External communication adapter (XCA) major node

This topic describes sample external communication adapter major node definitions.

Local area networks can connect to VTAM® through an external communication adapter (XCA), such as an IBM® 3172 Nways Interconnect Controller or an IBM S/390® Open Systems Adapter. VTAM and an XCA support the following types of local area networks:
  • Carrier sense multiple access with collision detection (CSMA/CD) 802.3
  • Token ring IEEE 802.5
  • Fiber Distributed Data Interface (FDDI)
  • Token-bus

ATM networks operating in LAN emulation mode appear to VTAM to be CSMA/CD 802.3 LANs or token-ring networks and are defined to VTAM as such. ATM networks operating in native mode are defined differently.

An external communication adapter major node is defined for each LAN connected to the XCA. The major node is defined with a VBUILD TYPE=XCA definition statement. For each LAN connected through an XCA, code a VBUILD TYPE=XCA definition statement. The line groups, lines, and physical units attached to the port are minor nodes defined by GROUP, LINE, and PU definition statements. You can also specify the DIALNO operand on the PATH definition statement for a 3172 switched data network.

Three types of support are defined through the external communication adapter major node:
  • Peripheral: attach VTAM to peripheral nodes connected to LAN
  • Subarea: attach VTAM to subarea nodes connected to LAN
  • APPN: APPN-to-APPN over an IBM 3172 Nways Interconnect Controller