39
Primary to Basic Rate ISDN Multiplexer
TECHNICAL: 0118 931 2233
Information Provided at Layer 2
A typical display of a short ASCII layer 2 message is shown below.
23: TA Ch BRI 2 L2
00:01:75:30.271
SAPI= 0, TEI= 40, C/R= 0, P/F=1, TYPE= SABME
The information presented is outlined below.
(a) Sequence Number
Each message has a unique number so that old messages can be easily located.
(b) Originator
This field reports which side generated the message. For PRI 1 the text is MUX for ISDN
Multiplexer (The Primary to Basic Rate ISDN Multiplexer) generated messages and NET for
messages generated by the network (exchange or switch). On the other ports, the text is TA
for terminal generated messages and MUX for messages generated by the ISDN Multiplexer
(The Primary to Basic Rate ISDN Multiplexer).
(c) Channel Number
The channel number (e.g. BRI 1) on which the event occurred.
(d) Layer Number
The layer on which the event is being reported.
(e) Timestamp
The time that the message was generated (NT message) or received (TE message). The
timestamp has the form dd:hh:mm:ss.nnn where dd represents days, hh hours, mm minutes,
ss seconds and nnn milliseconds.
(f) Service Access Point Identifier*
(g) Terminal Endpoint Identifier*
(h) Command/Response Bit*
(i) Poll/Final Bit*
(j) Type*
The message type, being one off I, RR, RNR, REJ, SABME, DM, UI, DISC, UA, FRMR,
XID.
