Configuring APPC Communication
Defining Modes and Classes of ServiceDefining Modes and Classes of Service
A mode specifies a set of characteristics that a local LU (LU type 6.2) uses to communicate with its partner LU. These characteristics include information about the way data is transmitted between the two LUs (such as maximum RU lengths and pacing window sizes), and about whether the LUs can establish parallel sessions.
In addition, you may need to specify requirements for the communication path between the LUs, such as enforcing a certain level of network security, minimizing transmission time, or avoiding the use of expensive communication links. You can define these requirements using a class of service (COS), which specifies minimum and maximum acceptable values for characteristics such as transmission time, transmission cost, and network security. The COS also specifies weightings associated with different ranges of these values. This enables the node to calculate the best route across the network when two or more routes to the same remote LU are available.
You do not need to associate a COS with the mode; the COS name is determined dynamically.
SNA defines a number of standard modes and associated COSs that cover the requirements of most systems; you generally do not need to define additional modes and COSs. You need to define a mode only if the required mode is not one of the predefined standard modes, which can be viewed in the Modes window.
The default mode is used if the mode name in an incoming conversation is unrecognized. If you do not specify a default mode, the default mode is the blank mode name.
The standard mode names and their associated COS names are shown in Table
194 | Chapter 7 |