Events: Q921-LAPD

Event structure Explanation of protocol events.

Q921 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 Q921-LAPD
  • ETSI ETS 300 125

Options Changing the display conditions in the current filter.

Clarinet Event-Editor: Q921 decoding

q921_isdn_decod.gif (14207 octets)

q921_lic_isdn_decod.gif (10048 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 level of Decoding as specified in the filter (Stack).

Protocol fields Q921 (Address) <PDU type> Ctrl    [nnnn]

Service fields An optional string to display the fields conveyed by the UI frames (SAPI:63, TEI:127) under the format:

Management entity: M:xx R:xxxxx AI:(xxx)
Msg x: designation

Data field Raw data field displayed if no upper layer protocol is defined in the filter.
The display mode can be Hexa, Ascii or Ebcdic as specified in the filter.		  

Q921 Protocol fields

 (Address) Address field in the format (S:xx T:xxx C/R:x)
or (S:xx C:x L:xx yy zz) for extended address:
  S:xx SAPI value.
  T:xxx TEI value.
  C/R:x or C:x C/R bit value (0 or 1).
  L:xx yy zz Value of the extended address.
<PDU type> Type of frame.

Ctrl Control field in the format P/F:x NR:xxx NS:xxx :
  P:x or P/F:x Value of P or P/F bit (0 or 1).
  NR:xxx Value of NR (sequence Number Received).
  NS:xxx Value of NS (sequence Number Sent).
[nnnn] Length of the information frame data field (I or UI).

Service fields

 Field name  
  M:xx Management Entity Identifier.
  R:xxxxx Reference number.
  AI:(xxx) Action indicator.
  Msg x designation
x designation
1 Identity request
2 Identity assigned
3 Identity denied
4 Identity check request
5 Identity check response
6 Identity remove
7 Identity verify

Protocol stack applied

q921_isdn_stack.gif (7236 octets)

 

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