Filtering

• Command: access-list NAME permit IPV4-NETWORK
  Command: access-list NAME deny IPV4-NETWORK
  

  Basic filtering is done by `access-list' as shown in the following example.

       access-list filter deny 10.0.0.0/9
       access-list filter permit 10.0.0.0/8
  

ip prefix-list provides the most powerful prefix based filtering mechanism. adding to access-list functionality, ip prefix-list has prefix length range specification and sequential number specification. you can add or delete prefix based filter to arbitrary point of prefix-list using sequential number.

If no ip prefix-list is specified, it acts as permit. Once ip prefix-list is defined, then no match is performed, default deny is applied.

• Command: ip prefix-list NAME (permit|deny) PREFIX [le LEN] [ge LEN]
  Command: ip prefix-list NAME seq NUMBER (permit|deny) [le LEN] [ge LEN]
  You can create ip prefix-list using above commands.
  

  seq	seq NUMBER can be set either automatically or manually. In the case that sequential numbers are set manually, the user may pick any number less than 4294967295. In the case that sequential number are set automatically, the sequential number will increase by a unit of five (5) per list. If a list with no specified sequential number is created after a list with a specified sequential number, the list will automatically pick the next multiple of five (5) as the list number. For example, if a list with number 2 already exists and a new list with no specified number is created, the next list will be numbered 5. If lists 2 and 7 already exist and a new list with no specified number is created, the new list will be numbered 10.
  le	le command specify prefix length. If the given prefix length is lesser than or equal to le prefix length. Prefix Lists can be applied on the basis of prefix length. The le command specifies prefix length. The prefix list will be applied if the prefix length is lesser than or equal to the le prefix length.
  ge	ge command specify prefix length. If the given prefix length is lesser than or equal to ge prefix length. The ge command specifies prefix length. The prefix list will be applied if the prefix length is greater than or equal to the ge prefix length.

  Lesser than or equal to prefix numbers and greater than or equal to prefix numbers can be used together. The order of the le and ge commands does not matter.

  If a prefix list with a different sequential number but with the exact same rules as a previous list is created, an error will result. However, in the case that the sequential number and the rules are exactly similar, no error will result.

  If a list with the same sequential number as a previous list is created, the new list will overwrite the old list.

  Matching of IP Prefix is performed from the smaller sequential number to the larger. The matching will stop once any rule has been applied.

  In the case of no le or ge command,

  Version 0.85: the matching rule will apply to all prefix lengths that matched the prefix list.

  Version 0.86 or later: In the case of no le or ge command, the prefix length must match exactly the length specified in the prefix list.

• Command: no ip prefix-list NAME

  Menu
  ip prefix-list description
  ip prefix-list sequential number control
  Showing ip prefix-list
  Clear counter of ip prefix-list

ip prefix-list description

• Command: ip prefix-list NAME descrtiption DESC
  Description may be added to prefix lists. This command adds a description to the prefix list.

• Command: no ip prefix-list NAME descrtiption DESC
  Deletes the description from a prefix list. It is possible to use the command without the full description.

ip prefix-list sequential number control

• Command: ip prefix-list sequence-number
  With this command the IP prefix list sequential number is displayed. This is the default behavior.

• Command: no ip prefix-list sequence-number
  With this command, the IP oprefix list sequential number is not displayed.

Showing ip prefix-list

• Command: show ip prefix-list
  Display all IP prefix lists.

• Command: show ip prefix-list NAME
  Show IP prefix list can be used with a prefix list name.

• Command: show ip prefix-list NAME seq NUM
  Show IP prefix list can be used with a prefix list name and sequential number.

• Command: show ip prefix-list NAME A.B.C.D/M
  If the command longer is used, all prefix lists with prefix lengths equal to or longer than the specified length will be displayed. If the command first match is used, the first prefix length match will be displayed.

• Command: show ip prefix-list NAME A.B.C.D/M longer

• Command: show ip prefix-list NAME A.B.C.D/M fisrt-match

• Command: show ip prefix-list summary

• Command: show ip prefix-list summary NAME

• Command: show ip prefix-list detail

• Command: show ip prefix-list detail NAME

Clear counter of ip prefix-list

• Command: clear ip prefix-list
  Clears the counters of all IP prefix lists. Clear IP Prefix List can be used with a specified name and prefix.

• Command: clear ip prefix-list NAME

• Command: clear ip prefix-list NAME A.B.C.D/M

IP Community List

• Command: ip community-list NAME TYPE COMMUNITY

• Command: ip as-path access-list NAME TYPE AS_PATH

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