Usage Guidelines

No specific guidelines impact the use of this command.

Usage Guidelines

If the add value is greater than the maximum allowed value, the metric is added. If the resulting metric exceeds the maximum for the routing protocol, then the route is dropped (by the client routing protocol).

Usage Guidelines

Use the apply command to execute a policy (either parameterized or unparameterized) from within another policy, which allows for the reuse of common blocks of policy.

Wildcards can be used in apply policy names. This supports the nested wildcard apply scenario. A wildcard is specified by inserting an asterisk (*) in place of one of the portions of the apply policy name; the wildcard indicates that any value for that portion of the apply policy name matches. The nested wildcard apply policy allows wildcard (*) based apply nesting. The wildcard operation permits declaration of a generic apply statement that calls all policies that contain a specific defined set of alphanumeric characters, defined on the router.

Usage Guidelines

Use the as-path in command as a conditional expression within an if statement to match the AS path of a route to an AS path set. The AS path is a sequence of autonomous system numbers traversed by a route.

Note	For a list of all conditional expressions available within an if statement, see the if command.

The as-path in command evaluates to true if at least one of the regular expressions defined in the associated AS path set matches the AS path attribute of the route.

In the case where the AS path set is defined but contains no elements in it, the as-path in conditional expression command returns false.

Usage Guidelines

Use the as-path is-local command as a conditional expression within an if statement to determine if this router (or another router within this autonomous system or confederation) originated the route.

Note	For a list of all conditional expressions available within an if statement, see the if command.

Routes that are locally originated within the autonomous system or confederation carry an empty AS path. For the Border Gateway Protocol (BGP) specification, when a route is advertised across the autonomous system boundary or a confederation boundary, the local autonomous system number or confederation ID is appended to the autonomous system path. The AS path of a locally originated aggregate is also empty unless it has been modified by policy.

The is-local operator evaluates to true for autonomous system paths that are empty. An empty AS path is how an AS path that is local to our autonomous system is represented in BGP.

Usage Guidelines

Use the as-path length command as a conditional expression within an if statement to perform a conditional check based on the length of the AS path.

Note	For a list of all conditional expressions available within an if statement, see the if command.

This command takes either a specific integer value or a range of integer values specified with the ge and le operators. Any or all these integers can be parameterized. The operator counts one for each autonomous system in the path. In the case where the route may be aggregated and contain one or more AS sets, the length operator adds one for each set present, the occurrence of an AS set typically indicates that this route is an aggregated route, and the aggregated route had a component route that contained one of the autonomous systems in the set. Likewise, in the case of confederations, a count of one is added for each confederation in the path or each confederation set in the path. A null AS path has a length of zero.

Usage Guidelines

Use the as-path neighbor-is command as a conditional expression within an if statement to test the autonomous system number or numbers at the head of the AS path against a sequence of one or more integral values or parameters. In other words, to test to learn if the sequence of autonomous system numbers matches the path beginning with the neighboring autonomous system from which this route was heard.

Note	For a list of all conditional expressions available within an if statement, see the if command.

This command has an equivalent regular expression (ios-regex). For example, AS path neighbor-is ‘1’ would be ‘^1_’.

Usage Guidelines

Use the as-path originates-from command as a conditional expression within an if statement to compare an AS path to the autonomous system sequence.

Note	For a list of all conditional expressions available within an if statement, see the if command.

The originates-from operator is similar to the neighbor-is operator, except that it looks at the autonomous system number at the opposite end of the AS path. In other words, it is comparing to the autonomous system that originated the route. It can take numbers or parameters, enclosed in single quotation marks, that represent a sequence of autonomous system numbers. When more than one number is specified in the list, the sequence of autonomous system numbers listed must appear as a subsequence in the AS path, with the last number corresponding to the autonomous system that originated the route.

Usage Guidelines

Use the as-path passes-through command as a conditional expression within an if statement to verify if the specified integer or parameter appears anywhere in the AS path or if the sequence of integers and parameters appears.

Note	For a list of all conditional expressions available within an if statement, see the if command.

