Step 3: Prepare your VTAM definitions

There are four categories of definitions you need for your APPN-enabled VTAM®:

Start options
EE XCA major node
Switched major node definitions
Model major node definitions

Start options:

EEVERIFY
The default value for this option is ACTIVATE, which is the recommended value for EE networks. See z/OS Communications Server: SNA Resource Definition Reference for information about the EEVERIFY start option.
HPRARB
The default value for this option is RESPMODE, which is the recommended value for EE networks. See z/OS Communications Server: SNA Resource Definition Reference for information about the HPRARB start option.
HPRPSDLY
Use this start option to specify the minimum amount of time that VTAM delays before an RTP pipe (that has an unresponsive partner) enters a path switch state. See z/OS Communications Server: SNA Resource Definition Reference for information about the HPRPSDLY start option.
HPRPSMSG
Indicates whether VTAM should limit the number of HPR path switch messages that are issued in the event of a network outage. See z/OS Communications Server: SNA Resource Definition Reference for information about the HPRPSMSG start option.
HPRPST
The maximum time that VTAM tries a path switch before ending a connection. See z/OS Communications Server: SNA Resource Definition Reference for information about the HPRPST start option.
HPRSESLM
Specifies whether VTAM should limit the number of sessions assigned to each RTP connection. See z/OS Communications Server: SNA Resource Definition Reference for information about the HPRSESLM start option.
HPRSTALL
Use this start option to set the amount of time an RTP pipe may remain continuously stalled before being stopped automatically. See z/OS Communications Server: SNA Resource Definition Reference for information about the HPRSTALL start option.
IPADDR/HOSTNAME
Use one of these options to specify a local static VIPA address that other EE endpoints will use to communicate with this VTAM. The decision whether to use IPADDR or HOSTNAME should be based on what you decided in the previous section, Step 2: Evaluate IP address resolution.
MULTPATH
Use this start option to disable IP multipath routing support for IPv4 and IPv6 Enterprise Extender connections. For more information about the MULTPATH start option, see z/OS Communications Server: SNA Resource Definition Reference. For more information about the IP multipath routing, see z/OS Communications Server: IP Configuration Guide.
PMTUD
Use this start option to disable path MTU discovery for IPv4 and IPv6 Enterprise Extender connections. See z/OS Communications Server: SNA Resource Definition Reference for information about the PMTUD start option.
TCPNAME
See TCPNAME in z/OS Communications Server: SNA Resource Definition Reference for more information.

Tip: Although specifying TCPNAME is optional, you should specify a name for the TCP/IP stack that defines the local static VIPA for EE because it causes more reliable line activation. See z/OS Communications Server: SNA Resource Definition Reference for information about the TCPNAME start option.

Restriction: All local Enterprise Extender static VIPA addresses must be associated with a single TCP/IP stack. Even in common-INET environments, EE always establishes affinity with only one TCP/IP stack.
T1BUF/T2BUF
These are two buffer pool start options designed to optimize data transmission for Enterprise Extender configurations that use QDIO/iQDIO device drivers. See z/OS Communications Server: SNA Resource Definition Reference for information about the T1BUF/T2BUF start options. Find out how tuning these options can benefit EE performance in Tuning the EE network.
UNRCHTIM
Specifies the options associated with Enterprise Extender connection network reachability awareness. See z/OS Communications Server: SNA Resource Definition Reference for information about the UNRCHTIM start option.

EE XCA major node:

Activation of the EE XCA major node enables the use of EE, and establishes the following relationships.

The PORT definition represents a relationship between VTAM and TCP/IP for sending and receiving EE packets.
Each GROUP entry is composed of a set of LINE definitions sharing the same characteristics, such as IP address or host name. For groups that define a connection network, the APPN TG characteristics such as CAPACITY and SECURITY are defined on the GROUP statement in the XCA major node. The EEVERIFY operand on the GROUP statement overrides the EEVERIFY start option value. See z/OS Communications Server: SNA Resource Definition Reference for information about the EEVERIFY operand under XCA major node for EE.
Guideline: Ensure that the CAPACITY specified is a value representing the effective capacity of the end-to-end IP connectivity. Note that this might be a different capacity than the TCP/IP interface.
Each LINE definition represents a potential switched connection with a partner EE endpoint.

