3com 3031 Instruccion De Instalación

from different external peers, it will opt for the one with smaller MED value as its 
optimal route in the AS under the premise that other conditions are the same.

Perform the following configurations in BGP view.

The router configured above only compares the route MED value of different EBGP 
peers in the same AS. Using the 

 command, you can 

compare the route MED metrics of the peers in different ASs.

By default, MED value is 0.

It is used to select the optimal route. When other conditions are the same, the 
route with smaller MED will be selected as the external route in an AS.

Perform the following configurations in BGP view.

By default, MED comparison is not allowed among the routes from the peers in 
different ASs.

You are not recommended to use this configuration unless you can make sure that 
the ASs adopt the same IGP and routing method.

Community is an optional transitional attribute. Some community attributes are 
globally-accepted, called as standard community attributes; others are used for 
special purposes. The user can define extended community attributes.

Community list, including standard-community-list and extended-community-list, 
is a list identifying information of a community.

In addition, a route can have more than one community attributes. In a route, the 
speaker of multiple community attributes can act according to one, several or all 
the attributes. Router can choose to change the community attribute or leave it 
unchanged before transmitting the route to its peers.

Perform the following in the System View.

Table 651   Configuring an MED for the system

Configure a MED for the system

Restore the default MED of the system

Table 652   Comparing MED routing costs from the peers in different ASs

Compare MED routing costs from the peers in 
different ASs

Disable the comparison of MED routing costs from 
the peers in different ASs

Table 653   Configuring community attribute