3Com 3C13636 Configuration Manual page 710

3Com Router 3000 Ethernet Family
Configuration Guide
During the matching, the router checks list items identified by the index-number in the
ascending order. If any one list item meets the condition, it means that it has passed the
ip-prefix filtering (will not enter the testing of the next list item).
Pay attention to the following:
If more than one ip-prefix item are 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 firstly defined to rapidly filter the routing
information not satisfying the requirement, but if all the items are in the deny mode,
any routes will not 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 so as to let all the other routes pass.
For instance, the following configuration will filter out routes from segments 10.1.0.0,
10.2.0.0, and 10.3.0.0, while allowing routing information from other segments to pass
through.
[Router] ip ip-prefix 1 deny 10.1.0.0 16
[Router] ip ip-prefix 2 deny 10.2.0.0 16
[Router] ip ip-prefix 3 deny 10.3.0.0 16
[Router] ip ip-prefix 4 permit 0.0.0.0/0 greater-equal 0 less-equal 32
2) Defining ACL
Refer to the part related to security.
II. Configuring to filter received routes
Perform the following configuration in routing protocol view.
Define a policy rule to filter unqualified routing information during route reception by
redistributing an ACL or IP-prefix. The keyword parameter gateway indicates only
update packets from specific peer routers will be received.
Table 7-2 Configure to filter the redistributed routes
Configure to filter the received routing
information redistributed by the specified
address
Cancel the filtering of the received
routing information redistributed by the
specified address
Configure to filter the received global
routing information
Cancel the filtering of the received
routing information
Operation
3Com Corporation
7-4
Chapter 7 IP Routing Policy Configuration
Command
filter-policy gateway ip-prefix-name
import
undo filter-policy
ip-prefix-name import
filter-policy { acl-number | ip-prefix
ip-prefix-name } [ gateway ] import
undo filter-policy
ip-prefix ip-prefix-name } [ gateway ]
import
gateway
{ acl-number |