The passes-through operator takes a sequence of integers or parameters, enclosed in single quotation marks, as an argument. It can also take a single integer or parameter as an argument. It evaluates to true if the supplied integer or parameter appears anywhere in the AS path, or if the supplied sequence of integers and parameters appears, in the same order, anywhere in the AS path. This includes the originates-from or neighbor-is location in the AS path.

Usage Guidelines

Use the as-path-set command to create a named AS path set.

An AS path set comprises operations for matching an AS path attribute.

This command enters AS path set configuration mode, in which you can use any of the below option to specify an operation.

The above options can also be used as an inline set in a parenthesized list of comma-separated expressions.

Usage Guidelines

Use the as-path unique-length command as a conditional expression within an if statement to perform a match based on the length of the AS path.

Note	For a list of all conditional expressions available within an if statement, see the if command.

The unique-length operator is similar to the length operator, except that when an AS path has been padded with the same autonomous system number multiple times, the operator counts only one when the route is padded. Therefore, given an AS path of 333 333 111 222 123 444 444 444, the unique-length operator would return a value of 5, whereas the length operator would return a value of 8.

Usage Guidelines

Use the community is-empty command as a conditional expression within an if statement to check if a route has community attributes associated with it.

Note	For a list of all conditional expressions available within an if statement, see the if command.

This command takes no arguments and evaluates to true only if the route has no community attributes associated with it.

Usage Guidelines

Use the community matches-any command as a conditional expression within an if statement to match any element of a community set.

Note	For a list of all conditional expressions available within an if statement, see the if command.

A simple condition using the matches-any operator evaluates as true if at least one community element of the community attribute for the route matches an element in the community set operand. If no community in the route matches any of the specifications in the named or inline set, then the condition evaluates to false. Likewise, when there is no community at all in the route, the condition evaluates to false.

Matching of a community in the route to a specification in a named or an inline set is intuitive. If the community specification in a set is the familiar colon-separated decimal 16-bit numbers specification, or one of the well-known communities, the community matches the specification if the specification denotes the same 32-bit number as that in the route. If the community specification uses a wildcard, then the community in the route matches if it is one of the many communities denoted by the wildcard specification. In inline sets, community specifications may be parameterized, in which case the relevant matching is done when the value of the parameter has been supplied.

Communities may also be matched using range and regular expression operators. Range specifications are entered as follows: [ low-value .. high-value ]. Either or both colon-separated halves of a community value may contain a range. The following are valid range specifications:

  10:[100..1000]
  [10..100]:80
  [10..100]:[100..2000]
  
  

In addition, the private-as keyword may be used to specify the range from 64512 to 65534. Regular expressions are specified as the ios-regex keyword followed by a valid regular expression string.

Community values from the route are matched one at a time to the match specifications. Therefore, regex match specifications are expected to represent one individual community value and not a sequence of community values.

Usage Guidelines

Use the community matches-every command as a conditional expression within an if statement to match every element of a community set.

Note	For a list of all conditional expressions available within an if statement, see the if command.

A simple condition using the matches-every operator evaluates as true if every specification in the named set or inline set specified matches at least one community value in the route. If any community specification in the named or inline set is not matched, then the operation evaluates to false.

Matching of a community in the route to a specification in a named or an inline set is intuitive. If the community-specification in a set is the familiar colon-separated decimal 16-bit numbers specification, or one of the well-known communities, the community matches the specification if the specification denotes the same 32-bit number as that in the route. If the community specification uses a wildcard, then the community in the route matches if it is one of the many communities denoted by the wildcard specification. In inline sets, community specifications may be parameterized, in which case the relevant matching is done when the value of the parameter has been supplied.

Communities may also be matched using range and regular expression operators. Range specifications are entered as follows: [ low-value .. high-value ]. Either or both colon-separated halves of a community value may contain a range. The following are valid range specifications:

  10:[100..1000]
  [10..100]:80
  [10..100]:[100..2000]
  
  

Therefore, a matches-every operation with two community range specifications means that a community must be present in the route that corresponds to each range. For example, in the following statement:

  if community matches-every (10:[100..200],20:[100..200]) then
  
  

the statement evaluates as true if one or more communities in the route lie in the range 10:[100.200] and one or more communities in the route lie in the range 20:[100..200].

In addition, the private-as keyword may be used to specify the range from 64512 to 65534.

