Visara FEP-4600 Planning Guide - Manual (Page 24)

Chapter 2. Support of PU 2.0 Platforms
2-6 707117-003
XCA Gateway Operation
Setting up an XCA (External Communication Adapter) gateway takes a different
approach that is much more advantageous for LAN attached PUs. Introduced with the
IBM 3172, a single subchannel is associated with a network adapter on the FEP-4600. If
multiple network adapters are to be used for the XCA function, then at least one
subchannel for each network adapter is required. Up to 255 downstream PUs and all of
their associated sessions can connect through each network adapter. Note that for
performance reasons, you may choose to limit the number of downstream PUs through a
single adapter to a smaller number than you can actually configure.
IBM z990
Director
Appears to the host as if the channel where
directly attached to a LAN (Token Ring or
Ethernet)