What Is The Purpose Of The Passive-Interface Command?

What is the purpose of the passive-interface command?

• The updates which are missed out of an interface the passive-interface permits to forward them.
• Permit them to the router to send the updates on an interface but not be able to receive them with an interface.
• The interface has the permit to remain up without any receiving keepalives.
• The interface can share the IP address.
• Permit them to the router to send the updates on an interface but not be able to send them with an interface. 

Answer: The purpose of the passive-interface command is to Permit the router to send the updates on an interface but not be able to send them with an interface.

What is a passive-interface command?

The passive-interface command is used to tell the interface to listen to the routes of RIP or IGRP but not broadcast them. to disable the ability to broadcast on the interface the router assigned to” just listen but don’t talk”. The command help to lessen the load on the CPU by minimizing the interface numbers which are protocol used for communication. The command blocks the processing of routes for the OSPF or EIGRP. Carefully use the command when you don’t want the routing protocols to talk to a specific interface.

Reasons to enable the passive-interface command

When the interface is enabling near the EIGRP network, the network might try to make the adjacency with the neighbor’s router and make it send and receive the update of its network. The command work to prevent the adjacency of the neighboring network.The reason for the passive command work is described below:

• It can reduce the unwanted traffic update, as the interface is a LAN interface without any connection to the network.
• The security increased, it can prevent the unknown devices from receiving any kind of EIGRP updates.

Configuration and verification of the command

The interface router configuration can block the transmission of the EIGRP hello packets with help of the commands:

• Router (config) # router eigrp as-number
• Router (config-router) # passive-interface interface-type interface-number

According to the reference topology the router 0 is no need to move the RIP updates to the interface LAN, rather it the router 0 is sending the updates to the computers connected LAN .it can be verified by allowing a debug on Router 0 with command <debug ip rip>  in the privileged exec mode. The verification can be also with the show ip protocol command 

The fast Ethernet 0/0 as passive interface and connect with LAN is configured. The process is described in the following:

•  Router0>enable
•    Router0#config terminal
•  Router0(config)#router rip
• Router0 (config-router) #passive-interface FastEthernet 0/1.

The interface is also configured for the dynamic protocol. The configuration is canceled with the <interface-id> command. The default command can also configure the passive-interface.