Regular expressions are specified as the ios-regex keyword followed by a valid single-quoted regular expression string. Community values from the route are matched one at a time against the match specifications. Therefore, regex match specifications are expected to represent one individual community value and not a sequence of community values.

Usage Guidelines

This command is similar to the community matches-any command, but every community in the route must match at least one match specification. If the route has no communities, then it matches.

Note	For a list of all conditional expressions available within an if statement, see the if command.

Usage Guidelines

Regular expressions and ranges can be specified to match the communities. An attempt to use a community set that contains a range or regular expression to set a community value is rejected when an attempt to attach such a policy is made.

A community set holds community values for matching against the Border Gateway Protocol (BGP) community attribute. A community is a 32-bit quantity. For notational convenience, each community value must be split in half and expressed as two unsigned decimal integers in the range from 0 to 65535, separated by a colon.

The inline form of a community set also supports parameterization. Each 16-bit portion of the community may be parameterized.

The routing policy language (RPL) provides symbolic names for the standard well-known community values: accept-own is 0xFFFF0001, internet is 0:0, no-export is 65535:65281, no-advertise is 65535:65282, and local-as is 65535:65283.

RPL also provides a facility for using wildcards in community specifications. A wildcard is specified by inserting an asterisk (*) in place of one of the 16-bit portions of the community specification, which indicates that any value for that portion of the community matches.

Every community set must contain at least one community value. An empty community set is invalid and the policy configuration system rejects it.

Community sets can be entered in these formats:

Format	Description
#-remark	Remark beginning with '#'
*	Wildcard (any community or part thereof)
0-65535	16-bit half-community number
[	Left bracket to begin range
accept-own	Accept-Own (BGP well-known community)
dfa-regex	DFA (deterministic finite automata) style regular expression
internet	Internet (BGP well-known community)
ios-regex	Traditional IOS style regular expression
local-AS	Do not send outside local AS (BGP well-known community)
no-advertise	Do not advertise to any peer (BGP well-known community)
no-export	Do not export to next AS (BGP well-known community)
private-as	Match within BGP private AS range [64512..65534]

Note

The dfa-regex and ios-regex syntax for community set is "['][^':&<> ]*:[^':&<> ]*[']" . This means that regex starts with a single-quote (") followed by a string of any character (that does not include single-quote, colon, ampersand, less-than, greater-than, or space) followed by a colon, and a string of any characters (that does not include single-quote, colon, ampersand, less-than, greater-than, or space) followed by single-quote.

Usage Guidelines

Use the delete community command to delete community attributes associated with a BGP route.

Note	The delete community command can be used as an action statement within an if statement. For a list of all action statements available within an if statement, see the if command.

Communities are 32-bit values carried in Border Gateway Protocol (BGP) routes. Each route may have zero or more communities in an unordered list.

You can remove a well-known community (internet, no-export, no-advertise, or local-as) from a route, but this removal must be done explicitly. This command should be used with a degree of caution. In general, few circumstances exist in which you would need to remove a well-known community.

Usage Guidelines

Use the delete extcommunity rt command to delete extended community values from a BGP route target extended community list in a route.

Note	The delete extcommunity rt command can be used as an action statement within an if statement. For a list of all action statements available within an if statement, see the if command.

Extended communities are similar to regular Border Gateway Protocol (BGP) communities but contain more data and have a richer structure for encoding information in them.

Extended communities can be in the following forms: SoO:AS:tag, SoO:IP:tag, RT:AS:tag, or RT:IP:tag.

Wildcards (*) and regular expressions are allowed for extended community set elements.

The forms of this command that take a named extended community set or an inline extended community set value as arguments are equivalent. They delete any extended communities that are listed in either the named set or the inline set, respectively.

Usage Guidelines

The large communities are specified as three non negative decimal integers separated by colons. For example, 1:2:3. Each integer is stored in 32 bits. The possible range for each integer is 0 to 4294967295.

In route-policy statements, each integer in the BGP large community can be replaced by any of the following expressions:

• [x..y] — This expression specifies a range between x and y, inclusive.

• * — This expression stands for any number.

• peeras — This expression is replaced by the AS number of the neigbhor from which the community is received or to which the community is sent, as appropriate.

