D-Channel Monitoring
LD 96 is used to test and maintain D-channel (DCH) links.
D-Channel message monitoring is used to analyze the Layer 3 protocol messages travelling between the near and far-end D-channels. This is very useful for checking incoming/outgoing digit patterns, or investigating why a call is failing. See also: Cause Codes (ISDN).
Notes:
- During high traffic periods, some of the monitored messages may be lost.
- For the D-Channel messages to be displayed, the TTY port must have USER MTC in LD 17: ADAN.
- D-Channel message monitoring can produce a lot of output, so always remember to disable it when finished!
Use the following commands in LD 96:
| Command | Description |
|---|---|
| STAT DCH x | Display status of D-channel x. Omit x to display status of all D-channels |
| STAT MON x | Display the incoming and outgoing monitoring status of one or all D-channels |
| ENL MSGI x | Enable the monitoring of all incoming messages from D-channel x |
| ENL MSGO x | Enable the monitoring of all outgoing messages for D-channel x |
| DIS MSGI x | Disable the monitoring of incoming messages from D-channel x |
| DIS MSGO x | Disable the monitoring of outgoing messages from D-channel x |
| SET MSGI x MON (0)-2 | Set monitor output format level for all incoming messages on D-channel x * |
| SET MSGO x MON (0)-2 | Set monitor output format level for all outgoing messages on D-channel x |
| ENL MON TTY | Enable DCH messages output to TTY (must have USER MTC) |
| ENL MON LOG | Enable DCH messages output to log file:/u/trace/dch.log |
| DIS MON TTY | Stop printing DCH messages on the TTY |
| DIS MON LOG | Stop logging DCH messages into log file |
* There are three levels of message decoding, 0-2.
Usually we want level zero, which is the easiest to read. Level 1 outputs raw data, and Level 2 is in HEX. To change the output message level to plain text, use: SET MSGI x MON 0
Once enabled, messages can be sent to the TTY, a log file, or both. Use the LD 96 command STAT MON to determine which channels have monitoring enabled, and where the output will be sent:
.stat mon
TRACE OUTPUT
DCH LOG : OFF
DCH TTY : ON ← if OFF, enable output with ENL MON TTY
ACTIVE TRACES
DCH 200 : MSGI - ENBL MSGO - ENBL ← in/out monitoring for this DCH enabled
DCH 211 : MSGI - DSBL MSGO - DSBL (UIPE)
DCH 212 : MSGI - DSBL MSGO - DSBL (UIPE)
The trace output will be sent to the TTY. If set to OFF, enable it with enl mon tty
To send the output to a log file: enl mon log, or both log file and TTY: enl mon all.
The log file is located at: /u/trace/dch.log and can be downloaded from the Call Server by FTP.
Refer to Cause Codes (ISDN) (Avaya/Nortel) and/or ISDN (PRI) Cause Codes (Standard Q.931) for Cause Code definitions.
The most commonly seen call clearing cause codes are 16 (normal disconnect or cleardown) and 17 (user busy).
Determine the D channel number:
Use STAT in LD 60 to identify the PRI circuit, the CH31 position shows the associated D channel number.
.stat
PRI2 LOOP 12 - ENBL
REF CLK: ENBL
TRACKING
SERVICE RESTORE: YES
ALARM STATUS: ACCEPTABLE
CH 01 - IDLE DID VOD * CH 02 - IDLE DID VOD *
CH 03 - IDLE DID VOD * CH 04 - IDLE DID VOD *
CH 05 - IDLE DID VOD * CH 06 - IDLE DID VOD *
CH 07 - IDLE DID VOD * CH 08 - IDLE DID VOD *
CH 09 - IDLE DID VOD * CH 10 - IDLE DID VOD *
CH 11 - IDLE DID VOD * CH 12 - IDLE DID VOD *
CH 13 - IDLE DID VOD * CH 14 - IDLE DID VOD *
CH 15 - IDLE DID VOD * CH 16 - IDLE DID VOD *
CH 17 - IDLE DID VOD * CH 18 - IDLE DID VOD *
CH 19 - IDLE DID VOD * CH 20 - IDLE DID VOD *
CH 21 - IDLE DID VOD * CH 22 - IDLE DID VOD *
CH 23 - IDLE DID VOD * CH 24 - IDLE DID VOD *
CH 25 - IDLE DID VOD * CH 26 - IDLE DID VOD *
CH 27 - IDLE DID VOD * CH 28 - IDLE DID VOD *
CH 29 - IDLE DID VOD * CH 30 - IDLE DID VOD *
CH 31 - DCH 6 ⇐ D channel number for this PRI
.
