Qualified ports

In some cases all clients need to use the same port number, but the Telnet parameters need to be differentiated by destination IP address or destination linkname. The destination IP address can be either an IPv4 or IPv6 IP address.

For example, two TN3270E Telnet servers are going to be merged into one server. Currently, server 1 is bound to IP address 1.1.1.1 and is running with a set of definitions for port 23. Server 2 is bound to IP address 2.2.2.2 and is running with a different set of definitions for port 23. Before the servers are merged into one, users connect to either 1.1.1.1,port 23 or 2.2.2.2,port 23, depending on which Telnet services the users want. The sample definition statements are:

Server 1

 TelnetParms
  Port 23
  Inactive 600      ; Drop after 10 minutes of no activity
 EndTelnetParms

 BeginVTAM
  Port 23
  DefaultLus TCPABC01..TCPABC49 EndDefaultLus
  DefaultAppl TSO
 EndVTAM

Server 2

 TelnetParms
  Port 23
  Inactive 0        ; Never drop
 EndTelnetParms

 BeginVTAM
  Port 23
  DefaultLus TCPABC50..TCPABC99 EndDefaultLus
  DefaultAppl CICS
 EndVTAM

After the servers are merged, both home addresses are supported by a single server. One way to keep the Telnet definitions separate is to change the port number in one of the definition sets. For instance, the port 23 definitions associated with the old server 2 could be changed to be port 2023. The end result is one TN3270E Telnet server with port 23 and port 2023, where port 23 has the definitions used in the old server 1 and port 2023 has the definitions used in the old server 2. The definitions are still separate. However, all the users who were connecting to 2.2.2.2 port 23 now have to change their clients to port 2023. The sample definition statements are changed as follows:

Merged Server

 TelnetParms
  Port 23
  Inactive 600      ; Drop after 10 minutes of no activity
 EndTelnetParms

 BeginVTAM
  Port 23
  DefaultLus TCPABC01..TCPABC49 EndDefaultLus
  DefaultAppl TSO
 EndVTAM

 TelnetParms
  Port 2023
  Inactive 0        ; Never drop
 EndTelnetParms

 BeginVTAM
  Port 2023
  DefaultLus TCPABC50..TCPABC99 EndDefaultLus
  DefaultAppl CICS
 EndVTAM

With port qualification, the system administrator can qualify the port number with the destination IP address or linkname to keep the Telnet services separate. In this case, the destination IP address is used. The qualified port allows the users of either old stack to connect without making any changes to their client. The sample definition statements would be changed to:

Merged Server

 TelnetParms
  Port 23,1.1.1.1
  Inactive 600      ; Drop after 10 minutes of no activity
 EndTelnetParms

 BeginVTAM
  Port 23,1.1.1.1
  DefaultLus TCPABC01..TCPABC49 EndDefaultLus
  DefaultAppl TSO
 EndVTAM

 TelnetParms
  Port 23,2.2.2.2
  Inactive 0        ; Never drop
 EndTelnetParms

 BeginVTAM
  Port 23,2.2.2.2
  DefaultLus TCPABC50..TCPABC99 EndDefaultLus
  DefaultAppl CICS
 EndVTAM

You cannot QUIESCE, RESUME, or STOP a qualified portion of a port. If the port has several qualified port profiles, the VARY TCPIP,tnproc,QUIESCE, the VARY TCPIP,tnproc,RESUME, and the VARY TCPIP,tnproc,STOP commands affect all qualified port profiles associated with the port being quiesced, resumed, or stopped. In the example above, V TCPIP,tnproc,T,STOP,PORT=23 will stop port 23,1.1.1.1 and port 23,2.2.2.2. It is not possible to stop port 23,1.1.1.1 or port 23,2.2.2.2 individually. All display commands that allow port specification allow you to specify a qualified port. If just the port number is specified, only the unqualified port, if it exists, is displayed. The qualified port profiles are not displayed. DBCSTRANSFORM can be active on only one port, but can be active on one, some, or all of the qualified profiles of that port.