E1/T1 Line Alarms

Owned by Nathaniel Halbrooks
Jan 08, 2024
4 min read

The following wanpipemon command can be used to view any alarms indicated on the physical T1/E1 line plugged into the port(s):

-> wanpipemon -i <interface> -c Ta

(interface values for the command above are w1g1 (port 1), w2g1 (port 2), w3g1 (port 3)...etc.  Replace '<inteface>' with your interface value (ex. wanpipemon -i w1g1 -c Ta)

First make sure that wanrouter is started:

-> wanrouter start

Otherwise an error will prompt saying: 
Ioctl: : No such device 

 

Below is a sample output of wanpipemon for an E1 interface w1g1

wanpipemon -i w1g1 -c Ta    ***** w1g1: E1 Rx Alarms (Framer) ***** ALOS: OFF  |  LOS:  OFF RED:   OFF  |  AIS:  OFF LOF:    OFF  | RAI:  OFF ***** w1g1: E1 Rx Alarms (LIU) ***** Short Circuit: OFF Open Circuit: OFF Loss of Signal: OFF ***** w1g1: E1 Tx Alarms ***** AIS: OFF | YEL: OFF    ***** w1g1: E1 Performance Monitoring Counters ***** Line Code Violation : 330 Far End Block Errors : 4215 CRC4 Errors : 0 FAS Errors : 3   Rx Level : > -2.5db

 

As noticed, the alarms are split in 3 different categories:
->Rx Framer alarms
->Rx (LIU) alarms
->Performance Monitoring Counters

 

Below is a description of each Alarm:

RED

Indicates the device is in alarm 

LOF

(Loss of Framing).  Raised after four consecutive frames with FAS error.  If RAI and AIS alarms are not indicated, verify that you have selected the proper line framing (i.e T1: ESF, D4, E1:CRC4, NCRC4..etc)  

LOS

(Loss Of frame Signal)

AIS

(Alarm Indication Signal): typicall know as a BLUE Alarm. all-ones signal transmission to the receivingequipment (the Sangoma card) to indicate that an upstream repeater (telco equipment) is in alarm, due to upstream transmission fault, either from another repeater or from the telco itself. If the onlyalarms indicating in the wanpipemon output is AIS:ON, then contact your telco with this information (RAI:ON can also be a possibility in this case as well) 
Example call diagram of the scenario: Sangoma card <---------------repeater <--------------Telco

RAI

(Remote Alarm Indication): Indicates that the Far end (typically the Telco) is in RED alarm state and sending that message over the line.  If the only alarm in your wanpipemon output is RAI:ON then contact your telco with this information.

You will also get this alarm, and only this alarm, if your framing is incorrect.This setting can be changed in the wanpipeX.conf file.

Short Circuit

 the wires in your cable connected to the port are crossed.  If you see this alarm, check the pinouts for the cable you are using. You may also be plugging in the wrong form of cable (straight-through, or cross-over) 

Open Circuit

 No line plugged into the port.  Make sure that your connector is plugged in and the wiring is making a good connection.  If this alarm is on, you will also Rx Level='-36'->'-44'. 

Loss of Signal

 Cabling issue.  Check the health of the cable plugged into the port, as well as its connection to the port it is plugged into.  You will also see the Rx Level either very low, or in a disconnected state: -36 -> -44.  It is typical to have this alarm triggers in combination with 'Open Circuit' if there is an issue with the physical connection 

YEL

When the equipment enters a Red-Alarm state, it returns a Yellow-Alarm back up the line of the received OOF. A typical scenario would be mis-configuration during the Sangoma card configuration (i.e selected CRC4 vs NCRC4).  In this type of scenario also LOF and RED alarms will be triggered.

Line Code Violation

 This occurs upon a bipolar violation

Far End Block Errors

is reported by the upstream end of the PHY (the wire between you and the switch) on the out-of-band management channel. This means the other end of the line received bad data from you.  Possible reason are: line noise, corroded wires..etc.  Also, check line Framing (E1: CRC4 vs NCRC4)

CRC4 Errors

 This occurs when the CRC polynomial calculation performed before transmission does not match the CRC calculation done upon reception.

FAS Errors

 (Frame alignment signal error). One or more incorrect bits in the alignment word

Rx Level

 Signal strength of the connection between the Sangoma card and the other end.  Health connection will show -2.5db.  If you notice your connection lower (i.e. -10db-->-12db, or -36fb, -44 db) Then check the cable or possibly replace it.  If the Rx level is very low, it can trigger Loss of Signal Tx, or even Open Circuit tx.

 

Wanpipe Port T1/E1 Alarms

In this example, "wanpipe1" is in a connected state, therefore the interface name would be "w1g1". 
The command returns an output similar to the one below:

->  wanpipemon -i w1g1 -c Ta

 

 

wanpipemon -i w1g1 -c Ta    ***** w1g1: E1 Rx Alarms (Framer) ***** ALOS: OFF  |  LOS:  OFF RED:   OFF  |  AIS:  OFF LOF:    OFF  | RAI:  OFF ***** w1g1: E1 Rx Alarms (LIU) ***** Short Circuit: OFF Open Circuit: OFF Loss of Signal: OFF ***** w1g1: E1 Tx Alarms ***** AIS: OFF | YEL: OFF    ***** w1g1: E1 Performance Monitoring Counters ***** Line Code Violation : 330 Far End Block Errors : 4215 CRC4 Errors : 0 FAS Errors : 3   Rx Level : > -2.5db

 

 

  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)

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