3Com 7700 Configuration Manual page 133

Perform the following configurations in BGP view.
Table 103 Configuring a BGP Timer
Operation
Configure BGP Timer
Restore the default value of the timer
By default, the interval of sending keepalive packet is 60 seconds. The interval of
sending holdtime packet is 180 seconds.
Configuring the Local Preference
Different local preferences can be configured to affect the BGP routing. When a
router running BGP gets routes with the same destination address but different
next hops through different internal peers, it will select the route of the highest
local preference.
Perform the following configurations in BGP view.
Table 104 Configuring the Local Preference
Operation
Configure the local preference
Restore the default local preference
The local preference is transmitted only when the IBGP peers exchange the update
packets and it will not be transmitted beyond the local AS.
By default, the local preference is 100.
Configuring MED for AS
Multi-Exit Discriminators (MED) attribute is the external metric for a route. It is
exchanged between ASs. However, it will not be transmitted beyond an AS once it
is imported into the AS.
AS uses the local preference to select the route to the outside and MED to
determine the optimum route for entering the AS. When a router running BGP
gets routes with the same destination address but different next hops through
different external peers, it will select the route of the smallest MED as the
optimum route, provided that all the other conditions are the same.
Perform the following configurations in BGP view.
Table 105 Configuring MED for AS
Operation
Configure an MED metric for the system
Restore the default MED metric of the system undo default med
The router configured above only compares the route MED metrics of different
EBGP peers in the same AS. Using the compare-different-as-med command,
you can compare the route MED metrics of the peers in different ASs.
Command
peer { group-name | peer-address } timer
keep-alive keepalive-interval hold
holdtime-interval
undo peer { group-name | peer-address } timer
Command
default local-preference value
undo default local-preference
Command
default med med-value
BGP 125