blackhole route

[aksher]

what's a black hole route.

[pkhatri]

The intention of a black-hole route is to draw traffic to a destination, only to discard it. You achieve it by creating a route to null0. For example, if you configured the following 'ip route 10.0.0.0 255.0.0.0 null0', and redistributed it into a routing protocol, all traffic for 10.0.0.0/255.0.0.0 woudl head to the router where they would get dropped.

Paresh

[aksher]

what if we use no ip route...............

[pkhatri]

Not sure what you mean by that... you gotta have a route in order to point it to Null0.

PK

[aksher]

i mean instead of using a black hole route can we use a no ip route statement to remove the route for the destination.

[aksher]

i mean instead of using a black hole route can we use a no ip route statement to remove the route for the destination.

[pkhatri]

If you do that, then the only thing that will do is to discard any packets for any destinations not known by the router (assuming it does not have a default route). However, the rest of the network does not learn of the route that is being black-holed.. you need to create a route to Nullo and tell the rest of the network about it.

Paresh

[Tony.henry]

Routing to null has the added value that no ICMP destination unreachable will be sent back to the sending station.