Management of network bandwidth is becoming increasingly important. In the absence of other routers on the network, the network interface routing out of the radio communication is meaningless. This use of resources on your router, its efficiency is very low. Let's take a look at how to use the passive-interface command, to make better bandwidth control.
To correctly configure routing protocol, passive-interface command is one I do not know. However, if you are not using dynamic routing protocols (such as OSPF, EIGRP, or RIP), then you fall do not need this command.
passive-interface command only works in Router Configuration Mode (Router Configuration Mode). When you see the command prompt looks like this when you know that they have access to the mode of:
Router (config-router)
You can use the passive-interface command to tell the dynamic routing protocol not to send a network broadcast by the interface. This command allows all of the IP routing protocols except BGP only.
However, the command to work in OSPF, and IS-IS in a little differently. With OSPF, the network interface specified as passive stub (distal region) appear not to send and receive any routing updates. Using RIP, IGRP, and EIGRP, it does not send any routing, but it can receive them. Similarly, it will be a network interface to send all non-passive radio.
Using the passive-interface command in two ways.
Specify an interface as passive mode, which means it will not send routing updates.
First set to passive mode for all interfaces. Then you want to send routing updates interface, use the no passive-interface command.
Let us come to the right are two ways to look at an example. Note: Each example assumes that you have already added to the routing protocol is a passive interface to the network (using the network command).
To an interface into passive mode, just specify the interface. Here is an example:
Router (config)
# Router rip Router (config-router)
# Passive-interface Ethernet 0 / 0
Set all interfaces to passive, and then open a separate interface, just use the passive-interface default and no passive-interface command (described in the IOS 12.0). The following is a sample:
Router (config)
# Router rip Router (config-router)
# Passive-interface default Router (config-router)
# No passive-interface Serial 0 / 0
Let's look at a simple network, dedicated to the underlying application model of the order. Suppose you have two routers connected via a T1 circuit, and the routers are running RIP. Each router has a LAN, the computer connected to the LAN through the Ethernet card.
You need each router to know each other a network router, right? This is why you want to use dynamic routing protocols that purpose. However, the LAN, there are no other routers, these routers can exchange routing updates.
In this case, why would you want every 30 seconds on the LAN interface to broadcast routing updates, forever? The answer is you do not want. This is a computer on the LAN bandwidth and CPU time to waste. If it is just a small update, it does not cause any problems, but if you can avoid, why send this unnecessary traffic?
So how can you eliminate this unnecessary traffic? In each router, enter the RIP configuration mode (RIP Configuration mode), and use the passive-interface command to stop sending routing updates on the LAN port. The following is an example:
Router (config)
# Router RIP Router (config-router)
# Passive-interface Ethernet 0 / 0
This, of course, assuming you have pre-configured using the network command intends to broadcast the network. Here's an example:
Router (config-router)
# Network 1.0.0 ... ... 0 (the Serial network)
Router (config-router)
# Network 2.0.0.0 (the Ethernet network)
Remember, this means that the system is connected to another router via the serial interface, you set the two networks will be broadcast. In addition, it does not stop your router from the local area network interface (using RIP) routing updates received. If you also happened to another LAN router, your router to send an update, it can still receive these updates.