3Com 10014299 manual Configure the Local Preference, Timers keepalive-interval, Holdtime-interval

	Configuring BGP 455
Allow comparing path MED	compare-different-as-med
Prohibit comparing path MED	undo compare-different-as-med

By default, MED values from different AS neighboring routes are not compared when determining the best route.

This configuration should not be used unless it is certain that different ASs uses the same IGP and routing modes.

Configuring the Local Configuring different local preferences affects BGP routing selection. When a Preference router running BGP gets routes with the same destination address but different

next hops through different internal peers, it selects the route of the highest local preference to this destination.

Perform the following configurations in BGP view.

Table 524 Configure the Local Preference

Operation	Command
Configure the local preference	default local-preference value
Restore the local preference value to its	undo default local-preference
default value

By default, the value of local preference is 100.

Configuring BGP Timers The interval of sending keepalive messages required by RFC and BGP holdtime are important parameters in BGP protocol.

When a router has created a BGP connection successfully with the other router, it sends keepalive messages to this router with the time interval set by the keepalive-intervalattribute to indicate whether the connection channel is normal. Generally, the time interval for sending a keepalive message is one third of the value for the holdtime attribute.

The value of the holdtime-interval attribute is the time interval for continuously receiving keepalive and update messages. If a keepalive or update message is received, the holding timer is reset. If a router has not received any messages from the opposite router for a specific period of holding time, this BGP connection is considered broken and is cut off. The router can negotiate with the interconnected router to set a shorter holding time.

Perform the following configurations in BGP view.

Table 525 Configure the Keepalive Timer and Holdtime Tmer for BGP

Operation	Command
Configure the keepalive timer and	timers keepalive-interval
holdtime timer for BGP	holdtime-interval
Restore BGP network timers to their	undo timers
default value

By default, the value for the keepalive-intervalattribute is 60 seconds and may have a value ranging from 1 to 4294967295 seconds. The default value for the