Extending Data Models

Extending data models (augment)

YANG allows a module to insert additional nodes into data models. This is useful for helping vendors to add vendor-specific parameters to standard data models in an interoperable way.

The "augment" statement defines the location in the data model hierarchy where new nodes are inserted, and the "when" statement defines the conditions when the new nodes are valid.

YANG example:

augment /system/login/user {
 when "class != 'wheel'";
 leaf uid {
  type uint16 {
   range "1000 .. 30000";
  }
 }
}

This example defines a "uid" node that is valid only when the user's "class" is not "wheel".