BROCADE IP PRIMER

The “Null” RouteTo see RIP's routing table and any additional global configuration settings:BR-Switch#show ip ripFinally, with that in mind, remember this as well. RIP will only advertise directlyconnected routes and routes from the RIP routing table. By default, RIP will notadvertise static routes, or routes learned from any other routing protocol. If youwant RIP to advertise routes that it has learned from other protocols (includingstatic routes), you need to set up route redistribution. This is very easy to setup.BR-Switch#conf tBR-Switch(config)#router ripBR-Switch(config-rip-router)#redistributionRIP will now advertise static routes and routes that your router has learnedfrom other protocols.The “Null” RouteThere's a funny little trick that's included in Brocade switches. You have theability to forward packets to, well, nowhere. Why in the world would you want todo this? Well, let's say, you're administering a Corporate LAN. You've discoveredthat quite a few of the company's employees have been wasting theirtime going to a particular web site. The boss wants you to put a stop to this.Now, you could use a firewall, but some firewalls only protect traffic coming infrom the outside. In this case, you want to stop traffic from the inside goingout. Implementing a proxy server is also a popular solution, but you have neitherthe time nor the budget. Instead, you can add a static route to your router.You tell it to forward the network range for that web site to “null0.” Null0 is aspecial interface that tells the router to simply drop the packet. It is configuredlike this:BR-Switch#conf tBR-Switch(config)#ip route 169.254.213.0/24 null0Notice that the only gateway I specified is “null0.” Now, imagine if you wereusing route redistribution, and you wanted to quickly make sure that no one onany of your routers could go to this network. One static route to “null0” on oneof your routers is all it takes. Thanks to dynamic routing protocols and routeredistribution, in a short time, this null route will be in all of your routers' routingtables.Summary• You can disable Layer 2 functions on a switch that is running router codeby using the route-only command• route-only can be used on individual interfaces or globally• A router stores all of the routes it knows about in a routing table• You can use the show ip route command to see the contents of the routingtableBrocade IP Primer 235