- Enterasys Security Router User's Guide

Understanding ISDN
XSR User’s Guide 11-7
Rx ISDN-BRI 1/0 03:13:47:676 Q921 UI p 0 sapi 63 tei 127 c/r 1
• + 2nd line:
info:0F 00 00 06 FF
Tx ISDN-BRI 1/0 03:13:52:601 Q921 INFO p 0 nr 0 ns 0 sapi 0 tei 64 c/r0
info:08 00 7B 3A 07 32 38 30 30 35 35 35
Tx ISDN-BRI 1/0 03:13:52:556 Q921 SABME p 1 sapi 0 tei 64 c/r 0
Rx ISDN-BRI 1/0 03:13:52:661 Q921 RR p/f 0 nr 1 sapi 0 tei 64 c/r 0
Reference Parameters
UI - Unnumbered Information.
SABME - Set Asynchronous Balanced Mode Extender.
c/r - Command/Response field bit.
SAPI - Service Access Point Identifier.
TEI - Terminal Endpoint Identifier.
Ua - Unnumbered acknowledgement.
nr - Receive Sequence Number.
ns - Send Sequence Number.
INFO - Q931 Information message.
RR - Receive Ready
Q931 Decoding
At Q931 Layer 3, the XSR partially decodes Q931 messages as follows:
• On line 1 after the time stamp field, the call reference and message type displays.
• On line 2, the complete hexadecimal dump of the message is shown.
• On the following lines the IEs, if any, display as follows:
– Hexadecimal code of the IE
–Name of the IE
– Hexadecimal dump of the IE or further decoding
Refer to the following Q931 example:
–
+ 1st line:
Tx ISDN-BRI 1/0 03:32:48:203 CallRef=7 SETUP
– + 2nd line:
00 81 12 0E 08 01 07 05 04 02 88 90 18 01 81 6C 06 00
80 32 38 30 30 70 05 80 32 35 30 30
Note: For a complete list of reference codes, see: http://www.atis.org/tg2k/