• not-peeras — This expression matches any number other than the peeras.

• private-as — This expression specifies any number in the private ASN range: [64512..65534] and [4200000000..4294967294].

Note	The peeras and not-peeras expressions can only be used in delete statements that appear in route policies that are applied at the neighbor-in or neighbor-out attach points.

IOS regular expression (ios-regex) and DFA style regular expression (dfa-regex) can be used in the delete statements. For example, the IOS regular expression ios-regex '^5:.*:7$' is equivalent to the expression 5:*:7.

Usage Guidelines

Use the destination in command as a conditional expression within an if statement to match a destination entry in a named prefix set or inline prefix set.

Note	For a list of all conditional expressions available within an if statement, see the if command.

This command takes either a named prefix set or an inline prefix set value as an argument. The condition returns true if the destination entry matches any entry in the prefix set or inline prefix set. An attempt to match a destination using a prefix set that is defined but contains no elements returns false.

The routing policy language (RPL) provides the ability to test destinations for a match to a list of prefix match specifications using the in operator. The destination in command is protocol-independent.

In Border Gateway Protocol (BGP), the destination of a route is also known as its network-layer reachability information (NLRI). It comprises a prefix value and a mask length.

RPL supports both 32-bit IPv4 prefixes, specified in dotted-decimal format, and 128-bit IPv6 prefixes, specified in colon-separated hexadecimal format.

Usage Guidelines

Use the done command to stop executing the policy and accept the route.

Note	The done command can be used as an action statement within an if statement. For a list of all action statements available within an if statement, see the if command.

When encountering a done statement the route is passed and no further policy statements are executed. All modifications made to the route prior to the done statement are still valid.

Note

The default action of a route policy is to drop or discard any routes that have not been either explicitly passed or for which no attempt has been made to modify with an action. The routing policy language (RPL) does not have specific “match clauses,” which means the default drop behavior is controlled by whether a route has been explicitly passed or an attempt has been to modify the route using an action statement.

Usage Guidelines

Use the drop command within a route policy to drop a route.

Note	The drop command can be used as an action statement within an if statement. For a list of all action statements available within an if statement, see the if command.

This command causes the route to be dropped. After a route is dropped, no further execution of policy occurs. Therefore, if after executing the first two statements of a policy the drop statement is encountered, the route is discarded and execution stops immediately even when the policy contains further statements.

Note

The default action of a route policy is to drop or discard any routes that have not been either explicitly passed or attempted to be modified with an action. The routing policy language (RPL) does not have specific “match clauses,” which means the default drop behavior is controlled by whether a route has been explicitly passed or an attempt has been to modify the route using an action statement.

Usage Guidelines

Use the edit command to edit the contents of a route policy, a prefix set, an AS path set, a community set, an extended community set, a global policy, or a route destination set.

After editing with Nano, save the edit buffer and exit the editor using the Ctrl-X keystroke.

After editing with Emacs, save the editor buffer by using the Ctrl-X and Ctrl-S keystrokes. To save and exit the editor, use the Ctrl-X and Ctrl-C keystrokes.

After editing with VIM, to write to a current file and exit use the :wq or :x or ZZ keystrokes. To quit and confirm, use the :q keystrokes. To quit and discard changes, use the :q! keystrokes.

Usage Guidelines

Use the end-global command to end the definition of global parameters and exit global parameter configuration mode.

Usage Guidelines

Use the end-policy command to end the definition of a route policy and exit route-policy configuration mode.

Usage Guidelines

Use the end-set command to end the definition of an AS path set, a prefix set, a community set, or an extended community set.

Usage Guidelines

Use the extcommunity rt is-empty command as a conditional expression within an if statement to check if a BGP route has extended community attributes associated with it.

Note	For a list of all conditional expressions available within an if statement, see the if command.

The is-empty operator takes no arguments and evaluates to true if the route has no extended community attributes associated with it.

Usage Guidelines

Use the extcommunity rt matches-any command as a conditional expression within an if statement to match elements of an extended community set.

Note	For a list of all conditional expressions available within an if statement, see the if command.

