A reasonable latency to expect between Chicago and London would be 92ms RTT. Brian Knoll -----Original Message----- From: owner-nanog@merit.edu [mailto:owner-nanog@merit.edu] On Behalf Of Neal R Sent: Thursday, June 28, 2007 6:21 PM To: nanog@merit.edu Subject: trans-Atlantic latency? I have a customer with IP transport from Sprint and McLeod and fiber connectivity to Sprint in the Chicago area. The person making the decisions is not a routing guy but is very sharp overall. He is currently examining the latency on trans-Atlantic links and has fixed on the idea that he needs 40ms or less to London through whatever carrier he picks. He has spoken to someone at Cogent about a point to point link. What is a reasonable latency to see on a link of that distance? I get the impression he is shopping for something that involves dilithium crystal powered negative latency inducers, wormhole technology, or an ethernet to tachyon bridge, but its been a long time (9/14/2001, to be exact) since I've had a trans-Atlantic circuit under my care and things were different back then. Anyone care to enlighten me on what these guys can reasonably expect on such a link? My best guess is he'd like service from Colt based on the type of customer he is trying to reach, but its a big muddle and I don't get to talk to all of the players ...