segment access host applications through the 3745 (FEP) gateway by using the locally
administered address (LAA) assigned to the Token Interface Coupler as the destination address.
(LAA is defined later in this chapter.) Token Ring devices can appear as either PU type 2 or as
an LU, depending on the type of gateway selected. This section discusses the two categories of
gateways, along with LAAs. We will also look at a device called a Downstream Physical Unit,
often the subject of test material with SNA environments.
a cluster controller, not a FEP, so the burden of converting addresses that are destined for nodes
on the Token Ring is now on the host. Figure 12-15 depicts this. Notice in the figure that each
node has a session with the SSCP.
the preceding two figures.
12-16. An application such as Novell's SAA Gateway can appear as a PU node type 2 on
the same gateway device.