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+@node Filtering
+@comment  node-name,  next,  previous,  up
+@chapter Filtering
+
+Zebra provides many very flexible filtering features.  Filtering is used
+for both input and output of the routing information.  Once filtering is
+defined, it can be applied in any direction.
+
+@menu
+* IP Access List::              
+* IP Prefix List::              
+@end menu
+
+@node IP Access List, IP Prefix List, Filtering, Filtering
+@comment  node-name,  next,  previous,  up
+@subsection IP Access List
+
+@deffn {Command} {access-list @var{name} permit @var{ipv4-network}} {}
+@deffnx {Command} {access-list @var{name} deny @var{ipv4-network}} {}
+@end deffn
+
+Basic filtering is done by @code{access-list} as shown in the
+following example.
+
+@example
+access-list filter deny 10.0.0.0/9
+access-list filter permit 10.0.0.0/8
+@end example
+
+@node IP Prefix List,  , IP Access List, Filtering
+@comment  node-name,  next,  previous,  up
+@subsection IP Prefix List
+
+@command{ip prefix-list} provides the most powerful prefix based
+filtering mechanism.  In addition to @command{access-list} functionality,
+@command{ip prefix-list} has prefix length range specification and
+sequential number specification.  You can add or delete prefix based
+filters to arbitrary points of prefix-list using sequential number specification.
+
+If no ip prefix-list is specified, it acts as permit.  If @command{ip prefix-list} 
+is defined, and no match is found, default deny is applied.
+
+@c @deffn {Command} {ip prefix-list @var{name} [seq @var{number}] permit|deny [le @var{prefixlen}] [ge @var{prefixlen}]} {}
+@deffn {Command} {ip prefix-list @var{name} (permit|deny) @var{prefix} [le @var{len}] [ge @var{len}]} {}
+@deffnx {Command} {ip prefix-list @var{name} seq @var{number} (permit|deny) @var{prefix} [le @var{len}] [ge @var{len}]} {}
+
+You can create @command{ip prefix-list} using above commands.
+
+@table @asis
+
+@item @asis{seq}
+seq @var{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.
+
+@item @asis{le}
+@command{le} command specifies prefix length.  The prefix list will be 
+applied if the prefix length is less than or equal to the le prefix length.
+
+@item @asis{ge}
+@command{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.
+
+@end table
+
+@end deffn
+
+Less 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.
+
+
+@deffn {Command} {no ip prefix-list @var{name}} {}
+@end deffn
+
+@menu
+* ip prefix-list description::  
+* ip prefix-list sequential number control::  
+* Showing ip prefix-list::      
+* Clear counter of ip prefix-list::  
+@end menu
+
+@node ip prefix-list description, ip prefix-list sequential number control, IP Prefix List, IP Prefix List
+@comment  node-name,  next,  previous,  up
+@subsubsection ip prefix-list description
+
+@deffn {Command} {ip prefix-list @var{name} description @var{desc}} {}
+Descriptions may be added to prefix lists.  This command adds a
+description to the prefix list.
+@end deffn
+
+@deffn {Command} {no ip prefix-list @var{name} description [@var{desc}]} {}
+Deletes the description from a prefix list.  It is possible to use the
+command without the full description.
+@end deffn
+
+@node  ip prefix-list sequential number control, Showing ip prefix-list, ip prefix-list description, IP Prefix List
+@comment  node-name,  next,  previous,  up
+@subsubsection ip prefix-list sequential number control
+
+@deffn {Command} {ip prefix-list sequence-number} {}
+With this command, the IP prefix list sequential number is displayed.
+This is the default behavior.
+@end deffn
+
+@deffn {Command} {no ip prefix-list sequence-number} {}
+With this command, the IP prefix list sequential number is not
+displayed.
+@end deffn
+
+@node  Showing ip prefix-list, Clear counter of ip prefix-list, ip prefix-list sequential number control, IP Prefix List
+@comment  node-name,  next,  previous,  up
+@subsubsection Showing ip prefix-list
+
+@deffn {Command} {show ip prefix-list} {}
+Display all IP prefix lists.
+@end deffn
+
+@deffn {Command} {show ip prefix-list @var{name}} {}
+Show IP prefix list can be used with a prefix list name.
+@end deffn
+
+@deffn {Command} {show ip prefix-list @var{name} seq @var{num}} {}
+Show IP prefix list can be used with a prefix list name and sequential
+number.
+@end deffn
+
+@deffn {Command} {show ip prefix-list @var{name} @var{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.
+@end deffn
+
+@deffn {Command} {show ip prefix-list @var{name} @var{a.b.c.d/m} longer} {}
+@end deffn
+
+@deffn {Command} {show ip prefix-list @var{name} @var{a.b.c.d/m} first-match} {}
+@end deffn
+
+@deffn {Command} {show ip prefix-list summary} {}
+@end deffn
+@deffn {Command} {show ip prefix-list summary @var{name}} {}
+@end deffn
+
+@deffn {Command} {show ip prefix-list detail} {}
+@end deffn
+@deffn {Command} {show ip prefix-list detail @var{name}} {}
+@end deffn
+
+@node  Clear counter of ip prefix-list,  , Showing ip prefix-list, IP Prefix List
+@comment  node-name,  next,  previous,  up
+@subsubsection Clear counter of ip prefix-list
+
+@deffn {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.
+@end deffn
+
+@deffn {Command} {clear ip prefix-list @var{name}} {}
+@end deffn
+
+@deffn {Command} {clear ip prefix-list @var{name} @var{a.b.c.d/m}} {}
+@end deffn
+