Network nodes maintain information about all network nodes and links between network nodes. When a session is requested, a mode is specified. Each node contains a class of service (COS) parameter that specifies the class of service description that will be used to calculate the route the session will take. The class of service also specifies the transmission priority that will govern the rate of data transfer after the session has been established.
The following class-of-service descriptions are shipped with the iSeries system:
If you need to force a particular route to be selected, a user class of service (COSD) can be created. See Create a class-of-service description for a thorough explanation.