Recommendation Q.921 (03/93) i
CONTENTS
Recommendation Q.921 (03/93)
Page
1 General ........................................................................................................................................................... 1
2 Frame structure for peer-to-peer communication........................................................................................... 1
2.1 General.............................................................................................................................................. 1
2.2 Flag sequence.................................................................................................................................... 1
2.3 Address field..................................................................................................................................... 1
2.4 Control field...................................................................................................................................... 2
2.5 Information field............................................................................................................................... 2
2.6 Transparency..................................................................................................................................... 3
2.7 Frame check sequence (FCS) field ................................................................................................... 3
2.8 Format convention............................................................................................................................ 3
2.9 Invalid frames ................................................................................................................................... 5
2.10 Frame abort....................................................................................................................................... 5
3 Elements of procedures and formats of fields for data link layer peer-to-peer communication..................... 5
3.1 General.............................................................................................................................................. 5
3.2 Address field format ......................................................................................................................... 5
3.3 Address field variables...................................................................................................................... 5
3.4 Control field formats......................................................................................................................... 7
3.5 Control field parameters and associated state variables.................................................................... 8
3.6 Frame types....................................................................................................................................... 10
4 Elements for layer-to-layer communication ................................................................................................... 13
4.1 General.............................................................................................................................................. 13
4.2 Primitive procedures......................................................................................................................... 18
4.3 Block interaction diagram of the data link layer............................................................................... 18
5 Definition of the peer-to-peer procedures of the data link layer..................................................................... 22
5.1 Procedure for the use of the P/F bit................................................................................................... 22
5.2 Procedures for unacknowledged information transfer ...................................................................... 22
5.3 Terminal endpoint identifier (TEI) management procedures............................................................ 23
5.4 Initialization of data link layer parameters........................................................................................ 32
5.5 Procedures for establishment and release of multiple frame operation............................................. 33
5.6 Procedures for information transfer in multiple frame operation...................................................... 36
5.7 Re-establishment of multiple frame operation.................................................................................. 40
5.8 Exception condition reporting and recovery..................................................................................... 41
5.9 List of system parameters ................................................................................................................. 43
5.10 Data link layer monitor function....................................................................................................... 44
Annex A – Provision of point-to-point signalling connections ........................................................................... 46
Annex B – SDL for point-to-point procedures ............................................................................................... 47
B.1 General.............................................................................................................................................. 47
B.2 An overview of the states of the point-to-point data link layer entity............................................... 47
B.3 Cover notes ....................................................................................................................................... 50
B.4 The use of queues ............................................................................................................................. 51
B.5 SDL representation ........................................................................................................................... 51
Annex C – SDL representation of the broadcast procedures ............................................................................ 85
Annex D – State transition table of the point-to-point procedures of the data link layer .......................................... 86
D.2 Key to the state transition table......................................................................................................... 86
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2010-11-28
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zouwanli2011-10-10lapd是Q921
