12.2 Configuration

The previous section talked about error model, in this section we discuss how to use error models in ns.

To use an error model, it has to be inserted into a SimpleLink object. Because a SimpleLink is a composite object (Chapter 6), an error model can be inserted to many places. Currently we provide the following methods to insert an error module into three different places.

• Insert an error module in a SimpleLink BEFORE the queue module. This is provided by the following two OTcl methods:

  
  
  

• Insert an error module in a SimpleLink AFTER the queue but BEFORE the delay link. This is provided by the following two methods:

  
  
  The nam traces generated by error models inserted using these two methods do not require special treatment and can be visualized using an older version of nam.

• Insert an error module in a Link AFTER the delay link module. This can be done by Link::install-error. Currently this API doesn't produce any trace. It only serves as a placeholder for possible future extensions.