Implementing an APPN network

An APPN network contains network nodes and end nodes connected by APPN connections. VTAM® can be coded as either a network node or an end node. Configuring VTAM for APPN is optional. To configure VTAM as an APPN node, select the characteristics of the node and define the resources of that node to VTAM.

The HOSTSA, NODETYPE, and SACONNS start options are used to determine what type of node VTAM will be. Table 1 shows how these start options are defined for the different types of nodes.

Table 1. Start options and node type relationship
Node type	NODETYPE	HOSTSA	SACONNS
Subarea node	not coded	subarea number	YES
Interchange node	NN	subarea number	YES
Migration data host	EN	subarea number	YES
Network node	NN	subarea number*	NO
End node	EN	subarea number*	NO
*HOSTSA is optional. If not specified, VTAM will start as a EN or NN. If HOSTSA is specified, then SACONNS=NO must be specified to start VTAM as an EN or NN.

By coding the NODETYPE start option, you specify a node as an APPN node. After NODETYPE is coded, the following start options default to the values needed to enable APPN connections.

CPCP: The CPCP start option defaults to LEASED and enables CP-CP control sessions across APPN leased links. The other possible values for CPCP are SWITCHED, YES (for all links), and NO (for no links). For information about modifying CP-CP session enablement, see Enabling control sessions.
CONNTYPE: The CONNTYPE start option defaults to the value APPN and enables full APPN function across a link. The other connection type value is LEN. There is also a CONNTYPE operand on the PU definition statement that can be used to override the value of the start option for specific links. For more information about the CONNTYPE start option and operand, see Implementing a combined APPN and subarea network.