clearing
>
> 1....... Extension bit (1) Last octet
>
> --------------------------------------------------------------------------------
>
> Octet017 ISUP End of optional parameters
>
> --------------------------------------------------------------------------------
>
> 00000000 Parameter name code (0) ISUP End of optional parameters
>
> --------------------------------------------------------------------------------
>
> Checksum CRC16................ 0001110100001111 hex=1D0F
>
> --------------------------------------------------------------------------------
>
>
>
> As far as I am aware, there is no way to disable the optionals in 
> chan_ss7.
>
> Interestingly, the is not on all REL and RLC messages, only some of them.
>
> I guess it's time to look through the source code, but this hasn't 
> proven terribly problematic for me thus far because it's only a few 
> random CICs that block in that state. It seems the remote end does 
> eventually remove the admin block by itself after a certain amount of 
> time, but restarting asterisk or chan_ss7 won't help. Usually I just 
> get the guys on the remote end to manually clear the condition.
>
> On 2011/11/21 10:35 AM, Stefan Schmidt wrote:
>> Hello list,
>>
>> i have two E1 running on a asterisk 1.8 with chan_ss7 which i have set
>> to production state last week. And after around 5000 calls i can see
>> that 3 channels are in state BLOCKED Remote Maintenance. My carrier said
>> he hasnt blocked anything on this two E1 lines but he can see some
>> messages even on busy lines he doesnt understand.
>>
>> Asterisk was automatically restarted every night but these three
>> channels stay at this state.
>>
>> Is this a known bug or what can i do to solve this problem?
>>
>> asterisk verison 1.8 (Asterisk SVN-schmidts-unleash-the-beast-r343849)
>> chan_ss7 version (chan_ss7 version 2.1.0) but with some patches to isup
>> for connected line information and also the patch for the additional
>> calling party header.
>>
>> thanks!
>>
>> best regards
>>
>> stefan schmidt
>>
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