3Com Switch 8800 Configuration Guide
Chapter 22 IP Routing Policy Configuration
22-7
22.2.2 Configuring ip-prefix
z
A prefix-list is identified by an
ip
-
prefix
-
name
. Each IP prefix-list may include
multiple entries each specifying an IP prefix matching range. IP prefix entries are
identified by
index
-
number
s. The order in which IP prefix entries are matched
against depends on the order of their index numbers.
Perform the following configuration in system view.
Table 22-4
Define prefix-list
Operation
Command
Define prefix-list
ip ip-prefix
ip
-
prefix
-
name
[
index
index
-
number
] {
permit
|
deny
}
network
len
[
greater-equal
greater
-
equal
]
[
less-equal
less
-
equal
]
Remove prefix-list
undo ip ip-prefix
ip
-
prefix
-
name
[
index
index
-
number
|
permit
|
deny
]
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 (will not enter the testing of the next list item).
Note that 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, 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 so as to let all the other routes pass.
22.2.3 Configuring the AS Path List
The routing information packet of the BGP includes an autonomous system path
domain. The as path-list can be used to match with the autonomous system path
domain of the BGP routing information so as to filter the routing information, which does
not conform to the requirements.
Perform the following configuration in the system view:
Table 22-5
Define the AS path list
Operation
Command
Define the AS path list
ip as-path-acl
acl
-
number
{
permit
|
deny
}
as
-
regular
-
expression
Delete the specified AS path list
undo ip as-path-acl
acl
-
number
By default, no AS path list is defined.
