Timers Command on CISCO Router/Switch

Command

Timers

Use

Changes the RIP timers associated with RIP on the router.

Syntax

Router(config-router)#timers basic <update interval> <invalid> <holddown> <flush> <sleep time>

Options

<update interval> Time between route updates
<invalid> Time interval that determines that a route is down
<holddown> Route is no longer used but is still held in routing table
<flush> How long until route is removed from routing table
<sleep time> The time between rip packets

Example

For this example, rip timers are set on R1, R2, and R3 using the below commands.

R1#conf t
Enter configuration commands, one per line. End with CNTL/Z.
R1(config)#router rip
R1(config-router)#timers basic 15 45 60 85
R2#conf t
Enter configuration commands, one per line. End with CNTL/Z.
R2(config)#router rip
R2(config-router)#timers basic 15 45 60 85
R3#conf t
Enter configuration commands, one per line. End with CNTL/Z.
R3(config)#router rip
R3(config-router)#timers basic 15 45 60 85

To simulate what happens when a rip route is lost, int fa0/0 on R1 is shut down.

R1(config-router)#int fa0/0
R1(config-if)#shut

Now, after 41 seconds of R1 being down, the rip route is still active on R2.

R2(config-if)#do show ip route rip
1.0.0.0/32 is subnetted, 3 subnets
R 1.1.1.1 [120/1] via 10.1.1.1, 00:00:41, FastEthernet0/0
R 1.3.3.3 [120/1] via 10.1.1.1, 00:00:41, FastEthernet0/0
R 1.2.2.2 [120/1] via 10.1.1.1, 00:00:41, FastEthernet0/0
3.0.0.0/32 is subnetted, 1 subnets
R 3.3.3.3 [120/1] via 10.2.2.3, 00:00:02, FastEthernet1/0

45 seconds after shutting down R1’s int fa0/0, the status of the routes is set to “possibly down”.

R2(config)#do show ip route rip
1.0.0.0/32 is subnetted, 3 subnets
R 1.1.1.1/32 is possibly down,
routing via 10.1.1.1, FastEthernet0/0
R 1.3.3.3/32 is possibly down,
routing via 10.1.1.1, FastEthernet0/0
R 1.2.2.2/32 is possibly down,
routing via 10.1.1.1, FastEthernet0/0
3.0.0.0/32 is subnetted, 1 subnets
R 3.3.3.3 [120/1] via 10.2.2.3, 00:00:06, FastEthernet1/0

90 seconds after, the route is lost.

R2(config)#do show ip route rip
3.0.0.0/32 is subnetted, 1 subnets
R 3.3.3.3 [120/1] via 10.2.2.3, 00:00:05, FastEthernet1/0

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