Brocade Multi-Service IronWare Routing Configuration Guide (Supporting R05.6.00) - Manual (Page 233)

Multi-Service IronWare Routing Configuration Guide 205
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Adding additional parameters
Defining and applying IP prefix lists
An IP prefix list specifies a list of networks. When you apply an IP prefix list to an area, the Brocade
device sends or receives only a route whose destination is in the IP prefix list. The software
interprets the prefix lists in order, beginning with the lowest sequence number.
To configure an IP prefix list and apply it to an area, enter commands such as the following.
Brocade(config)# ip prefix-list Routesfor20 permit 20.20.0.0/24
Brocade(config)# router ospf
Brocade(config-ospf-router)#)# area 10.10.10.1 prefix-list Routesfor20 out
These commands configure an IP prefix list named Routesfor20, which permits routes to network
20.20.0.0/24. The area command configures the device to use IP prefix list Routesfor20 to
determine which routes to send to area 10.10.10.1. The device sends routes that go to 20.20.x.x to
area 10.10.10.1 because the IP prefix list explicitly permits these routes to be sent to the area.
Syntax: ip prefix-list name [seq seq-value] [description string] {deny | permit}
network-addr/mask-bits [ge ge-value] [le le-value]
The name variable specifies the prefix list name. You use this name when applying the prefix list to
a neighbor.
The seq seq-value parameter is optional and specifies the IP prefix list’s sequence number. If you
do not specify a sequence number, the software numbers them in increments of 5, beginning with
prefix list entry 5. The software interprets the prefix list entries in numerical order, beginning with
the lowest sequence number.
The description string parameter is a text string describing the prefix list.
The deny | permit parameter specifies the action the software takes if a neighbor’s route is in this
prefix list.
The prefix-list matches only on this network unless you use the ge ge-value or le le-value
parameters. (See below.)
The network-addr/mask-bits variable specifies the network number and the number of bits in the
network mask.
You can specify a range of prefix length for prefixes that are more specific than
network-addr/mask-bits.
• If you specify only ge ge-value, then the mask-length range is from ge-value to 32.
• If you specify only le le-value, then the mask-length range is from length to le-value.
• The ge-value or le-value you specify must meet the following condition.
length <ge-value <= le-value <= 32
If you do not specify ge ge-value or le le-value, the prefix list matches only on the exact network
prefix you specify with the network-addr/mask-bits parameter.
Displaying the configured OSPF area prefix list
To display the prefix-lists attached to the areas, enter the following command.