3Com 7700 Configuration Manual page 134

126 C 5: R P
HAPTER OUTING
O
ROTOCOL PERATION
By default, the MED metric is 0.
Comparing the MED Routing Metrics from the Peers in Different ASs
This comparison is used to select the best route. The route with smaller MED value
will be selected.
Perform the following configurations in BGP view.
Table 106 Comparing the MED Routing Metrics from the Peers in Different ASs
Operation
Comparing the MED Routing Metrics from the
Peers in Different ASs
Configure not to compare the MED routing
metrics from the peers in different ASs
By default, MED comparison is not allowed among the routes from the neighbors
in different ASs.
It is not recommended to use this configuration unless you can make sure that the
ASs adopt the same IGP and routing method.
Configuring a BGP Community
Community attributes are optional and transitive. Some community attributes are
globally recognized, which are called standard community attributes, whereas
some are for special purposes which are called extended community attributes.
You may define not only the standard community but also the extended
community attributes.
Community-list is used to identify a community, which falls into standard
community-list and extended community-list.
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 configurations in system view.
Table 107 Configuring a BGP Community
Operation
Configure a standard community list
Configure an extended community list
Remove the configured community list
By default, no BGP community is configured.
Command
compare-different-as-med
undo compare-different-as-med
Command
ip community-list standard-community-list-number {
permit | deny } { aa:nn | internet |
no-export-subconfed | no-advertise | no-export }
ip community-list extended-community-list-number {
permit | deny } as-regular-expression
undo ip community-list {
standard-community-list-number |
extended-community-list-number }