When i say NULL ROUTE or BLACK HOLE ROUTING the first thing comes in your mind is what the hell is this?
What kind of interface is this NULL 0?
What is black hole in Router?
What is need of Null route in Networking?
Who used it and why?
In this tutorial you will get all the answer and will also learn what is Null Routing ,how to configure Null routing and why we use Null routing.
In computer network NULL ROUTE(BlackHole Route) is a network route which goes nowhere.Or you can say null route or a blackhole route is a route which divert the network in a black hole from where it never come back again.it is a type of Trash or Recycle Bin for route packets.People or company used this to drop some specific network or stop ddos attack.All traffic sent to null interface is discarded.IT person or Network Engineers used it discard traffic simply by routing it to null interface.
Note:You can filter or DROP Packet even by using ACL but Null Route is best because Access List Required More CPU overhead.
Here I am going to BLOCK PACKETS GENERATED FROM Router0 188.8.131.52 network for 184.108.40.206 network
ROUTING CONFIGURATION ON ROUTER0:
Remember we will configure NULL ROUTE on This Router.
Router(config)#ip route 220.127.116.11 255.0.0.0 18.104.22.168 Router(config)#ip route 22.214.171.124 255.0.0.0 126.96.36.199 Router(config)#ip route 188.8.131.52 255.0.0.0 null0
ROUTING CONFIGURATION ON ROUTER1:
ROUTING CONFIGURATION ON ROUTER2:
You can see when Person seating on PC in network 184.108.40.206 trying to communicate with person in network 220.127.116.11 packets drop.
PC>ping 18.104.22.168 Pinging 22.214.171.124 with 32 bytes of data: Reply from 126.96.36.199: Destination host unreachable. Reply from 188.8.131.52: Destination host unreachable. Reply from 184.108.40.206: Destination host unreachable. Reply from 220.127.116.11: Destination host unreachable. Ping statistics for 18.104.22.168: Packets: Sent = 4, Received = 0, Lost = 4 (100% loss), PC>