Huawei Quidway NetEngine80E Configuration Manual page 927

HUAWEI NetEngine80E/40E Router
Configuration Guide - IP Routing
The preceding command output shows that both * and > are in front of the route 3.3.3.9/32,
which indicates that the route is valid and optimal.
PrefVal
BGP prefers the route with the largest PreVal value during BGP route selection.
PrefVal is Huawei-specific and valid only on the device where it is configured. The PreVal
attribute is set by customers. Therefore, BGP first compares the PreVal values during route
selection.
To configure a PreVal value for the routes learned from a peer or peer group, run the peer
{ group-name | ipv4-address } preferred-value value command.
If multiple routes are available to the same destination, the route with the largest PreVal value
is selected as the optimal route. By default, the PreVal of the routes learned from BGP peers is
0.
Table 8-16
Table 8-16 Methods to modify the PreVal value
Method
Run the peer { group-name | ipv4-address }
preferred-value value command.
Configure an import policy and run the apply
preferred-value preferred-value command
to configure an apply clause for the policy.
The following example shows how the PreVal value is used during route selection. In
8-13, both ISP1 and ISP2 advertise the routes 10.11.0.0/16 and 10.22.0.0/16 to AS 65001.
Issue 02 (2014-09-30)
lists two methods to modify the PreVal value.
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Copyright © Huawei Technologies Co., Ltd.
Usage Scenario
This method sets a PreVal value for the routes
learned from a peer or peer group.
This method sets different PreVal values for
different routes learned from a peer or peer
group.
NOTE
If both the methods are used, the method with the
import policy takes effect if routes match the
conditions specified in the peer preferred-value
command and the import policy.
8 BGP Configuration
Figure
902