Redundant I/O Interconnect For I/O Drawer - IBM z13s Technical Manual

A conceptual view of how redundant I/O interconnect is accomplished is shown in
Figure 2-25.
Figure 2-25 Redundant I/O interconnect for I/O drawer
Normally, the HCA2-C fanout in a CPC drawer connects to the IFB-MP (A) card and services
domain A in an I/O drawer. In the same fashion, a second HCA2-C fanout of a CPC drawer
connects to the IFB-MP (B) card and services domain B in an I/O drawer. If the connection
from the CPC drawer IFB-MP (A) to the I/O drawer is removed, connectivity to domain B is
maintained. The I/O is guided to domain B through the interconnect between IFB-MP (A) and
IFB-MP (B).
Note: Both IFB-MP cards must be installed in the I/O Drawer to maintain the interconnect
across I/O domains. If one of the IFB-MP cards is removed, then the I/O cards in that
domain (up to four) become unavailable.
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IBM z13s Technical Guide
HCA2-C