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 name of the statement. In the configuration example shown in the previous section, ospf and area are statement names.

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 option variable.
• 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; 

}