Overview of IBM Networking
CMCC Adapter Features for TCP/IP Environments
IP Host Backup
You can connect multiple mainframes to a single CMCC adapter using an ESCON director. Often, these mainframes run using the ESCON Multiple Image Facility (EMIF), which permits the physical machine to be divided into multiple logical partitions (LPARs). By defining an unused partition on another mainframe, a user can move the operating system from a failed mainframe or mainframe partition to the unused partition. By having multiple paths to each device, the move is accomplished without changing the mainframe software. This function also permits moving an IP stack between multiple operating system images.
On the CMCC adapter, each IP connection is treated as a physical device. The CMCC adapter does not support multiple active paths to a single IP connection (or device). Prior to IP Host Backup, the router configuration had to be changed whenever the mainframe operating system was moved from one mainframe or LPAR to another. The IP Host Backup feature permits the mainframe operating system to be moved from one mainframe to another without requiring a change to the router configuration at the time of the move.
Note IP Host Backup does not provide single system image or automatic failover to a waiting backup application. Host operator action on the mainframe is required in these instances.
For more information about configuring a CMCC adapter for IP host backup, see the “Configuring CLAW and TCP/IP Offload Support” chapter in this publication.
Cisco Multipath Channel+
CMPC+ is the Cisco implementation of IBM’s MPC+ feature. The CMPC+ feature supports the MPC+ features and protocols necessary to support IP. CMPC+ enables High Performance Data Transfer (HPDT). It allows TCP/IP connections to the host through CMCC adapters, using either the TCP/IP stack or the High Speed Access Services (HSAS) IP stack.
CMPC+ offers the following support:
•Support for TCP/IP and HSAS Transmission Group (TG)
•Support for one IP stack per MPC+ group
•Support for one read subchannel and one write subchannel per CMPC+ group. The read subchannel and write subchannel in an MPC+ group can be on different physical channels.
•Support for up to 64 KB per I/O block
•Runs on the CIP and the CPA
Up to 64 MPC+ groups can be configured on a CMCC, depending on memory configuration.
The CMPC+ feature can coexist with the CLAW, TCP/IP Offload, CSNA, CMPC, and TN3270 server features on the same CMCC adapter.
For details about configuring a CMCC adapter for CMPC+, see the “Configuring CMPC+” chapter in this publication.
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