OSI/AS and OSI/TS Supplement (Includes RFC-1006 Support)

CR-TPDU
TPDUs Used by RFC-1006
107751 Tandem Computers Incorporated 5–7
Variable Part
The Variable part is used to define less frequently used parameters. Each
defined parameter contains three fields:
Parameter Code
Parameter Length Indicator
Parameter Value
Information about the following three parameters can be included:
Transport Service Access Point Identifier (TSAP-ID)
TPDU Size
Additional Option Selection - this field is always included in the CR-TPDU
Figure 5-4 illustrates the Variable Part field of the CR-TPDU.
Figure 5-4. Variable Part of the CR-TPDU
065
Octets
• • •
•
•
•
Parameter
Code
Parameter
Length
Indicator
Parameter
Value
n + 1
n + 2 n + 3
8
1
Parameter
Code
Parameter
Length
Indicator
Parameter
Value
n + 4
n + 5 n + 6
Bits
Parameter
Code
Parameter Code
This field can contain either the TSAP-ID, the TPDU Size, or the Additional
Option Selection:
TSAP-ID
When identifying the TSAP-ID (the configured SCF TSEL ENTRY object),
the value of 1100 0001 identifies the calling TSAP and the value of 1100
0010 identifies the called TSAP.
TPDU Size
When identifying the TPDU Size, defines the proposed maximum TPDU
size (in octets, including TPDU header and user data, but excluding the
transport packet header) to use over the requested transport connection.
The value is 1100 0000.