Description of Passive-interface commands in dynamic Router Protocol

Many people may not have a special understanding of configuring the dynamic Router Protocol. Here we mainly introduce the Passive-interface command in the dynamic Router Protocol, and managing network bandwidth is becoming more and more important. In a network without other routers, it is meaningless to route the Broadcast Communication outbound from the network interface. This is very inefficient for your network bandwidth and vro resources. Let's take a look at how to use the passive-interface command to better control the bandwidth.

To correctly configure the dynamic Router Protocol, the passive-interface command is not unknown. However, if you are not using dynamic router protocols such as OSPF, OSPF, or RIP, you will not be able to use this command. The passive-interface command only works in the Router Configuration Mode ). When you see the following command line prompt, you will know that you have entered this mode: Routerconfig-router ), you can use the passive-interface command to notify the dynamic Router Protocol not to send network broadcasts through this interface. This command can take effect for all IP dynamic router protocols, except for BGP.

However, this command works on OSPF, which IS a little different from IS-IS. OSPF is used to passively specify the network interface as the stub detail area), and no route updates are sent or received. When using RIP, IGRP, and VPN, it does not send any routes, but it can receive them. Similarly, it sends broadcasts to all non-passive interfaces on the network. There are two ways to use the passive-interface command. Specify an interface as the passive mode, which means it will not send route updates. First, set all interfaces to passive mode. Then, use the no passive-interface command on the interfaces you want to send route updates. Let's look at an example for each of the two methods. Note: in both cases, it is assumed that you have added network commands for networks where the dynamic Router Protocol is a passive interface ). To change an interface to passive mode, you only need to specify the interface. Here is an example: Routerconfig) # router rip Routerconfig-router) # passive-interface Ethernet 0/0.

To set all interfaces as passive and open an interface separately, you only need to use the passive-interface default and no passive-interface commands in IOS 12.0 ). The following is an example: Routerconfig) # router rip Routerconfig-router) # passive-interface default Routerconfig-router) # no passive-interface Serial 0/0.

Let's look at a simple network dedicated to demonstrating the deep application of this command. Suppose you have two routers connected through a T1 loop, and the routers run RIP. Each router connects to a LAN, and the computer connects to the LAN through the ethernet card. You need to know the network of each vro, right? This is why dynamic routing is used. However, on the LAN, no other routers can exchange route updates between the two routers. In this case, why do you want to broadcast a route update on the LAN interface every 30 seconds? The answer is that you don't want. This is a waste of LAN bandwidth and computer CPU time. If it is just a small update, it does not cause any problems, but if you can avoid it, why do you send such unnecessary communication?

So how can we eliminate such unnecessary communication? On each vro, enter the RIP Configuration mode in the RIP Configuration mode), and use the passive-interface command to stop sending route updates on the LAN port. The following is an example: Routerconfig) # router RIP Routerconfig-router) # passive-interface Ethernet 0/0. This, of course, assumes that you have used network commands in advance to configure the network to be broadcast. The following is an example: Routerconfig-router) # network 1.0.0 ...... 0 the Serial network), Routerconfig-router) # network 2.0.0.0 the Ethernet network ).

Remember, this means that the system broadcasts the two networks you set by connecting to the serial interface of another vro. In addition, this does not prevent your router from using RIP from using the local network interface) to receive route updates. If another vro is also on the LAN and sends updates to your vro, it can still receive these updates.