Network Performance Troubleshooting

MTR

MTR is a network tool for diagnosing and isolating networking errors. It combines ping and traceroute to show information about each hop in the network.

Windows

  • WinMTR can be downloaded from the WinMTR website.
  • Turn off Resolve names in the Options menu.
  • Enter server.whatbox.ca in the Host field.
  • Press Start and wait until at least 100 packets are sent.

Linux and Mac OSX

  • You may need to install MTR using your operating system's package manager.
    • Ubuntu/Debian: apt-get install mtr-tiny
    • CentOS/Fedora: yum install mtr
    • Gentoo: emerge mtr
    • OSX w/ Homebrew: brew install mtr
    • OSX w/ MacPorts: port install mtr
  • Run MTR for 100 packets: mtr -zbrewc 100 server.whatbox.ca

MTR Results

Timeouts

Some routers along the path may not respond to MTR's packets. When this happens, the hop will show ???. This usually is not a cause for concern as long as the destination host (i.e. the server) still responds.

Alternatively, if only the destination shows ???, it is still possible the host is up, but not responding to MTR's packets.

Packet loss

If a single hop shows packet loss but it does not persist to subsequent hops, it is possible the router has ICMP rate limiting in place. This is a common practice to prioritize more important traffic and is no cause for concern.

If the packet loss does persist to subsequent hops, this can be indicative of congestion or other network problems.

Traceroute

traceroute is a computer network diagnostic tool for displaying the route (path) and measuring transit delays of packets across an Internet Protocol (IP) network. It's a great way to inspect the routing to your box.

Windows

  • Open the command prompt:
    • Windows 7 or Vista: From the Start menu, in the search field, type "cmd" and then press Enter
    • Previous versions: From the Start menu, select Run... . In the "Open:" box, type "cmd" and then press Enter
  • At the command prompt, enter tracert server.whatbox.ca

Linux and Mac OS X

Open the Terminal app and type traceroute server.whatbox.ca

Understanding the results

You will get something like this:

Tracing route to www.indiana.edu [129.79.78.8]

over a maximum of 30 hops:

1   <10 ms   <10 ms   <10 ms  168.91.41.1 
2    10 ms    20 ms    20 ms  indy-bloomington-s4-6.ivy.tec.in.us [168.91.9.129] 
3    10 ms    10 ms    20 ms  akicita-lena.ivy.tec.in.us [168.91.1.4] 
4    20 ms    30 ms    30 ms  indnet.ivy.tec.in.us [168.91.1.130] 
5    71 ms    40 ms    50 ms  ind-s1-0-7-T1.ind.net [157.91.8.62] 
6    80 ms    40 ms    40 ms  serverfarm-atm0.ind.net [199.8.76.231] 
7    60 ms    90 ms    80 ms  iupui-atm6-0-100.ind.net [157.91.9.78] 
8    50 ms    40 ms    90 ms  indy-dmz.atm.iupui.edu [134.68.15.103] 
9     *        *        *     Request timed out.
10    40 ms    70 ms    90 ms  wcc6-gw.ucs.indiana.edu [129.79.8.6] 
11     *       40 ms    50 ms  viator.ucs.indiana.edu [129.79.78.8] 

Trace complete.

The first column, the hop count, represents the number of stops your information has made along the route to attempt to contact the other computer. The next three columns are the round-trip times in milliseconds for three different attempts to reach the destination. The last column is the name of the host that responded to the request.

The above example shows that a computer user on ivy.tec.in.us ran a traceroute to www.indiana.edu. On the fifth hop, the request left the Ivy Tech network and went to the ind.net network. On the eighth hop, the request went to the iupui.edu network. Finally, on the tenth hop, the request found its way to the indiana.edu network. Since there is a "Request timed out" message on the ninth hop, you might guess that there could be some problem between the iupui.edu network and the indiana.edu network. If you are seeing other problems, such as the web page at http://www.indiana.edu/ loading slowly, this could indicate the location of the problem.