Considerations for network attributes that can affect APPC error recovery

Network attributes control information about the communications environment. Allow APPN virtual controller support (ALWVRTAPPN), and virtual controller autocreate APPC device limit (VRTAUTODEV) are network attributes that play a role when a communications error occurs.

The following information explains more about each network attribute and how the attribute affects system performance during error recovery.

• Allow APPN virtual controller support (ALWVRTAPPN) controls whether APPN devices should be attached to real APPN controllers, or to a virtual controller.
  • The default value is *NO.
  • Use virtual APPN controllers to limit the number of devices that go into error recovery when a failure occurs.
  • May be used to eliminate multiple device descriptions that can get created when multiple routes through the APPN network exist.
• Virtual controller autocreate APPC device limit (VRTAUTODEV) indicates the maximum number of automatically created APPC devices for each virtual controller when the following is true:
  • The Allow APPN Virtual Controller (ALWVRTAPPN) network attribute is *YES.
  • The Allow HPR Transport Tower (ALWHPRTWR) network attribute is *YES.

  The VRTAUTODEV network attribute specifies the upper limit for the number of automatically created APPC devices on virtual controllers. The more APPC devices created, the longer it takes the system to do error recovery processing on the controller. The default value on this network attribute is 100. For every 100 new APPN locations that your system communicates, a new virtual APPN controller is created.

  Note:
  Manually created devices may still be created if the VRTAUTODEV parameter value is less than the limit of 254.

For more information about these system values, see the following books:

• For more information about iSeries™ communications, see the Communications Management and Work Management books.