ip prefix-list

This command creates an IPv4 prefix list.

Syntax

ip prefix-list name [seq seq-value] {deny | permit} {prefix/length} [source-address] [next-hop] [ge length] [le length] [nlri]

no ip prefix-list name [seq seq-value] {deny | permit} {network/masklen}  [ge length] [le length]

Parameters

`name`	Specifies the name of the prefix list as a string of characters.
seq `seq-value`	(Optional) Specifies the prefix list entry as an integer between 1 and 65535, inclusive.
deny \| permit	Specifies that matching prefixes for the specified source address or next hop are denied or permitted.
deny	Specifies that matching prefixes for the specified source address or next hop are denied.
`prefix/length`	Specifies a valid IPv4 prefix and length.
source-address	(Optional) Specifies that the configured parameters are matched against the IPv4 source address
next-hop	(Optional) Specifies that configured parameters are matched against the next hop attribute.
ge `length`	(Optional) Specifies that the IPv4 address matches (prefix, length) pairs with exactly the same prefix address and length that are greater than or equal to the value of the ge command. This value can be in the range of 0 to 32, but it must be at least the value of length and no greater than the value of le.
le `length`	(Optional) Specifies that the IPv4 address matches (prefix, length) pairs with exactly the same prefix address and length that are less than or equal to the value of the le command. This value can be in the range of 0 to 32, but it must be at least the value of length and no less than the value of ge.
nlri	(Optional) Specifies that the configured parameters are matched against the Network Layer Reachability Information (NLRI).

Defaults

If the seq option is not specified, sequence number is generated automatically in increments of 5, starting with 0.
If the source-address option is not specified, the match is not based upon the source address for this prefix.
If the next-hop option is not specified, the match is not based upon the next hop attribute for this prefix.
If the ge and le options are not specified, an exact match is assumed.
If the ge option is not specified and the le option is, the range is assumed to be less than or equal to the le length.
If the le option is not specified and the ge option is, then the range is assumed to be from the specified ge length to 32.

Mode

Router global configuration.

Usage

Prefix lists simulate a sequential lookup and return the first matched entry as the true match. The entries are ordered according to the sequential value. Sequence numbers are generated automatically in increments of 5 starting with 0, unless the sequence option is specified.

The optional ge and le commands can be used to specify the range of the prefix length to be matched for prefixes that are more specific than a network and netmask value.

Configured prefix lists are used in BGP route-maps. A configured prefix-list is associated with a BGP route-map using the match prefix-list command in a BGP route-map configuration context.

The deny prefix-list match type should only be used for prefix-lists referenced by BGP route-maps with the ORF association set to local. Otherwise the permit/deny type of the route-map is used.

The no prefix-list command deletes all entries or specified entries in a prefix list. One way to remove a specific entry from a prefix list is to specify all parameters that were specified when the entry was created. Another way is to specify the sequence number of the entry.

Examples

The following example configures a prefix list “abc” that permits all prefixes in 128.0.0.0/8 with a prefix length of 24.

System(su-config)->ip prefix-list abc permit 128.0.0.0/8 ge 24 le 24

The following example configures a prefix list “abc” and permits all routes matching 10.0.0.0/24 with prefix length greater than or equal to 16:

System(su-config)->ip prefix-list abc seq 10 permit 10.0.0.0/24 ge 16

Published May 2016prev | next

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