A simple condition using the matches-any operator evaluates as true if at least one extended community in the route matches an extended community specification in the named or inline set. If no extended community in the route matches any of the specifications in the named or inline set, then this simple condition evaluates to false. Likewise, when there is no extended community at all in the route, the condition evaluates to false.

Matching an extended community in the route to a specification in a named or an inline set is intuitive. In inline sets, extended community specifications may be parameterized, in which case the relevant matching is done when the value of the parameter has been supplied.

Usage Guidelines

Use the extcommunity rt matches-every command as a conditional expression within an if statement to match every element of an RT extended community set.

Note	For a list of all conditional expressions available within an if statement, see the if command.

A simple condition using the matches-every operator evaluates as true if every extended community value in the extended community attribute for the route matches at least one element of the extended community set or inline set. If no extended community in the route matches any of the specifications in the named or inline set, then this simple condition evaluates to false. Likewise, when there is no extended community at all in the route, the condition evaluates to false.

Matching an extended community in the route to a specification in a named or an inline set is intuitive. In inline sets, extended community specifications may be parameterized, in which case the relevant matching is done when the value of the parameter has been supplied.

Usage Guidelines

Use the extcommunity rt matches-within command as a conditional expression within an if statement to match elements of an extended community set.

Note	For a list of all conditional expressions available within an if statement, see the if command.

A simple condition using the matches-within operator evaluates as true if all the elements in extended community from the route match any element in the extended community set. For example, let 'c' be the RTs from the route and 'm' be the RT set from the policy. With the extcommunity rt matches-within configuration, each value in 'c' must match any (or at least one) value in 'm'.

Matching an extended community in the route to a specification in a named or an inline set is intuitive. In inline sets, extended community specifications may be parameterized, in which case the relevant matching is done when the value of the parameter has been supplied.

Usage Guidelines

Use the extcommunity-set cost command to define a cost extended community set.

An extended community set is analogous to a community set except that it contains extended community values instead of regular community values. Extended community values are 64-bit structured values. An extended community set also supports named forms and inline forms.

Cost extended communities can be entered in these formats:

• #-remark ---Remark beginning with '#'

• 0-255 ---Decimal number

• abort ---Discard RPL definition and return to top level config

• end-set ---End of set definition

• exit ---Exit from the submode

• igp: ---Cost Community with IGP as point of insertion

• pre-bestpath: ---Cost Community with Pre-Bestpath as point of insertion

• show ---Show partial RPL configuration

Multiple cost community set clauses can be configured in each route policy block or sequence. Each cost community set clause must have a different ID (0-255). The cost community set clause with the lowest cost-value is preferred by the best path selection process when all other attributes are equal.

As with community sets, the inline form supports parameterization within parameterized policies. Either portion of the extended community value can be parameterized.

Every extended community set must contain at least one extended community value. Empty extended community sets are invalid and the policy configuration system rejects them.

Wildcards (*) and regular expressions are allowed for extended community set elements.

Usage Guidelines

Use the extcommunity-set rt command to define an RT extended community set for BGP.

Regular expressions and ranges can be specified to match the extended communities. Regular expressions and ranges can be specified in an extended community set to support the matching of communities. An attempt to use an extended community set that contains a range or regular expression to set an extended community set value is rejected when an attempt to attach such a policy is made.

An extcommunity set RT holds RT extended community values to match against the Border Gateway Protocol (BGP) RT extended community attribute. RT extended communities can be entered in these formats:

• #-remark ---Remark beginning with '#'

• * --- Wildcard (any community or part thereof)

• 1-4294967295 ---32-bit decimal number

• 1-65535 ---16-bit decimal number

• A.B.C.D/M:N ---Extended community - IPv4 prefix format

• A.B.C.D:N ---Extended community - IPv4 format

• ASN:N ---Extended community - ASPLAIN format

• X.Y:N ---Extended community - ASDOT format

• dfa-regex ---DFA (deterministic finite automata) style regular expression

• ios-regex ---Traditional IOS style regular expression

  Note

  The dfa-regex and ios-regex syntax for community set is "['][^':&<> ]*:[^':&<> ]*[']" . This means that regex starts with a single-quote (") followed by a string of any character (that does not include single-quote, colon, ampersand, less-than, greater-than, or space) followed by a colon, and a string of any characters (that does not include single-quote, colon, ampersand, less-than, greater-than, or space) followed by single-quote.

