Use this command to create IPv6 prefix lists. An IPv6 prefix list can contain only ipv6 addresses. Prefix lists allow matching of route prefixes with those specified in the prefix list. Each prefix list includes of a sequence of prefix list entries ordered by their sequence numbers. A router sequentially examines each prefix list entry to determine if the route‘s prefix matches that of the entry. For IPv6 routes, only IPv6 prefix lists are matched. An empty or nonexistent prefix list permits all prefixes. An implicit deny is assumed if a given prefix does not match any entries of a prefix list. Once a match or deny occurs the router does not go through the rest of the list. An IPv6 prefix list may be used within a route map to match a route‘s prefix using the match ipv6 address command. A route map may contain both IPv4 and IPv4 prefix lists. If a route being matched is an IPv6 route, only the IPv6 prefix lists are matched.
Up to 128 prefix lists may be configured. The maximum number of statements allowed in prefix list is 64. These numbers indicate only IPv6 prefix lists. IPv4 prefix lists may be configured in appropriate numbers independently.
| Default | No prefix lists are configured by default. When neither the ge nor the le option is configured, the destination prefix must match the network/length exactly. If the ge option is configured without the le option, any prefix with a network mask greater than or equal to the ge value is considered a match. Similarly, if the le option is configured without the ge option, a prefix with a network mask less than or equal to the le value is considered a match. |
| Format | ipv6 prefix-list list-name [seq seq-number] { {permit/deny} ipv6-prefix/prefix-length [ge ge-value] [le le-value] | description text | renumber renumber-interval first-statement-number} |
| Mode | Global Configuration |
| Parameter | Description |
|---|---|
| list-name | The text name of the prefix list. Up to 32 characters. |
| seq number | (Optional) The sequence number for this prefix list statement. Prefix list statements are ordered from lowest sequence number to highest and applied in that order. If you do not specify a sequence number, the system will automatically select a sequence number five larger than the last sequence number in the list. Two statements may not be configured with the same sequence number. The value ranges from 1 to 4,294,967,294. |
| permit | Permit routes whose destination prefix matches the statement. |
| deny | Deny routes whose destination prefix matches the statement. |
| ipv6-prefix/prefix-length | Specifies the match criteria for routes being compared to the prefix list statement. The ipv6-prefix can be any valid IPv6 prefix where the address is specified in hexadecimal using 16-bit values between colons. The prefix-length is the The length of the IPv6 prefix, given as a decimal value that indicates how many of the high-order contiguous bits of the address comprise the prefix (the network portion of the address). A slash mark must precede the decimal value. |
| ge length | (Optional) If this option is configured, specifies a prefix length greater than or equal to the ipv6-prefix/prefix-length. It is the lowest value of a range of the length. |
| le length | (Optional) If this option is configured, specifies a prefix length less than or equal to the ipv6-prefix/prefix-length. It is the highest value of a range of the length. |
| Description | A description of the prefix list. It can be up to 80 characters in length. |
| renumber | (Optional) Provides the option to renumber the sequence numbers of the IPv6 prefix list statements with a given interval starting from a particular sequence number. |
The following example configures a prefix list that allows routes with one of two specific destination prefixes, 2001::/64 and 5F00::/48:
(R1)(config)# ipv6 prefix-list apple seq 10 permit 2001::/64 (R1)(config)# ipv6 prefix-list apple seq 20 permit 5F00::/48
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