|My site seems unusually slow or difficult to reach.|
|What is a traceroute?|
|How do I run traceroute?|
|How do I interpret the traceroute results?|
My site seems unusually slow or difficult to reach.
We will gladly assist you in identifying possible network problems reaching our service. Although we cannot control network performance outside of our own network, we may be able to address the matter through our backbone providers or advise you on who to contact.
Before submitting any report, please check our System Notices to see if there is an outstanding network or server issue that might be the cause of your problem. If a notice has been posted, we are actively working on the issue.
If no notice is present, please run a traceroute and send the results to us, as well as your computer’s IP address so we can perform a trace out to you. If the problems seem to recur at a particular time of day, please login to your account and run a traceroute back to your own IP address, and provide a copy of that output as well.
To determine your computer’s IP address, visit http://ipadd.info, and it will display your computer’s IP address for you.
What is a traceroute?
A traceroute is an internet application that details the path from a client machine (your computer) to a specific host computer. It displays the time it takes to travel to the destination computer as well as a description of the “hops,” or the jumps to a network router or gateway, along the path. Traceroutes are useful tools to help diagnosis network problems.
How do I run traceroute?
The Windows operating system also includes a traceroute application called tracert (used from the MS-DOS command line). For Mac OS X users, you can use the traceroute application in the Network Utility (which can be found in the Utilities directory). You can run a traceroute on a UNIX computer with the “traceroute” command. There are graphical traceroute tools available as well.
To run a traceroute using Windows XP, please do the following:
- Click Start
- Click Accessories
- Click C:// Command Prompt (MS-DOS Prompt)
- Type tracert and the IP address or website address (when the C:// prompt appears)
Please be sure to leave a space between the tracert command and the IP address or Web site address.
To run a traceroute using Mac OS X, please do the following:
- Click Macintosh HD
- Click Applications
- Click Utilities
- Click Network Utility
- Select the Traceroute Tab
- Enter the IP address or website address
To run a traceroute using UNIX, please do the following:
- Open a terminal window
- Type traceroute and the IP address or website address
Please make sure there is a space between the command traceroute and the IP address or website address.
Here is the typical output of a traceroute, in this case from our network
to the BBC Web site:
traceroute to www.bbc.net.uk (18.104.22.168), 64 hops max, 44 byte packets
1 baal.pair.net (192.168.1.8) 0.453 ms 0.287 ms 0.346 ms
2 sl-gw9-rly-6-0.sprintlink.net (22.214.171.124) 6.250 ms 5.888 ms 5.889 ms
3 sl-bb23-rly-3-0.sprintlink.net (126.96.36.199) 181.786 ms 207.330 ms 227.133 ms
4 sl-bb21-pen-12-0.sprintlink.net (188.8.131.52) 8.420 ms 8.548 ms 8.356 ms
5 sl-bb22-pen-15-0.sprintlink.net (184.108.40.206) 8.537 ms 8.384 ms 8.558 ms
6 sl-bb23-pen-15-0.sprintlink.net (220.127.116.11) 8.597 ms 8.593 ms 8.448 ms
7 sl-bb26-nyc-4-0.sprintlink.net (18.104.22.168) 12.680 ms 12.481 ms 12.589 ms
8 sl-gw9-nyc-9-0.sprintlink.net (22.214.171.124) 12.329 ms 12.294 ms 12.186 ms
9 sl-bbcte-1-0.sprintlink.net (126.96.36.199) 12.608 ms 12.545 ms 12.655 ms
10 www10.thny.bbc.co.uk (188.8.131.52) 12.019 ms 11.630 ms 12.051 ms
Each line of output is one “hop” along the path your connection
is most likely taking to the destination. The three numbers indicate how
many milliseconds the router or switch at that hop took to reply to the
three probes sent to that hop. An asterisk indicates no response was
received; this may or may not indicate a problem.
Many trace attempts will not reach the destination, due to the presence of a firewall or filter. Such traces will end with a series of asterisks or a filtered reply such as “!X”.
How do I interpret the traceroute results?
The results must be interpreted very carefully; it is easy to jump to unwarranted conclusions. Having a trace in both directions is essential to avoiding several common misinterpretations.
If a single hop has unusually high response times, this is usually the sign of an overloaded router. However, an overloaded router does not necessarily mean slow transfer; modern routers rarely pass packets through their central processor.
If a single hop consists of nothing but asterisks, but the trace continues
afterwards, this hop represents a router or switch that successfully routes
traffic but does not respond to traceroutes, or responds with a non-public
IP address which your ISP filters. In particular, you may see this when
tracing inbound to our network.
If dropped responses start to appear at a particular hop, and continue through the remaining hops, this may indicate that a congested link is present at the first such hop. However, it may also indicate that the return path changes at that point, and that the problem actually lies in that return path.