IBM BC-203 manual CMCC Adapter Features for SNA Environments, Cisco SNA, BC-250

Overview of IBM Networking

CMCC Adapter Features for SNA Environments

CMCC Adapter Features for SNA Environments

The Cisco IOS software supports the following features for CMCC adapters in SNA environments:

•Cisco SNA, page 250

•Cisco Multipath Channel, page 251

•TN3270 Server, page 251

Cisco SNA

The CSNA feature provides support for SNA protocols to the IBM mainframe from Cisco 7500, Cisco 7200, and Cisco 7000 with RSP7000 series routers, using CMCC adapters (over both ESCON and parallel interfaces). As an IBM 3172 replacement, a CMCC adapter in a Cisco router supports the External Communications Adapter (XCA) feature of the Virtual Telecommunications Access Method (VTAM).

Support for the XCA feature allows VTAM to define the CMCC’s Token Ring devices as switched devices. XCA support also allows the CMCC adapter to provide an alternative to FEPs at sites where the NCP is not required for SNA routing functions.

The CSNA feature supports communication between a channel-attached mainframe and the following types of devices attached to a LAN or WAN:

•PU 2.0 SNA node

•PU 2.1 SNA node

•PU 5/4 SNA node

CSNA also supports communication between two mainframes running VTAM that are either channel-attached to the same CMCC adapter card, or channel-attached to different CMCC adapter cards.

The CSNA feature provides SNA connectivity through a MAC address that is defined on an internal adapter in a CMCC. The internal adapter is a virtual adapter that emulates the LAN adapter in an IBM 3172 Interconnect Controller. Each internal adapter is defined in a corresponding XCA major node in VTAM, which provides an access point (LAN gateway) to VTAM for SNA network nodes.

The internal adapter is configured on an internal (virtual) Token Ring LAN located in the CMCC. Each CMCC can be configured with multiple internal Token Ring LANs and internal adapters. Each internal Token Ring LAN must be configured to participate in source-route bridging to communicate with the LAN devices attached to the router.

By providing Cisco Link Services (CLS) and the LLC2 protocol stack on the CMCC adapter card, all frames destined to or from the CMCC adapter card are switched by the router. The presentation of LAN media types allows the CSNA feature to take advantage of current SRB, RSRB, DLSw+, SR/TLB, internal SDLLC, QLLC services, and APPN functionality through SNASw.

The CSNA feature can coexist with the CLAW, TCP/IP Offload, CMPC, CMPC+, and TN3270 server features on the same CMCC adapter.

For details about configuring a CMCC adapter for CSNA, see the “Configuring CSNA and CMPC” chapter in this publication.

Cisco IOS Bridging and IBM Networking Configuration Guide

BC-250