Passive-Interface Command on CISCO Router/Switch

Command

Passive-Interface

Use

This command disables RIP for a specific interface on the router.

Syntax

Router(config-router)#passive-interface <interface>

Example

First, here are the route tables for all routers with no passive-interface default.

R2#conf t
Enter configuration commands, one per line. End with CNTL/Z.
R2(config)#router rip
R2(config-router)#no passive-interface default

R1 route table.

R1(config-router)#do show ip route rip
2.0.0.0/32 is subnetted, 1 subnets
R 2.2.2.2 [120/1] via 10.1.1.2, 00:00:15, FastEthernet0/0
R 3.0.0.0/8 [120/2] via 10.1.1.2, 00:00:15, FastEthernet0/0
10.0.0.0/24 is subnetted, 2 subnets
R 10.2.2.0 [120/1] via 10.1.1.2, 00:00:15, FastEthernet0/0

R2 route table.

R2(config-router)#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, 00:00:12, FastEthernet0/0
R 1.3.3.3 [120/1] via 10.1.1.1, 00:00:12, FastEthernet0/0
R 1.2.2.2 [120/1] via 10.1.1.1, 00:00:12, FastEthernet0/0
R 3.0.0.0/8 [120/1] via 10.2.2.3, 00:00:21, FastEthernet1/0

R3 route table.

R3(config-router)#do show ip route rip
1.0.0.0/32 is subnetted, 3 subnets
R 1.1.1.1 [120/2] via 10.2.2.2, 00:00:00, FastEthernet0/0
R 1.3.3.3 [120/2] via 10.2.2.2, 00:00:00, FastEthernet0/0
R 1.2.2.2 [120/2] via 10.2.2.2, 00:00:00, FastEthernet0/0
2.0.0.0/32 is subnetted, 1 subnets
R 2.2.2.2 [120/1] via 10.2.2.2, 00:00:00, FastEthernet0/0
10.0.0.0/24 is subnetted, 2 subnets
R 10.1.1.0 [120/1] via 10.2.2.2, 00:00:00, FastEthernet0/0

Next, we disable passive-interface for interface fa1/0 on R2.

R2(config-router)#passive-interface fa1/0

R1 route table. R2 still passes route information to R1 via fa0/0

R1(config-router)#do show ip route rip
2.0.0.0/32 is subnetted, 1 subnets
R 2.2.2.2 [120/1] via 10.1.1.2, 00:00:11, FastEthernet0/0
R 3.0.0.0/8 [120/2] via 10.1.1.2, 00:00:11, FastEthernet0/0
10.0.0.0/24 is subnetted, 2 subnets
R 10.2.2.0 [120/1] via 10.1.1.2, 00:00:11, FastEthernet0/0

R2 route table. This is unaffected because R2 is still receiving updates from R1 and R3.

R2(config-router)#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, 00:00:10, FastEthernet0/0
R 1.3.3.3 [120/1] via 10.1.1.1, 00:00:10, FastEthernet0/0
R 1.2.2.2 [120/1] via 10.1.1.1, 00:00:10, FastEthernet0/0
R 3.0.0.0/8 [120/1] via 10.2.2.3, 00:00:02, FastEthernet1/0

R3 route table. It is blank because R3 no longer receives updates through R2 via fa1/0

R3(config-router)#do show ip route ripR3(config-router)#

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