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ip prefix-list
Creates/deletes a prefix-based access list.
Syntax: ip prefix-list listName [description listDescription] [seq seqNum] [{permit | deny} prefix&mask] [[ge geVal] [le leVal]]
no ip prefix-list listName
listName
The name of the prefix list being configured. Valid values are up to 256 alpha numeric characters as well as dashes, underscores, and commas.
listDescription
A user defined description of the prefix list. Valid values are up to 256 alpha numeric characters and may include dashes, underscores, and commas.
seqNum
A numeric value specifying the order of prefix lookup for this list. Default is highest already configured sequence value plus 5.
prefix&mask
The prefix and mask to be applied to this list.
geVal
The greater-than-or-equal-to value of the mask length to be applied to this prefix. Valid values are 1 - 32.
leVal
The less-than-or-equal-to value of the mask length to be applied to this prefix. Valid values are 1 - 32.
Use the ip prefix-list listName description command to specify a description that further identifies this prefix list.
Use the ip prefix-list listName permit command along with a prefix and mask to identify the prefixes that will be permitted for update.
Use the ip prefix-list listName deny command along with a prefix and mask to identify the prefixes that will be denied for update.
Use the ip prefix-list listName {permit | deny} seq command to specify lookup order for this prefix and mask relative to other entries for this prefix list.
Use the ge keyword to specify a greater-than-or-equal-to mask length value to apply to this prefix list entry. If you specify 24, only prefixes that fall within the 24 and 32 bit range will apply to this entry. This keyword can be used alone or with the le keyword.
Use the le keyword to specify a less-than-or-equal-to mask length value to apply to this prefix list entry. If you specify 24 for le and 16 for ge, only prefixes that fall within the 16 and 24 bit mask range will apply to this entry.
Example: The following example builds a prefix list named boston-ny and associates the Boston-NY_Priority description with it:
- The first list input names the prefix list boston-ny and permits prefix filtering of updates for 10.10.10.0/24. The sequence number defaults to 5 because it is the first entry and the sequence number is not specified in the command line. Prefixes permitted by this line would be values 10.10.10. 0 through 255.
- The second prefix list entry associates the description Boston-NY_Priority with the boston-ny list.
- The next prefix list entry permits prefix filtering of updates for 20.20.20.0/16 and assigns a sequence number of 6 to this prefix entry. Prefixes permitted by this line would be values 20.20.0 through 255.0 through 255.
- The next prefix list entry permits prefix filtering of updates for 30.30.0.0/16 for all prefixes of length greater-than-or-equal-to 25. The sequence number for this entry defaults to 11 because the previous highest listing is 6, and the command line does not specify a sequence number. Prefixes permitted by this line would be values 30.30.0.0 through 255
- The final prefix list entry permits prefix filtering of updates for 40.40.40.0/24 for all prefixes of length greater-than-or-equal-to 26 and less-than-or-equal-to 30. The sequence number for this entry defaults to 16 because the previous highest listing is 11, and the command line does not specify a sequence number. Prefixes permitted by this line would be values 40.40.40.4 through 127
- The show ip prefix-list command in privileged mode, displays configuration details for this Avici router per configured list.
router#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
router(config)#ip prefix-list boston-ny permit 10.10.10.0/24
router(config)#ip prefix-list boston-ny description Boston-NY_Priority
router(config)#ip prefix-list boston-ny seq 6 permit 20.20.20.0/16
router(config)#ip prefix-list boston-ny permit 30.30.0.0/16 ge 25
router(config)#ip prefix-list boston-ny permit 40.40.40.0/24 ge 26 le 30
router(config)#end
router#show ip prefix-list
SEQUENCED IP prefix list boston-ny description Boston-NY_Priority
seq 5 permit 10.10.10.0/24
seq 6 permit 20.20.20.0/16
seq 11 permit 30.30.0.0/16 ge 25
seq 16 permit 40.40.40.0/24 ge 26 le 30
Related Commands: show ip prefix-list
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Copyright © 2004
Avici Systems Inc.
Avici® and TSR®
is a registered trademark of Avici Systems Inc.
IPriori™, Composite Links™, SSR™, QSR, and NSR® are
trademarks of Avici Systems Inc.
Source
File Name: Routing_Pol.fm
HTML File Name: Routing_Pol18.html
Last Updated: 05/10/04 at 16:38:37