Events: Q931

Event structure

 Explanation of protocol events.

Q931 decoding

 Using the Clarinet Event-Editor and an appropriate filter.

Protocol stack

 Defining a list of protocols used in the current filter.

Standards
  • ITU Recommendation Q931
  • ETSI ETS 300 403

Options

Changing the display format in the current filter.

Clarinet Event-Editor: Q931 decoding

q931_isdn_det123.gif (19970 octets)

Event information

Date:

Date of the event (end of BOP frame) in the format: hh:mm:ss/xxx.y

N

 The interface number which identifies the Clarinet-interface connected to the host.

Link type
  • TS: Signalling Link Transmit direction
  • RS: Signalling Link Receive direction
  • TD: Data Link Transmit direction
  • RD: Data Link Receive direction

Dx

 The decoding level as specified in the filter (protocol stack).

Protocol fields

BOP

 <BOP type> <flag counter>    [nnnn]

Q921

 (Address) <PDU type> Ctrl    [nnnn]

Q931

 Pro-Id  CallRef  <PDU type>
Ctrl

Q931 Protocol fields

Pro-Id

 Protocol discriminator 08h.

CallRef

 Call reference in the following format: Ref:(x,yy) or Ref:(x,yy yy)

x

 O (origin) or D (destination).

yy or yy yy

 Reference number in hexadecimal; 1 octet in BRI (S0/T0 or U), 2 octets in PRI (E1 or T1).

<PDU_type>

 Type of message.

Ctrl

 Attached IE's are displayed according to the the display mode selected in the filter :
Identified mode IE:(c/xx) len:y >> designation
value
Detailed mode IE:(c/xx) len:y >> designation
octet 3 : ......
octet i : bkl field
              ......
octet j : info
octet n : ......
Data field length = 0 no IE display

ASN.1 decoding of an IE content can be displayed either in detailed or BER mode.

c

 Codeset.

xx

 IE code (octet 1).

y

 Length of IE content (from octet 3).

designation

 Designation of IE according to the standard.

value

 Only with Identified mode, IE content (from octet 3) in hexadecimal.

bkl_field

 Only with Detailed mode, every field is displayed with it's bit configuration within the relevant octet and it's meaning according to the standard.

info

 Only with Detailed mode, conveyed information.

Protocol stack applied

q931_isdn_stack.gif (7333 octets)

 

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