These relationships enable VTAM and TCP/IP to communicate across a connection that is associated with both the remote and local IP addresses. This communication begins when the first line, associated with a unique IP address, is activated.

The XCA major node defines the IP port with the following statements, operands and functions:

The PORT statement identifies the name of a port through which an HPR connection through the IP network is made. The PORT statement must be set to MEDIUM=HPRIP for EE.
The IPPORT operand on the PORT statement specifies the first of five consecutive UDP ports intended for all EE communication from this host.
Requirements:
- The IPTOS operand on the PORT statement specifies values for the type of service bytes for each of the five UDP ports defined for EE. These IP precedence values within the ToS byte must be consistent throughout the network. By coding or defaulting the IPTOS operand, you preserve SNA transmission priority through the IP type of service byte that is recognized by IP networking hardware. Further customization of the ToS byte can be done through the z/OS® IP policy agent. See the sections on IPTOS, XCA major node, Customizing IP type of service, and QoS preservation dependency in z/OS Communications Server: SNA Resource Definition Reference for more information.
- Use the default value of 12000 when specifying IPPORT.
The LIVTIME, SRQTIME, and SRQRETRY logical data link control (LDLC) parameters are specified on the PORT or GROUP statement. More information about these parameters is in z/OS Communications Server: SNA Resource Definition Reference.
The GROUP statement must be set to DIAL=YES to define a TG. Optionally, the GROUP statement can specify the source VIPA address explicitly or implicitly, using a host name value to be resolved into the address. If the IP address or host name is not defined on the XCA major node, the IP address or host name defined using VTAM start options is used as the source VIPA address. You must define separate GROUPs for IPv4 and IPv6 EE connections.

Guideline: Define at least as many lines as the maximum number of concurrent EE connections that are expected. Specifying DYNPU=YES on the GROUP statement indicates lines within the group that are eligible for dynamic PU assignments for inbound connections. This eliminates the need for explicit switched PU definitions for those connections. You can customize dynamic PUs for EE by defining a DYNTYPE=EE entry in a model major node. See Model major node definition for more information.

Requirements:

For EE COS preservation, IP WAN devices must be enabled for QoS.
All EE definitions must be coded within a single XCA major node.

Following is a sample XCA major node definition for Enterprise Extender:

**************************************************************
*
* NAME: XCA1A   XCA MAJOR NODE FOR HOST 1A Enterprise Extender
*
**************************************************************
XCA1A    VBUILD  TYPE=XCA
PORT1A   PORT   MEDIUM=HPRIP,IPPORT=12000,
                IPTOS=(20,40,80,C0,C0),LIVTIME=(10,30),
                SRQTIME=15,SRQRETRY=3
*
GP1A2A   GROUP  DIAL=YES,ANSWER=ON,ISTATUS=INACTIVE,
                CALL=INOUT,
                EEVERIFY=60,
                IPADDR=9.1.1.1,LIVTIME(15,40),SRQTIME=20,SRQRETRY=5

LN1A2A   LINE
P1A2A    PU
*
GP1A2A1  GROUP  DIAL=YES,ANSWER=ON,ISTATUS=INACTIVE,
                CALL=IN,DYNPU=YES,EEVERIFY=NEVER,
                IPADDR=9.1.1.2
LN1A2A2  LINE
P1A2A2   PU
*
* HOSTNAME resolves to IPv6 address
GP1A2A2  GROUP  DIAL=YES,ANSWER=ON,ISTATUS=INACTIVE,CALL=INOUT,
                HOSTNAME=HOST.DOMAIN.COM
LN1A2A2  LINE
P1A2A2   PU
*
* IPv6 address
GP1A2A3  GROUP  DIAL=YES,ANSWER=ON,ISTATUS=INACTIVE,CALL=INOUT,
                IPADDR=2001:0DB8::93:1:1:1
LN1A2A3  LINE
P1A2A3   PU

Switched major node definition:

The switched major node defines the Enterprise Extender switched TGs with the following statements:

The PU statement defines the remote node
The PATH statement defines the remote IPv4 address, or a host name that can be resolved into an IPv4 or an IPv6 address.

The PU definitions can be used for dialing outbound and for identifying PUs for incoming calls to this host. See the section on switched major node definitions in z/OS Communications Server: SNA Resource Definition Reference for more information.

