[asterisk-users] busy hangup HDLC Bad FCS (8) on Primary D-channel

[randall]

On 06/01/2011 06:28 PM, Steve Davies wrote:
> On 1 June 2011 15:10, randall <randall at songshu.org> wrote:
>> On 06/01/2011 03:55 PM, randall wrote:
>>> On 06/01/2011 03:41 PM, Tzafrir Cohen wrote:
>>>> On Wed, Jun 01, 2011 at 08:06:02AM +0200, randall wrote:
>>>>> Hi all,
>>>>>
>>>>> After running fine for a few months now asterisk seems to hang
>>>>> frequently , still functioning but the DAHDI channels seem busy  (users
>>>>> report a busy signal when calling or being called)
>>>>>
>>>>> A reboot will allow it to run for another day or maybe 2  or 3 till the
>>>>> problem occurs again.
>>>>>
>>>>>
>>>>> running stock Asterisk 1.6.2.9-2+squeeze2 on Debian with stock kernel
>>>>> 2.6.32-5-686
>>>>>
>>>>> i get the following errors:
>>>>> pri_dchannel: PRI got event: HDLC Bad FCS (8) on Primary D-channel of span 2
>>>>>
>>>>> (happens on all 4 spans)
>>>>>
>>>>> and the following in dmesg:
>>>>> [ 9004.635323] NOTICE-xpd_bri: XBUS-00/XPD-01: D-Chan RX DROP: BADFCS: 252
>>>>> [ 9004.635332] NOTICE-xpd_bri: XBUS-00/XPD-01: D-Chan RX:    current
>>>>> packet[0..2]: 55 55 FC
>>>>> [ 9004.635340] NOTICE-xpd_bri: XBUS-00/XPD-01: Multibyte Drop: errno=-71
>>>>>
>>>>>
>>>>> Channel 0/1, span 1 got hangup, cause 18
>>>>
>>>> Is this happening in the middle of a call? Or only a while after the
>>>> call ended?
>>>>
>>>
>>> the "bad fcs" messages seem to happen random
>> there seems to be a relation indeed, have seen them happen randomly
>> quite spurious, but they indeed tend to happen a while after the call is
>> made.
>>>
>>> the hangup happens when a call through DAHDI is attempted,
>>> (usually after it has been working fine for a while a day or 2)
> 
> In my experience, FCS errors are caused by line quality issues, and
> usually (not always) are in the telco's equipment. If they are only
> happening occasionally, it may be a marginal, but mostly-OK signal on
> the wire.
> 
> Do you also get occasional poor-quality audio on calls? The issue will
> happen more when a call is being setup, or is progressing because
> there are more frames being exchanged when a call is in progress.

audio quality seems to be fine ( e.g. had no complaints about that)

> 
> I have also seen a bad component or dry solder on a voice card cause
> this, and even a badly made ISDN cable can be part of the problem. If
> none of that helps, I would ask the telco to put a trace on the line.

would these FCS errors cause the system to become unresponsive leading
to "Channel 0/1, span 1 got hangup, cause 18" after a period of working
fine, or is this an unrelated issue?


> 
> Hope that helps,
> Steve
> 
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