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Re: ping packet loss when size gt 1500

Chris Davies on 19/10/10 16:24, wrote:
Adam Hardy <adam.ant@cyberspaceroad.com> wrote:
I have a question about traceroute that might be relevant. I haven't
figured out the traceroute options because on lenny, my traceroute
doesn't complete. The last hop to mktgw1.ibllc.com doesn't show - it
just counts stars up to 30. But on windows it does complete at 23 -
where mktgw1.ibllc.com is the last hop / target. Does this betray

Traceroute on Linux and Windows platforms typically use different packet
types. IIRC, tracert uses ICMP 8 (ping) whereas traceroute uses UDP. My
flavour of traceroute accepts the -I flag to force ICMP 8.

My version of traceroute also has the --mtu option, which tries to
determine the MTU for the route being traced. It looks perhaps like the
firewall for interactivebrokers (IP *may* be blocking too
many ICMP control message types - including the MTU/Fragment messages.

The problem is, it doesn't look good from their point of view. I have a problem but their other 150,000 customers don't. I have a manually configured gateway, iptables firewall and all - their other 150,000 customers use mostly windows, although there are an unknown number of linux users out there - it's a java app.

I have so far only a couple of things to go on - communication with their server shows inexplicable MTU behaviour, and there is a weak link on the British Telecom part of the traceroute.

All tests on my LAN show that I am running normally though. I've tested my mtu size, my firewall, my DHCP, my DNS (now using OpenDNS).

Any ideas where to go from here?


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