Kai what if UUnet is running some type of QOS mechanism in their core network that prevents massive amounts of icmp messages traveling through? Maybe they are rate-limiting everyone with CAR. Their infrastructure is interesting they use Cisco, Fore, and Juniper at least in production. And they claim they run an MPLS network; maybe this is where icmp traffic is killed.. Mufti Nayeem Ahmed Network Systems Engineer Market Data Networks Reuters America Inc. (212)-603-3595 ----------------------------------------------------------------- Visit our Internet site at http://www.reuters.com Any views expressed in this message are those of the individual sender, except where the sender specifically states them to be the views of Reuters Ltd.