Quit wasting bandwidth by controlling Cisco routing protocol updates

router configuration

I found the method for helping controlling routing updates in cisco router.

Let's look at a simple networking scenario to further demonstrate the use of this command. Let's say that you have two routers connected via a T1 circuit, and the routers are running RIP. Each router has a LAN with PCs connected to an Ethernet interface.

You need each router to know about the other router's LAN network, right? That's the whole purpose of using the dynamic routing protocol .But there are no other routers on the LAN with which these routers can exchange routing updates.

If that's the case, why would you want to broadcast routing updates every 30 seconds on the LAN interface forever? The answer is that you don't. It's a waste of LAN bandwidth and a waste of your router's CPU time. While it isn't really causing a problem because it's a small update, there's no need to send unwanted traffic if you can avoid it.

So how can you eliminate this unnecessary traffic? On each router, go into RIP Configuration mode, and use the passive-interface command to stop sending routing updates on the LAN interface. Here's an example:

Router(config)# router RIP
Router(config-router)# passive-interface Ethernet 0/0