N is a number within the range of 1 to 65535.

Usage Guidelines

Use the extcommunity-set soo command to define an SoO extended community set.

An extcommunity set soo holds SoO extended community values to match against the Border Gateway Protocol (BGP) SoO extended community attribute. SoO extended communities can be entered in these formats:

• #-remark ---Remark beginning with '#'

• * --- Wildcard (any community or part thereof)

• 1-4294967295 ---32-bit decimal number

• 1-65535 ---16-bit decimal number

• A.B.C.D/M:N ---Extended community - IPv4 prefix format

• A.B.C.D:N ---Extended community - IPv4 format

• ASN:N ---Extended community - ASPLAIN format

• X.Y:N ---Extended community - ASDOT format

• abort ---Discard RPL definition and return to top level config

• dfa-regex ---DFA style regular expression

• end-set ---End of set definition

• exit ---Exit from the submode

• ios-regex ---Traditional IOS style regular expression

• show ---Show partial RPL configuration

N is a site-specific number.

Usage Guidelines

Use the extcommunity soo is-empty command as a conditional expression within an if statement to check if a BGP SoO route has extended community attributes associated with it.

Note	For a list of all conditional expressions available within an if statement, see the if command.

The is-empty operator takes no arguments and evaluates to true if the route has no SoO extended community attributes associated with it.

Usage Guidelines

Use the extcommunity soo matches-any command as a conditional expression within an if statement to match elements of an extended community set.

Note	For a list of all conditional expressions available within an if statement, see the if command.

A simple condition using the matches-any operator evaluates as true if at least one extended community in the route matches an extended community specification in the named or inline set. If no extended community in the route matches any of the specifications in the named or inline set, then this simple condition evaluates to false. Likewise, when there is no extended community at all in the route, the condition evaluates to false.

Matching an extended community in the route to a specification in a named or an inline set is intuitive. In inline sets, extended community specifications may be parameterized, in which case the relevant matching is done when the value of the parameter has been supplied.

Usage Guidelines

Use the extcommunity soo matches-every command as a conditional expression within an if statement to match every element of a SoO extended community set.

Note	For a list of all conditional expressions available within an if statement, see the if command.

A simple condition using the matches-every operator evaluates as true if every extended community value in the extended community attribute for the route matches at least one element of the extended community set or inline set. If no extended community in the route matches any of the specifications in the named or inline set, then this simple condition evaluates to false. Likewise, when there is no extended community at all in the route, the condition evaluates to false.

Matching an extended community in the route to a specification in a named or an inline set is intuitive. In inline sets, extended community specifications may be parameterized, in which case the relevant matching is done when the value of the parameter has been supplied.

Usage Guidelines

The if command uses a conditional expression to decide which actions or dispositions should be taken for a given route. Table 1 lists the conditional expressions.

An action statement is a sequence of operations that modify a route, most of which are distinguished by the set keyword. In a route policy, these operations can be grouped. Table 2 lists the action statements.

Route-policy policy_name
If apply policyA and apply policyB then
Set med 100
Else if not apply policyD then
Set med 200
Else
Set med 300
Endif
End-policy

Usage Guidelines

No specific guidelines impact the use of this command.

Usage Guidelines

None

Usage Guidelines

No specific guidelines impact the use of this command.

Usage Guidelines

No specific guidelines impact the use of this command.

Usage Guidelines

No specific guidelines impact the use of this command.

Usage Guidelines

Use the local- preference command as a conditional expression within an if statement to compare the local-preference attribute to an integer value or a parameterized value.

Note	For a list of all conditional expressions available within an if statement, see the if command.

The MED is a 32-bit unsigned integer. The eq operation compares the local-preference to either a static value or a parameterized value passed to a parameterized policy for equality with that value. A greater than or equal to comparison can also be done with the ge operator, and a less than or equal to comparison can be performed using the le operator.

Usage Guidelines

Use the large community is-empty command as a conditional expression within an if statement to check if a route has community attributes associated with it.

Note	For a list of all conditional expressions available within an if statement, see the if command.

This command takes no arguments and evaluates to true only if the route has no community attributes associated with it.