What is Passive Interface?

--> Passive Interface is a feature used by routing protocol to stop sending updates on the particular interface.

--> Basically this command is applied on the router interface which is connected to LAN or Loopback.

--> Routing updates are only understood by the routers.

--> In the below scenario, there is no use of sending of updates on the fa0/0 interface.

--> Passive Interface feature works differently for each routing protocol.

RIP

--> Prevents Sending multicast updates on a passive interface.

--> Sends unicast updates on the passive interface if the neighbor command is configured.

--> Receives unicast and multicast on the interface.

Configuration:

Router rip

Passive-interface fa0/0

EIGRP

--> Prevents Sending of hello messages on a passive interface.

--> The router does not form any relationship on the passive interface.

--> Prevents sending and receiving of routing updates on the Passive interface.

Configuration:

Router eigrp 100

Passive-interface fa0/0

OSPF

--> Prevents Sending of hello messages on a passive interface.

--> The router does not form any relationship on the passive interface.

--> Prevents sending and receiving of routing updates on the Passive interface.

Configuration

Router ospf 1

Passive-interface fa0/0

Reference: Cisco.com

Md.Kareemoddin

CCIE #54759