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    Creating or Configuring an IP or IPv6 Prefix List for Route Filtering

    You can use the ip prefix-list and ipv6 prefix-list commands to create a prefix list for route filtering and to specify a list entry—a deny or permit clause for a network address—to the prefix list. You can add entries to prefix lists. The prefix list name can be up to 32 characters long.

    You can specify the position of each entry in the list with the seq (sequence) keyword. If you do not specify a sequence number, the router uses the value of the last sequence number plus 5.

    You can use the ge and le keywords to specify a range of network prefixes. These keywords have the following values:

    • prefix length < ge <= 32
    • prefix length < le <= ge

    If you do not specify either the ge or le keyword, an exact match is expected.

    To create a prefix list for route filtering:

    • Create an IPv4 prefix list to permit only a route with a prefix length of 8 and a network address of 151.0.0.0 (exact match required).
      host1(config)#ip prefix-list abc permit 151.0.0.0/8
    • Create an IPv6 prefix list to permit only a route with a prefix length of 8 and a network address of 1:0:0:0:0:0:0:5 (exact match required).
      host1(config)#ipv6 prefix-list abc permit 1::5/8

    Use the no version to remove the specified prefix list or the specified list entry.

    Published: 2014-08-12