>does anyone have an idea what might be wrong on the isp's routers to >have these problems? (they're using cisco and juniper iron...) or is it >a kernel bug? LiNUX kernel is right. There is a bug in a lot of TCP/IP implementations out there. linux-net threads: http://marc.theaimsgroup.com/?t=108913991800005&r=4&w=2 'TCP window scaling and broken routers': http://lwn.net/Articles/92727/