1 Scope
2
References
3
Definitions
3.1 Reference model definitions
3.2 Service conventions definitions
3.3 Network service definitions
3.4 X.25 definitions
3.5 APS definitions
4
Abbreviations
4.1 Reference model abbreviations
4.2 Network layer abbreviations
4.3 X.25 abbreviations
4.4 Data link layer abbreviations
4.5 Other abbreviations
5
Overview
5.1 Configurations
5.2 Modes of operation and their APS layers representation
5.2.1 V.42-dependent mode
5.2.2 LAPB mode
5.2.3 X.25 mode
5.2.4 Mode negotiations
5.2.5 Mode support
6
Provision of the OSI CONS
6.1 Control of underlying connections
6.2 Mapping OSI CONS to/from X.25 PLP
6.3 Mapping OSI CONS to/from the APS network protocol
7
APS layer 2 protocols
7.1 Introduction
7.2 Start/stop LAPB
7.3 APS data link protocol
7.3.1 Reception of incorrect frames
7.4 Transparency
7.5 APS layer 2 operation and establishment of the underlying
connection
7.5.1 Point-to-Point configuration
7.5.1.1 Establishment of the
underlying connection
7.5.1.2 Data link set-up
7.5.1.3 LAPB addressing
7.5.1.4 Time fill
7.5.2 PAD configuration
7.5.2.1 Establishment of the
underlying connection
7.5.2.2 Data link set-up
7.5.2.3 LAPB addressing
7.5.2.4 Time fill
7.5.2.5 Mapping of APS layer
2 frames to packets
7.5.2.6 Exception conditions
7.5.3 Direct network configuration
7.5.3.1 Establishment of the
underlying connection
7.5.3.2 LAPB data link set-up
7.5.3.3
LAPB addressing
7.5.3.4 Time fill
8
APS layer 3 protocols
8.1 The APS network protocol
8.1.1 APS network protocol elements of
procedure
8.1.1.1
Connection establishment procedure
8.1.1.2 Data transfer
procedure
8.1.1.3 Disconnect procedure
8.1.2 APS network protocol structure
8.1.2.1 The connect request PDU
8.1.2.2 The connect confirm
PDU
8.1.2.3 The data transfer PDU
8.1.2.4 The disconnect request
PDU
8.1.2.5 The disconnect
confirm PDU
8.1.2.6 Maximum user data in
APS NPDUs
8.2 X.25 PLP operation
8.2.1 Optional and negotiable parameters
8.2.1.1 Parameter usage in the Direct Network configuration
Annex A – Transparency
A.0 Transparency
A.1 Introduction
A.2 APS PAD transparency
Annex B – APS protocols selection string
B.0 APS protocols
selection string
B.1 Introduction
B.2 APS protocols selection string format
B.3 Use of the call user data in X.25 call requests
Annex C – Use of the APS network protocol to provide the OSI Connection-mode
network service
C.0 Use of the APS network protocol to provide the OSI
connection-mode network service
C.1 Introduction
C.2 Network connection establishment phase
C.3 Data transfer phase
C.3.1 Handling of
NS-user-data
C.3.2 The reset service
C.4 Network connection release phase
C.4.1 Mapping of N-DISCONNECT Parameters
Annex D – Recommended practices for use in MHS environment
D.0 Recommended practices
D.1 APS layer 3 protocols
D.1.1 Use of the APS network protocol for
simultaneous communications
D.1.2 Handling of future versions
D.2 APS layer 2 protocols
D.2.1 LAPB retransmission timer
D.3 Start/stop framing
D.3.1 Fast Frame Control Check (FCS)
implementation
D.4 Modems
D.4.1 V.42 modems
D.4.2 Modems with automatic data rate switching
D.4.3 Modem flow control
D.5 PAD operation
D.5.1 Recommended PAD parameters
D.5.2 Remote PAD parameters
D.6 Timers and counters
D.6.1 APS layer 2
D.6.2 APS layer 3