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Configuring Passthrough Services
Configuring PU Concentration
Configuring PU Concentration
Normally, a dependent LU session requires a direct communications link
to the host computer. However, a node running SNAplus2 that has a
direct communications link to the host can also provide PU concentration
facilities to LUs on downstream computers, enabling them to access the
host over the communications link from the SNAplus2 node. The
downstream computer must contain an SNA PU type 2.0 or 2.1 to
support dependent communication with the host. For example, the
downstream computer could be another computer running SNAplus2 in
a standalone configuration.
Using the PU concentration feature, all the data transferred between the
host and the downstream computer is routed through the SNAplus2 local
node. This enables a downstream computer to share a host connection
with SNAplus2 or with other downstream computers, instead of
requiring a direct link. For example, you can set up several downstream
computers connected to SNAplus2 over a local token ring network, so
that they all access the same long-distance SDLC leased line from
SNAplus2 to the host.
Using PU concentration also simplifies the configuration at the host. The
host configuration needs to include only the SNAplus2 computer and its
host communications link; the LUs at the downstream computers are
configured as part of the resources of the SNAplus2 computer. The host
computer is not aware that PU concentration is being used.
Before configuring PU concentration, you must perform the following
configuration tasks:
• Define the local node as described in "Configuring the Node".
• Configure a port and link station for dependent traffic between the
local node and the host, as described in Chapter 5, "Defining
Connectivity Components." Also, configure ports and link stations for
dependent traffic between the local node and the downstream nodes.
For downstream links, you can configure a template on the port to
support implicit downstream LUs (LUs that are not explicitly defined
on the local node).
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Chapter 9
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