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blackhole route

aksher
Level 1
Level 1

what's a black hole route.

7 Replies 7

pkhatri
Level 11
Level 11

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

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

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

PK

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

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

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

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

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