Physical Layer

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The first step in troubleshooting any connectivity issue is troubleshooting the physical layer. Identifying whether a user has a physical layer issue is by using the TDM Status page and checking the MTP-1 column. If the column is listed as "DOWN" for that particular port, you must proceed with troubleshooting the physical layer.

When the physical layer is down, all layers above the physical layer will also be in a "DOWN" or "TRYING" state.

In order to start troubleshooting, the user must proceed to the "Command Execution" page, which is located under the "Operation" column.

Once the user clicks on the Command Execution link, they will be presented with the following screen as below:

The best way to troubleshoot physical layer issues is through the shell command option. Below is a list of commands that can be run within the shell command section to help diagnose issues:

Linux Commands:

• ifconfig 
  Displays all network interfaces
  Sangoma interfaces start with "w"  eg: "w1g1" for span1, "w2g1" for span2 ...  
• cat /proc/interrupts
  Displays the interrupt status for all cpu and devices 
• hdparm -t /dev/sda
  Check for disk access speed.  If speeds are less than 10MBps it could indicated that motherboard/chipset is not supported by Linux kenrel.  
• vmstat 
  Outputs system load information
  in = interrupt per timeout
  cs = context switching
  us = user load
  sy = system load (kernel)
  id = idle 

Sangoma TDM Driver related commands:

• wanpipemon -i wXg1 -c Ta (where X is the span number in question. Can also be found using ifconfig)
  Output low level T1/E1 Alarms 
• wanrouter status
  Output wanpipe physical status statistics

Wanpipe Port Status

The first step in debugging physical layer issues would be to check whether wanrouter status reports the line "Connected" or "Disconnected". To do this, within the "Shell Command" textbox, enter the command "wanrouter status". It will return a result like the one below:
-> wanrouter status 

All the devices running on a NSG system will be listed as a "wanpipe" device. In this example, "wanpipe1" is being reported as "Disconnected", which tells us that the physical layer is in fact in a "DOWN" state.

 

Wanpipe Port T1/E1 Alarms

The next step would be to check where the issue lies.
To do this, the user would need to run the command "wanpipemon -i wXg1 -c Ta"
                                                                                      (where X stands for the wanpipe number).
In this example, "wanpipe1" is in a disconnected state, therefore the interface name would be "w1g1".
The command returns an output similar to the one below:
->  wanpipemon -i w1g1 -c Ta

1. First check the Rx Level
   The correct value is -2.5db
   Anything other than -2.5db indicates that there is a problem with the line.
   
   Options
   -2.5db - rx level is perfect
   -10db to -20db - there is something on the line but very weak. Could indicated a cable problem.
   -44db  - there is nothing on the line.  Either line is not started or there is no clock on the line.
   
   Sangoma cards will not come up if there is no clock on the line.
   One way to confirm that Telco is not giving us the clock, is to go back to TDM Physical Configuration section and
   configure the TDM Port for Master T1/E1 Clock.   Note: Telco should always supply the clock.
2. Rx Alarms
   
   Rx Alarms indicated that there is something wrong on the line
   RED - We are not receiving any kind of signal on the line.  
             Usually indicates that the line is not active.
   AIS  - The remote end is keeping us down on purpose
             Line in maintenance
   RAI  - We receive good signal from remote end, but remote end does not see a good signal from us.
             Thus remote end is down.
3. Short/Open Circuit
   
   These statistics usually indicate cable issues.  
   Or that the port is not plugged in at all.
   (Which in this example is the case)

For a description on what each alarm description and meaning, please see the following link: http://wiki.sangoma.com/Wanpipemon-T1-E1-physical-Line-alarms