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IP Access Control Lists (ACL), Prefix Lists, and Route-maps | 155
If you are creating a standard prefix list with only one or two filters, you can let FTOS assign a sequence
number based on the order in which the filters are configured. The FTOS assigns filters in multiples of
five.
To configure a filter without a specified sequence number, use these commands in the following sequence
starting in the CONFIGURATION mode:
Figure 8-14 illustrates a prefix list in which the sequence numbers were assigned by the software. The
filters were assigned sequence numbers based on the order in which they were configured (for example,
the first filter was given the lowest sequence number). The
show config command in the PREFIX LIST
mode displays the two filters with the sequence numbers 5 and 10.
Figure 8-14. Prefix List
To delete a filter, enter the show config command in the PREFIX LIST mode and locate the sequence
number of the filter you want to delete; then use the
no seq sequence-number command in the PREFIX
LIST mode.
To view all configured prefix lists, use either of the following commands in the EXEC mode:
Step Command Syntax Command Mode Purpose
1
ip prefix-list prefix-name CONFIGURATION Create a prefix list and assign it a unique
name.
2
{deny | permit} ip-prefix [ge
min-prefix-length] [le
max-prefix-length]
CONFIG-NPREFIXL Create a prefix list filter with a deny or
permit action. The optional parameters are:
•
ge min-prefix-length: is the minimum
prefix length to be matched (0 to 32).
•
le max-prefix-length: is the maximum
prefix length to be matched (0 to 32).
Command Syntax Command Mode Purpose
show ip prefix-list detail [prefix-name]
EXEC Privilege Show detailed information about configured Prefix
lists.
show ip prefix-list summary
[prefix-name]
EXEC Privilege Show a table of summarized information about
configured Prefix lists.
FTOS(conf-nprefixl)#permit 123.23.0.0 /16
FTOS(conf-nprefixl)#deny 133.24.56.0 /8
FTOS(conf-nprefixl)#show conf
!
ip prefix-list awe
seq 5 permit 123.23.0.0/16
seq 10 deny 133.0.0.0/8
FTOS(conf-nprefixl)#