Command:

debug isdn q931


Mode:

Router#


Syntax:

debug isdn q931

no debug isdn q931

 

Syntax Description:

This command has no arguments or keywords.

 

Command Description:

To display information about call setup and teardown of ISDN network connections (layer 3) between the local router (user side) and the network, use the debug isdn q931 privileged EXEC command. The no form of this command disables debugging output.

The ISDN network layer interface provided by the router conforms to the user interface specification defined by ITU-T recommendation Q.931, supplemented by other specifications such as for switch type VN4. The router tracks only activities that occur on the user side, not the network side, of the network connection. The display information debug isdn q931 command output is limited to commands and responses exchanged during peer-to-peer communication carried over the D channel. This debug information does not include data sent over the B channels, which are also part of the router’s ISDN interface. The peers (network layers) communicate with each other via an ISDN switch over the D channel.

A router can be the calling or called party of the ISDN Q.931 network connection call setup and tear-down procedures. If the router is the calling party, the command displays information about an outgoing call. If the router is the called party, the command displays information about an incoming call.

You can use the debug isdn q931 command with the debug isdn event and the debug isdn q921 commands at the same time. The displays will be intermingled. Use the service timestamps debug datetime msec global configuration command to include the time with each message.


Example:

The following is sample output from the debug isdn q931 command of a call setup procedure for an outgoing call:

Router# debug isdn q931
TX -> SETUP pd = 8 callref = 0x04
Bearer Capability i = 0x8890
Channel ID i = 0x83
Called Party Number i = 0x80, ‘415555121202’
RX <- CALL_PROC pd = 8 callref = 0x84
Channel ID i = 0x89
RX <- CONNECT pd = 8 callref = 0x84
TX -> CONNECT_ACK pd = 8 callref = 0x04....
Success rate is 0 percent (0/5)


Misconceptions:

The ISDN switch provides the network interface defined by Q.921. This debug command does not display data link layer access procedures taking place within the ISDN network (that is, procedures taking place on the network side of the ISDN connection).


Related Commands:

None.


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