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I administer a custom-built asp.net web app for a client. This client often complains of the website "hanging" and not completing page loads. I have never once experienced any such behavior with this site. Based on his descriptions, I believe the problem may be a bad route between his ISP (Comcast) and the web host. Any suggestions on how best to diagnose packetloss between his desktop and the server?

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5 Answers 5

up vote 1 down vote accepted

I've used Smokeping in the past to monitor latency and loss between hosts. It has a daemon that runs and periodically pings your specified hosts. It then makes nice graphs that show latency and packet loss trends over time. That should get you a better idea of whether or not the issues are happening at a specific time or under certain circumstances.

Additionally, I'd recommend mtr over the "vanilla" ping and traceroute tools. It combines the two into a nice interface and makes it quite easy to see if (and where) packet loss is happening. One thing to keep in mind, though, is that intermediary routers oftentimes place a low priority on responding to ICMP packets, which both ping and traceroute rely on. If you see packet loss happening on a single intermediary router, but not on subsequent routers, then this is likely what's happening. On the other hand, if packets are getting dropped by one router, and you see the same loss on all subsequent routers, then there's likely a problem.

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Good information, points me to the tools that will work for the situation, thanks. –  user11881 Sep 25 '09 at 22:09
  • ping
  • tracert

Look at latency, packets lost, number of hops and similar

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says user friendly, not sure these fit the bill. –  Roy Rico Sep 25 '09 at 18:04
1  
can you think something more friendly than ping hostname ? :) –  AlberT Sep 25 '09 at 18:57

I like ping plotter as it is super simple to use and read. http://www.pingplotter.com/freeware.html

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Ping/tracert will only show latency, packet loss etc etc when you run them.

Might be worth trying a package capture and getting the client to let you know when the issue happens - particularly useful if you've got the disk space to let it run. Wireshark (http://www.wireshark.org) is good and it can show you whether there are retransmissions and other nasty things. Ethereal can show you lots of other stuff such as response time which may assist if it doesn't turn out to be a network issue.

If you leave it running though keep an eye on your disk space though.

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Just to clarify, for anyone who might read Paul's post: Wireshark used to be called Ethereal. :) –  rob Sep 25 '09 at 19:29

An old GPL Windows build of MTR ( http://winmtr.sourceforge.net ) came in handy in the NOC quite a few times. We asked our customer to have their customer unzip it, run it for a few hundred cycles and then paste us the output in an email/ticket update which we could then forward onto Network Engineering. For best results get one in each direction if possible: web client to web server, and web server back to IP (or next hop) of web client.

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