A system, method, and node for protecting a telecommunication system against a mobile and multi-homed attacker, MMA (10). The telecommunication system includes one or more correspondent nodes, CN, (102, 104) for transferring data packets. A mobile and multi-homed network node, MMN, (108) associated with the MMA communicates and receives data packets with the CN. An access router, AR, (106) transferring data between the MMN and the CN performs a reachability test with the MMN to determine if the MMN is still reachable. The AR sends a message to the CN to flush cached information associated with the MMN if the MMN is not reachable by the AR. The CN, upon receiving the message to flush cached information, flushes binding cache entries associated with the MMN from the CN.