[asterisk-users] Best timing source?

Duncan duncan at e-simple.co.nz
Wed Apr 6 16:20:33 CDT 2016

On 07/04/16 09:00, Carlos Chavez wrote:
> On 4/6/16 2:39 PM, Duncan Turnbull wrote:
>>>     I am starting to think that the problem may be in the server 
>>> hardware itself.  We are using a Dell R220 with 8gb of ram and 2 
>>> hard disks in a Raid 1 configuration (Linux Raid).  We are using 
>>> CentOS 7.  We had to remove the raid card from the server to install 
>>> an E1 card (the raid card was Windows only so no loss there really). 
>>> Internally everything sounds good (from E1 to a conference or music) 
>>> but once you hit a network interface we start getting pops and drops.
>>>     Anyone with this server and Asterisk ever had issues like these?
>> Just checking you have your E1 timing set to slave off the upstream. 
>> If not you are going to have E1 sync errors which will give you the 
>> voice problems you describe
>     Dahdi_test gives me a 99.97% average.  The problem is present on 
> all calls (except calling into the E1 to a conference or to MoH).  I 
> am preparing a new server to see if it is a hardware issue.
This is the bit I mean, but if you have calls going over the E1 that are 
okay then its probably not this.


|# span=<span num>,<timing source>,<line build out 
(LBO)>,<framing>,<coding>[,yellow] # # All T1/E1 spans generate a clock 
signal on their transmit side. The # <timing source> parameter 
determines whether the clock signal from the far # end of the T1/E1 is 
used as the master source of clock timing. If it is, our # own clock 
will synchronise to it. T1/E1's connected directly or indirectly to # a 
PSTN provider (telco) should generally be the first choice to sync to. 
The # PSTN will never be a slave to you. You must be a slave to it. # # 
Chose 1 to make the equipment at the far end of the E1/T1 link the 
preferred # source of the master clock. Chose 2 to make it the second 
choice for the master # clock, if the first choice port fails (the far 
end dies, a cable breaks, or # whatever). Chose 3 to make a port the 
third choice, and so on. If you have, say, # 2 ports connected to the 
PSTN, mark those as 1 and 2. The number used for each # port should be 
different. # # If you choose 0, the port will never be used as a source 
of timing. This is # appropriate when you know the far end should always 
be a slave to you. If the # port is connected to a channel bank, for 
example, you should always be its # master. Any number of ports can be 
marked as 0. # # Incorrect timing sync may cause clicks/noise in the 
audio, poor quality or failed # faxes, unreliable modem operation, and 
is a general all round bad thing. |

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