In this case, its DCH 6, so we will enable messages on DCH 6.
Message monitor:
To enable incoming and outgoing message monitoring for a PRI's D channel:
>ld 96 DCH000 .enl msgi 6 ⇐ enable display of incoming messages for the PRI D channel number .enl msgo 6 ⇐ enable display of outgoing messages for the PRI D channel number
As monitoring D channel messages can produce a lot of TTY output, we can filter the output to show (up to 3) specific message types:
ENL MSGI x MSG <msg1> <msg2> <msg3> - For example: enl msgi 6 msg cona will show only 'connect acknowledge' messages.
Refer to the table below for message type definitions (if not specified, default is ALL).
- ALER - alerting
- ALL - all messages
- CAPR - call proceeding
- CON - connect
- CONA - connect ack
- DISC - disconnect
- FAC - facility
- FACA - facility ack
- FACR - facility reject
- INFO - information
- NOTF - notify
- PRIM - all primitives
- PROC - call proceeding
- PROG - progress
- RLS - release
- RLSC - release complete
- RST - restart
- RSTA - restart ack
- STAT - status
- STEN - status enquiry
- STP - setup
- STPA - setup ack
- SVC - service
- SVCA - service ack
- UI - user information
Be sure to disable monitoring when you're finished.
.dis msgi 6 ⇐ disable display of incoming messages for the PRI D channel number .dis msgo 6 ⇐ disable display of outgoing messages for the PRI D channel number
Example D channel message output:
- DCH X - D channel number
- IMSG - incoming message
- OMSG - outgoing message
- REF - unique call reference number
- CH - channel/timeslot designation
- TOD - time of day stamp
The unique call reference number
(REF) denotes the same call for its duration.
>ld 96 DCH000 .enl msgi 6 .enl msgo 6 . DCH 6 UIPE_IMSG CC_INFO_IND REF 0000002A CH 6 30 TOD 11:37:50 DCH 6 UIPE_IMSG CC_FAC_IND REF 0000002A CH 6 30 TOD 11:37:50 DCH 6 UIPE_OMSG CC_SETUP_REQ REF 0000002B CH 6 28 TOD 11:37:58 PROGRESS: ORIGINATING END IS NOT ISDN CALLING #:3699 NUM PLAN: E164 CALLED #:06975353888 NUM PLAN: E164 DCH 6 UIPE_IMSG CC_PROCEED_IND REF 0000002B CH 6 28 TOD 11:37:58 DCH 6 UIPE_IMSG CC_ALERT_IND REF 0000002B CH 6 28 TOD 11:38:00 PROGRESS: INBAND INFO OR PATTERN IS AVAIL DCH 6 UIPE_OMSG CC_DISC_REQ REF 0000002B CH 6 28 TOD 11:38:02 CAUSE: #16 - NORMAL CALL CLEARING DCH 6 UIPE_IMSG CC_RELEASE_IND REF 0000002B CH 6 28 TOD 11:38:02 DCH 6 UIPE_OMSG CC_RELEASE_RESP REF 0000002B CH 6 28 TOD 11:38:02 DCH 6 UIPE_IMSG CC_INFO_IND REF 00000028 CH 6 29 TOD 11:38:08 DCH 6 UIPE_IMSG CC_FAC_IND REF 00000028 CH 6 29 TOD 11:38:08 DCH 6 UIPE_IMSG CC_INFO_IND REF 0000002A CH 6 30 TOD 11:38:10 DCH 6 UIPE_IMSG CC_FAC_IND REF 0000002A CH 6 30 TOD 11:38:10 DCH 6 UIPE_OMSG CC_DISC_REQ REF 0000002A CH 6 30 TOD 11:38:26 CAUSE: #16 - NORMAL CALL CLEARING DCH 6 UIPE_IMSG CC_RELEASE_IND REF 0000002A CH 6 30 TOD 11:38:26 DCH 6 UIPE_OMSG CC_RELEASE_RESP REF 0000002A CH 6 30 TOD 11:38:26 DCH 6 UIPE_IMSG CC_DISC_IND REF 00000028 CH 6 29 TOD 11:38:54 CAUSE: #16 - NORMAL CALL CLEARING PROGRESS: INBAND INFO OR PATTERN IS AVAIL .dis msgi 6 .dis msgo 6
