In a computer network that uses the Routing Information Protocol (RIP) or other distance vector routing protocols, a poison reverse is a way in which a gateway node tells its neighbor gateways that one of the gateways is no longer connected. To do this, the notifying gateway sets the number of hops to the unconnected gateway to a number that indicates "infinite" (meaning "You can't get there"). Since RIP allows up to 15 hops to another gateway, setting the hop count to 16 would mean "infinite."
This was last updated in January 2000