3Com 8807 Configuration Manual page 398

398 C 34: IP R
HAPTER OUTING
Configuring ip-prefix
Configuring the AS Path
P C
OLICY ONFIGURATION
By default, perform no settings.
Note that if the routing information meets the match conditions specified in the
route-policy and also notifies the MED value configured with the apply cost-type
internal when notifying the IGP route to the EBGP peers, then this value will be
regarded as the MED value of the IGP route. The preference configured with the
apply cost-type internal command is lower than that configured with the apply
cost command, but higher than that configured with the default med command.
An IP-prefix-list is identified by an ip-prefix-name. Each IP-prefix-list can include
multiple entries each specifying an IP prefix matching range. IP prefix entries are
identified by index-numbers. 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 396 Define prefix-list
Operation
Define prefix-list
Remove 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 (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 defined first 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.
The routing information packet of the BGP includes an autonomous system path
List 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 397 Define the AS path list
Operation
Define the AS path list
Delete the specified AS path list
By default, no AS path list is defined.
Command
ip ip-prefix ip-prefix-name [ index index-number ] { permit | deny }
network len [ greater-equal greater-equal ] [ less-equal less-equal ]
undo ip ip-prefix ip-prefix-name [ index index-number | permit |
deny ]
Command
ip as-path-acl acl-number { permit | deny }
as-regular-expression
undo ip as-path-acl acl-number