Additional Details about Specifying Statements and Identifiers

This section provides more detailed information about specifying statements and identifiers in configuration mode:

• How to Specify Statements
• How the CLI Performs Type Checking

How to Specify Statements

This section provides more detailed information about CLI container and leaf statements so that you can better understand how the CLI displays them in a configuration and how you must specify them when creating ASCII configuration files.

Statements are shown one of two ways, either with braces or without:

• Statement name and identifier, with one or more lower-level statements enclosed in braces:

   < statement-name > < identifier > {
       statement; 
       additional-statements; 
   }
   
  

• Statement name, identifier, and a single identifier:

   < statement-name > < identifier > identifier; 
   
  

The statement-name is the statement name. In the configuration example shown in the previous section, ospf and area are statements.

The identifier is a name or other string that uniquely identifies an instance of a statement. The identifier is used when a statement can be specified more than once in a configuration. In the configuration example shown in the previous section, the identifier for the area statement is 0 and the identifier for the interface statement is so-0/0/0.

When specifying a statement, you must specify either a statement name or an identifier, or both, depending on the statement hierarchy.

You specify identifiers in one of the following ways:

• identifier—The identifier is a flag, which is a single keyword.
• identifier value—The identifier is a keyword, and the value is a required variable option.
• identifier [value1 value 2 value3 ...]—The identifier is a set that accepts multiple values. The brackets are required when you specify a set of identifiers; however, they are optional when you specify only one identifier.

The following examples illustrate how statements and identifiers are specified in the configuration:

 protocol {                                            # Top-level statement (statement-name).
     ospf {                                        # Statement under "protocol" (statement-name).
         area 0.0.0.0 {                                    # OSPF area "0.0.0.0" (statement-name identifier),
             interface so-0/0/0 {                                # which contains an interface named "so-0/0/0."
                 hello-interval 25;                            # Identifier and value (identifier-name value). 
                 priority 2;                            # Identifier and value (identifier-name value).
                 disable;                            # Flag identifier (identifier-name).
             }
             interface so-0/0/1;                                # Another instance of "interface," named so-0/0/1,
         }                                    # this instance contains no data, so no braces
     }                                        # are displayed.
 }
 policy-options {                                            # Top-level statement (statement-name).
     term term1 {                                        # Statement under "policy-options" 
                                             # (statement-name value).
         from {                                    # Statement under "term" (statement-name).
             route-filter 10.0.0.0/8 orlonger reject;                                                                # One identifier ("route-filter") with
             route-filter 127.0.0.0/8 orlonger reject;                                                                # multiple values.
             route-filter 128.0.0.0/16 orlonger reject;
             route-filter 149.20.64.0/24 orlonger reject;
             route-filter 172.16.0.0/12 orlonger reject;
             route-filter 191.255.0.0/16 orlonger reject;
         }
         then {                            # Statement under "term" (statement-name).
             next term;                        # Identifier (identifier-name).
         }
     }
 }

When you create an ASCII configuration file, you can specify statements and identifiers in one of the following ways. However, each statement has a preferred style, and the CLI uses that style when displaying the configuration in response to a configuration mode show command.

• Statement followed by identifiers:

   statement-name identifier-name [...] identifier-name value [...];
   
  

• Statement followed by identifiers enclosed in braces:

   statement-name { 
       identifier-name; 
       [...] 
       identifier-name value;
       [...]
   }
   
  

• For some repeating identifiers, you can use one set of braces for all the statements:

   statement-name {
       identifier-name value1; 
       identifier-name value2; 
   }