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Beginner

blackhole route

what's a black hole route.

7 REPLIES
Advisor

Re: blackhole route

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

Beginner

Re: blackhole route

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

Advisor

Re: blackhole route

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

PK

Highlighted
Beginner

Re: blackhole route

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

Beginner

Re: blackhole route

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

Advisor

Re: blackhole route

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

Beginner

Re: blackhole route

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

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