doc/user/filter.rst

   1 *********
   2 Filtering
   3 *********
   4
   5 FRR provides many very flexible filtering features. Filtering is used
   6 for both input and output of the routing information. Once filtering is
   7 defined, it can be applied in any direction.
   8
   9 IP Access List
  10 ==============
  11
  12 .. clicmd:: access-list NAME [seq (1-4294967295)] permit IPV4-NETWORK
  13
  14 .. clicmd:: access-list NAME [seq (1-4294967295)] deny IPV4-NETWORK
  15
  16    seq
  17       seq `number` can be set either automatically or manually. In the
  18       case that sequential numbers are set manually, the user may pick any
  19       number less than 4294967295. In the case that sequential number are set
  20       automatically, the sequential number will increase by a unit of five (5)
  21       per list. If a list with no specified sequential number is created
  22       after a list with a specified sequential number, the list will
  23       automatically pick the next multiple of five (5) as the list number.
  24       For example, if a list with number 2 already exists and a new list with
  25       no specified number is created, the next list will be numbered 5. If
  26       lists 2 and 7 already exist and a new list with no specified number is
  27       created, the new list will be numbered 10.
  28
  29    Basic filtering is done by `access-list` as shown in the
  30    following example.
  31
  32    .. code-block:: frr
  33
  34       access-list filter deny 10.0.0.0/9
  35       access-list filter permit 10.0.0.0/8
  36       access-list filter seq 13 permit 10.0.0.0/7
  37
  38
  39 IP Prefix List
  40 ==============
  41
  42 *ip prefix-list* provides the most powerful prefix based
  43 filtering mechanism. In addition to *access-list* functionality,
  44 *ip prefix-list* has prefix length range specification and
  45 sequential number specification. You can add or delete prefix based
  46 filters to arbitrary points of prefix-list using sequential number specification.
  47
  48 If no ip prefix-list is specified, it acts as permit. If *ip prefix-list*
  49 is defined, and no match is found, default deny is applied.
  50
  51 .. clicmd:: ip prefix-list NAME (permit|deny) PREFIX [le LEN] [ge LEN]
  52
  53 .. clicmd:: ip prefix-list NAME seq NUMBER (permit|deny) PREFIX [le LEN] [ge LEN]
  54
  55    You can create *ip prefix-list* using above commands.
  56
  57    seq
  58       seq `number` can be set either automatically or manually. In the
  59       case that sequential numbers are set manually, the user may pick any
  60       number less than 4294967295. In the case that sequential number are set
  61       automatically, the sequential number will increase by a unit of five (5)
  62       per list. If a list with no specified sequential number is created
  63       after a list with a specified sequential number, the list will
  64       automatically pick the next multiple of five (5) as the list number.
  65       For example, if a list with number 2 already exists and a new list with
  66       no specified number is created, the next list will be numbered 5. If
  67       lists 2 and 7 already exist and a new list with no specified number is
  68       created, the new list will be numbered 10.
  69
  70    le
  71       Specifies prefix length. The prefix list will be applied if the prefix
  72       length is less than or equal to the le prefix length.
  73
  74    ge
  75       Specifies prefix length. The prefix list will be applied if the prefix
  76       length is greater than or equal to the ge prefix length.
  77
  78
  79    Less than or equal to prefix numbers and greater than or equal to
  80    prefix numbers can be used together. The order of the le and ge
  81    commands does not matter.
  82
  83    If a prefix list with a different sequential number but with the exact
  84    same rules as a previous list is created, an error will result.
  85    However, in the case that the sequential number and the rules are
  86    exactly similar, no error will result.
  87
  88    If a list with the same sequential number as a previous list is created,
  89    the new list will overwrite the old list.
  90
  91    Matching of IP Prefix is performed from the smaller sequential number to the
  92    larger. The matching will stop once any rule has been applied.
  93
  94    In the case of no le or ge command, the prefix length must match exactly the
  95    length specified in the prefix list.
  96
  97
  98 .. _ip-prefix-list-description:
  99
 100 ip prefix-list description
 101 --------------------------
 102
 103 .. clicmd:: ip prefix-list NAME description DESC
 104
 105    Descriptions may be added to prefix lists. This command adds a
 106    description to the prefix list.
 107
 108
 109 .. _showing-ip-prefix-list:
 110
 111 Showing ip prefix-list
 112 ----------------------
 113
 114 .. clicmd:: show ip prefix-list
 115
 116    Display all IP prefix lists.
 117
 118 .. clicmd:: show ip prefix-list NAME
 119
 120    Show IP prefix list can be used with a prefix list name.
 121
 122 .. clicmd:: show ip prefix-list NAME seq NUM
 123
 124    Show IP prefix list can be used with a prefix list name and sequential
 125    number.
 126
 127 .. clicmd:: show ip prefix-list NAME A.B.C.D/M
 128
 129    If the command longer is used, all prefix lists with prefix lengths equal to
 130    or longer than the specified length will be displayed. If the command first
 131    match is used, the first prefix length match will be displayed.
 132
 133 .. clicmd:: show ip prefix-list NAME A.B.C.D/M longer
 134 .. clicmd:: show ip prefix-list NAME A.B.C.D/M first-match
 135 .. clicmd:: show ip prefix-list summary
 136 .. clicmd:: show ip prefix-list summary NAME
 137 .. clicmd:: show ip prefix-list detail
 138 .. clicmd:: show ip prefix-list detail NAME
 139
 140 Clear counter of ip prefix-list
 141 -------------------------------
 142
 143 .. clicmd:: clear ip prefix-list [NAME [A.B.C.D/M]]
 144
 145    Clears the counters of all IP prefix lists. Clear IP Prefix List can be used
 146    with a specified NAME or NAME and prefix.