Dial guidelines: For predefined EE connections:

Coding a PATH definition statement with GRPNM enables an incoming call to prefer one switched PU over another. When the GROUP name that is associated with the line selected for the inbound call matches the GRPNM on the switched PATH, the switched PU associated with the PATH is preferred over another switched PU that does not match, or does not have a PATH definition statement coded.
Specify APPN TG characteristics on the switched PU used for dial-out connections or on the DYNTYPE=EE model PU for dynamically defined dial-in connections.
Specify the EEVERIFY operand on the switched PU used for dial-out connections or on the DYNTYPE=EE model PU for dynamically defined dial-in connections to override the EEVERIFY start option value. See z/OS Communications Server: SNA Resource Definition Reference for information about the EEVERIFY operand in the Switched major node or Model Major node sections, under the DYNTYPE=EE description.

Following is a sample switched major node definition for Enterprise Extender:

**************************************************************
*
*  NAME: SWXCA1A   SWITCHED MAJOR NODE FOR HOST 1A
*
**************************************************************
SWXCA1A  VBUILD  TYPE=SWNET,MAXNO=256,MAXGRP=256
*
SW1A2A   PU     IDBLK=003,IDNUM=00003,ADDR=01,
                CPNAME=SSCP2A,EEVERIFY=60,
                CPCP=YES,HPR=YES,
                PUTYPE=2,TGP=GIGENET
PATH2A   PATH   IPADDR=93.1.1.1,
                GRPNM=GP1A2A
*
* HOSTNAME resolves to IPv4 address
SW1A2A1  PU     IDBLK=004,IDNUM=00004,ADDR=02,
                CPNAME=SSCP2A,
                CPCP=YES,HPR=YES,
                PUTYPE=2,TGP=GIGENET
PATH2A1  PATH   HOSTNAME=SSCP2A,
                GRPNM=GP1A2A1
*
* HOSTNAME resolves to IPv6 address
SW1A2A2  PU     IDBLK=005,IDNUM=00005,ADDR=03,
                CPNAME=SSCP2A,
                CPCP=YES,HPR=YES,
                PUTYPE=2,TGP=GIGENET
PATH2A2  PATH   HOSTNAME=SSCP2AV6,
                GRPNM=GP1A2A2     
*
* IPv6 address
SW1A2A3  PU     IDBLK=006,IDNUM=00006,ADDR=04,
                CPNAME=SSCP2A,
                CPCP=YES,HPR=YES,
                PUTYPE=2,TGP=GIGENET
PATH2A3  PATH   IPADDR=2001:0DB8::91:1:1:1,
                GRPNM=GP1A2A3

Model major node definition:

To define the TG characteristics of a dynamic PU for EE, code a model EE PU within the model major node. This PU model definition is used only if all of the following are true:

DYNPU=YES is explicitly coded on a GROUP statement under an EE PORT within an XCA major node
A LINE statement coded under that GROUP statement is eligible to accept incoming calls (CALL=IN or CALL=INOUT, and ANSWER=ON are coded, sifted down from the GROUP statement, or taken as defaults)
Tip: Using CALL=INOUT provides the most flexibility.
A predefined switched PU in connectable state that matches the partner cannot be found at dial-in time

Tip: Using the model PU enables you to specify things such as non-default TG characteristics and an installation-specific DISCNT value without having to code a PU statement for each remote node that can dial in. Also, by using the DWINOP, REDIAL, and REDDELAY parameters, you can specify whether you want VTAM to attempt to reconnect to the partner when the connection becomes inoperative. You can also specify up to four predefined TG numbers in the order you prefer for your EE connections. Include ANY as one of the four if you want to have the EE connection established even if your preferred TG numbers are not available. ANY can be placed anywhere in the list.

The EEVERIFY operand on the PU statement overrides the EEVERIFY start option value.

Following is a sample model major node definition that defines a model PU to be used for dynamically created, non-connection-network EE PUs for inbound connections.

**************************************************************
*
*  NAME: MODELA1A   MODEL MAJOR NODE FOR HOST 1A
*
**************************************************************
MODELA1A VBUILD  TYPE=MODEL
*
EEMODEL  PU     DYNTYPE=EE,
                CAPACITY=100M,
                COSTTIME=0,
                CPCP=YES,
                EEVERIFY=60,
                DISCNT=NO,
                DWINOP=YES,
                REDIAL=30,
                REDDELAY=60,
                TGN=(11,8,15,ANY)