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Passive Interfaces

The function of a passive interface is to stop the router from sending hello packets.

Configuration example with OSPF

Section titled “Configuration example with OSPF”
Router(config)# router ospf 1
Router(config-router)# passive-interface GigabitEthernet0/0

Default Passive

Section titled “Default Passive”

In big networks the best strategy is to put all interfaces in passive mode by default, activating only the ones that go to other routers.

Router(config-router)# passive-interface default
Router(config-router)# no passive-interface GigabitEthernet0/1

Why use passive-interface on a Loopback?

Section titled “Why use passive-interface on a Loopback?”

Even though the Loopback is virtual, the router’s CPU still works to generate those packets every 10 seconds which are automatically discarded by the router. It’s a waste of CPU cycles.