Configuring RIPng Timers
Context
RIPng uses 4 timers: Update, Age, Suppress, and Garbage-collect. Changing the timer values affects the convergence speed of RIPng routes.
Procedure
- Run system-view
The system view is displayed.
- Run ripng [ process-id ] [ vpn-instance vpn-instance-name ]
The RIPng process is enabled and the RIPng view is displayed.
- Run timers ripng update age suppress garbage-collect
RIPng timers are configured.
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RIPng timers take effect immediately after being changed.
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Route flapping occurs if the values of the four timers are set improperly. The relationship between the values is as follows: update must be smaller than age and suppress must be smaller than garbage-collect. For example, if the update time is longer than the aging time, and a RIPng route changes within the update time, the switch cannot inform its neighbors of the change on time.
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You must configure RIPng timers based on the network performance and uniformly on all the routers running RIPng. This avoids unnecessary network traffic or route flapping.
By default, the Update timer is 30s; the Age timer is 180s; the Suppress timer is 0s; the Garbage-collect timer is four times the Update timer, namely, 120s.
In practice, the Garbage-collect timer is not fixed. If the Update timer is set to 30s, the Garbage-collect timer may range from 90s to 120s.
Before permanently deleting an unreachable route from the routing table, RIPng advertises this route (with the metric being set to 16) by periodically sending Update packets four times. Subsequently, all the neighbors know that this route is unreachable. Because a route may not always become unreachable at the beginning of an Update period, the Garbage-collect timer is actually three or four times the Update timer.
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- Run commit
The configuration is committed.
