3Com Switch 7700 Configuration Manual page 188

180 C 5: IP R
HAPTER OUTING
P O
ROTOCOL PERATION
Table 136 Defining Prefix-list
Operation
Remove a prefix list
During the matching, the router checks list items identified by the index-number in
the ascending order. If only one list item meets the condition, it means that it has
passed the ip-prefix filtering (and does not enter the testing of the next list item).
If more than one IP prefix item is defined, then the match mode of at least one list
item should be the permit mode. The list items of the deny mode can be defined
to rapidly filter the routing information not satisfying the requirement, but if all
the items are in the deny mode, no route will pass the ip-prefix filtering. You can
define an item of permit 0.0.0.0/0 greater-equal 0 less-equal 32 after the
multiple list items in the deny mode to let all the other routes pass.
Configuring for Filtering Received Routes
Perform the following configuration in routing protocol view.
Define a policy that filters the routing information that does not satisfy the
conditions and receives routes with the help of an ACL or address prefix-list. The
filter-policy gateway command specifies that only the update packets from a
specific neighboring router will be received.
Table 137 Configuring Filtering for Received Routes
Operation
Configure to filter the received routing
information distributed by the specified
address
Cancel the filtering of the received routing
information distributed by the specified
address
Configure to filter the received global routing
information
Cancel the filtering of the received global
routing information
Configuring for Filtering Distributed Routes
Define a policy concerning route distribution that filters the routing information
that does not satisfy the conditions, and distributes routes with the help of an ACL
or address ip-prefix.
Perform the following configuration in routing protocol view.
Table 138 Configuring Filtering of Distributed Routes
Operation
Configure to filter the routes distributed by
the protocol
Cancel the filtering of the routes distributed
by the protocol
Command
undo ip ip-prefix ip-prefix-name [ index
index-number | permit | deny ]
Command
filter-policy gateway ip-prefix-name import
undo filter-policy gateway ip-prefix-name
import
filter-policy { acl-number | ip-prefix
ip-prefix-name } [ gateway ] import
undo filter-policy { acl-number | ip-prefix
ip-prefix-name } [ gateway ] import
Command
filter-policy { acl-number | ip-prefix
ip-prefix-name } export [ routing-process ]
undo filter-policy { acl-number | ip-prefix
ip-prefix-name } export [ routing-process ]