Parallel transmission groups

A transmission group consist of one or more physical links connecting two subareas. In a VTAM-to-VTAM configuration, each transmission group is single-link-capable only. Although you can have as many as 255 transmission groups, only 16 of these can be defined between two adjacent VTAMs, because the maximum number of explicit routes that can be defined is 16.

For more information about parallel transmission groups, see the z/OS Communications Server: SNA Network Implementation Guide.

Figure 1 shows parallel transmission groups TGN2 and TGN3 in a multiple-domain network.

Figure 1. Parallel transmission groups in a multiple-domain network. Host A17 is an interchange node (ICN). Host A500 is a migration data host (MDH).

A diagram that shows a parallel transmission group in a multiple-domain network. The group consists of an interchange node (ICN) A17 and a migration area data host (MDH) A500.

The first channel-attachment major node that follows represents the view of the connection from host A17 in Figure 1.

The VBUILD definition statement defines the beginning of this channel-attachment major node (TYPE=CA).

The GROUP definition statement indicates that the attachments between hosts A17 and A500 are channel-to-channel attachments (LNCTL=CTCA).

You must code one LINE definition statement for each channel adapter. The address specified by the ADDRESS operand is a 3- or 4-digit hexadecimal device address, which must match the value assigned to the device during operating system I/O definition. With 4-digit device addressing, you can specify as many as 65536 channel-attached devices.

You must code one PU definition statement for each LINE definition statement. The TGN operands specify transmission group numbers for the channel link transmission groups (TGN=2, TGN=3).

*  =====> BEGINNING OF DATA SET A17CTC2
***********************************************************************
* A17CTC2  - VTAM CHANNEL-ATTACHMENT MAJOR NODE (CTCA) - ICN A17      *
*          - CONNECTS A17 TO A500                                     *
***********************************************************************
         VBUILD TYPE=CA           ** CTCA MAJOR NODE                **
CTCGRP2  GROUP DELAY=.001,        ** LOW-PRIORITY DATA TRANS DELAY  ** X
               LNCTL=CTCA,        ** CTCA LINKS                     ** X
               ISTATUS=ACTIVE,    ** INITIAL ACTIVATION STATE       ** X
               MAXBFRU=10,        ** RECEIVE DATA BUFFER PAGE SIZE  ** X
               MIH=YES,           ** MISSING INTERRUPT HANDLING     ** X
               REPLYTO=3.0        ** CHANNEL PROG COMPLETE TIME OUT **
***********************************************************************
* CTC CONNECTION FROM A17 TO A500                                     *
***********************************************************************
CTCLINE4 LINE  ADDRESS=0BC4       ** CHANNEL UNIT ADDRESS           **
CTCPU4   PU    PUTYPE=4,          ** PHYSICAL UNIT TYPE             ** X
               TGN=2              ** TRANSMISSION GROUP NUMBER      **
***********************************************************************
* CTC CONNECTION FROM A17 TO A500                                     *
***********************************************************************
CTCLINE5 LINE  ADDRESS=0BC5       ** CHANNEL UNIT ADDRESS           **
CTCPU5   PU    PUTYPE=4,          ** PHYSICAL UNIT TYPE             ** X
               TGN=3              ** TRANSMISSION GROUP NUMBER      **
*  =====> END OF DATA SET A17CTC2

The next channel-attachment major node that follows represents the view of the connection from host A500 in Figure 1.

The VBUILD definition statement defines the beginning of this channel-attachment major node (TYPE=CA).

The GROUP definition statement indicates that the attachments between hosts A17 and A500 are channel-to-channel attachments (LNCTL=CTCA).

You must code one LINE definition statement for each channel adapter.

You must code one PU definition statement for each LINE definition statement. The TGN operands specify transmission group numbers for the channel link transmission groups (TGN=2, TGN=3).

*  =====> BEGINNING OF DATA SET A50CTC2
***********************************************************************
* A50CTC2  - VTAM CHANNEL-ATTACHMENT MAJOR NODE (CTCA) - MDH A500     *
*            CONNECTS SA 500 TO SA 17 -                               *
***********************************************************************
         VBUILD TYPE=CA           ** CTCA MAJOR NODE                **
CTCGRP2  GROUP DELAY=.001,        ** LOW-PRIORITY DATA TRANS DELAY  ** X
               LNCTL=CTCA,        ** CTCA LINKS                     ** X
               ISTATUS=ACTIVE,    ** INITIAL ACTIVATION STATE       ** X
               MAXBFRU=10,        ** RECEIVE DATA BUFFER PAGE SIZE  ** X
               MIH=YES,           ** MISSING INTERRUPT HANDLING     ** X
               REPLYTO=3.0        ** CHANNEL PROG COMPLETE TIME OUT **
***********************************************************************
* CTC CONNECTION FROM A500 TO A17                                     *
***********************************************************************
CTCLINE4 LINE  ADDRESS=BC4        ** CHANNEL UNIT ADDRESS           **
CTCPU4   PU    PUTYPE=4,          ** PHYSICAL UNIT TYPE             ** X
               TGN=2              ** TRANSMISSION GROUP NUMBER      **
***********************************************************************
* CTC CONNECTION FROM A500 TO A17                                     *
***********************************************************************
CTCLINE5 LINE  ADDRESS=BC5        ** CHANNEL UNIT ADDRESS           **
CTCPU5   PU    PUTYPE=4,          ** PHYSICAL UNIT TYPE             ** X
               TGN=3              ** TRANSMISSION GROUP NUMBER      **
*  =====> END OF DATA SET A50CTC2