About the messages:
Q.931 messages control or report the status of ISDN connections. For example:
SETUP- indicating the establishment of a connectionCALL PROCEEDING- indicating that the call is being processed by the destination terminalALERTING- tells the calling party that the destination terminal is ringingCONNECT- sent back to the calling party indicating that the intended destination has answered the callDISCONNECT- sent to indicate a request to terminate the connection, by the end that seeks to terminateRELEASE- sent in response to the disconnect request indicating that the call is to be terminatedRELEASE COMPLETE- sent by the receiver of the release to complete the handshake
Nortel/Avaya use a proprietary 'Universal ISDN Protocol Engine' (UIPE) which supports worldwide ISDN variants. D channel hardware (MSDL, etc) must download a configuration specific localised UIPE via the PSDL (force download: FDL) after a DCH is built or changed.
UIPE (Universal ISDN Protocol Engine) messages, and Q.931 equivalents:
- UIPE Outgoing messages are either a REQUEST (REQ) or a RESPONSE (RESP)
- UIPE Incoming messages are either an INDICATION (IND) or a CONFIRMATION (CONF)
Q.931 Message UIPE Outgoing Message UIPE Incoming Message ALERTING CC_ALERT_REQUEST CC_ALERT_INDICATION CALL PROCEEDING CC_PROCEEDING_REQUEST CC_PROCEEDING_INDICATION PROGRESS CC_PROGRESS_REQUEST CC_PROGRESS_INDICATION SETUP CC_SETUP_REQUEST CC_SETUP_INDICATION CONNECT ACK CC_SETUP_RESPONSE CC_SETUP_CONFIRMATION DISCONNECT CC_DISCONNECT_REQUEST CC_DISCONNECT_INDICATION FACILITY CC_FAC_REQUEST CC_FAC_INDICATION FACILITY CC_FAC_REG_NULL_CRF CC_FAC_IND_NULL_CRF FACILITY REJECT CC_FACREJ_REQ_NULL_CRF CC_FACREJ_IND_NULL_CRF NOTIFY CC_NOTIFY_REQUEST CC_NOTIFY_INDICATION RELEASE CC_REJECT_REQUEST CC_REJECT_INDICATION RELEASE CC_RELEASE_REQUEST CC_RELEASE_INDICATION RELEASE COMPLETE CC_RELEASE_RESPONSE CC_RELEASE_CONFIRMATION RESTART CC_RESTART_REQUEST CC_RESTART_INDICATION RESTART ACK CC_RESTART_RESPONSE CC_RESTART_CONFIRMATION SERVICE SERVICE MESSAGES SERVICE MESSAGES SERVICE SERVICE RESPONSE SERVICE RESPONSE SETUP ACK CC_MORE_INFO_REQUEST CC_MORE_INFO_INDICATION STATUS CC_STATUS_REQUEST CC_STATUS_INDICATION STATUS ENQUIRY CC_STATUS_ENQ_REQUEST CC_STATUS_ENQ_INDICATION INFORMATION CC_INFORMATION_REQUEST CC_INFORMATION_INDICATION
Hex To ASCII Converter:
This converter can be useful for deciphering certain messages. Copy/paste, and convert.