PLANET XGS3-24042 - Manual (Page 475)

31-114
31.2 ip prefix-list seq
Command:
ip prefix-list <list_name> [seq <sequence_number>] < any |
ip_addr/mask_length [ge <min_prefix_len>] [le <max_prefix_len>]>
no ip prefix-list <list_name> [seq <sequence_number>] [ < any |
ip_addr/mask_length [ge <min_prefix_len>] [le <max_prefix_len>]>]
Function:
Configure the prefix-list. The “no ip prefix-list <list_name> [seq <sequence_number>] [
permit> < any | ip_addr/mask_length [ge <min_prefix_len>] [le <max_prefix_len>]>]”
command deletes the prefix-list.
Parameter:
is the name of prefix-list, “seq” shows the following parameters is the sequence
number, <sequence_number> is the sequence number, “deny” means deny this route, “permit”
means permit this route, “any” means adaptive to all packets with any prefix as well as any mask
length, ip_addr/mask_length shows the prefix address (dotted decimal notation) and the length of
mask, “ge” means greater than or equal to, <min_prefix_len> is the minimum length of prefix to be
matched (ranging between 0～32), “le” means less than or equal to, <max_prefix_len> is the
maximum length of prefix to be matched (ranging between 0～32).
Command Mode:
Global Mode
Usage Guide:
A prefix-list is identified by a prefix-list name. Each prefix-list may include several items each of
which independently specifies a matching scope of network prefix-list type which is identified with a
sequence-number. sequence-number specifies the sequence of matching check in the prefix-list. In
the matching process the switch check in turn every items identified by “sequence-number”
ascending. Once certain item obtains the conditions then the prefix-list filter is passed (without
proceeding into the next item check)
Attentions should be paid on that at least one item match mode should be “permit” when more than
one prefix-list items is defined. The deny mode items can be previously defined so to remove the
unsuitable routing messages fast. However if all items are at deny mode then none of the routes
would be able to pass the filter of this prefix-list. We here can define a “permit 0.0.0.0/0 ge 0 le 32”
item after several defined “deny mode” items so to grant the passage for all other routing messages.
Example:
Switch#config terminal
Switch(config)#ip prefix-list mylist seq 12345 deny 10.0.0.0/8 le 22 ge 14