computer science

MTR (software)

MTR (software) is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand MTR (software) rather than just read about it. In short: My traceroute, originally named Matt's traceroute (MTR), is a computer program that combines the functions of the traceroute and ping programs in one network diagnostic tool. MTR probes routers on the route path by limiting the number of hops individual packets may traverse, and listening to responses of their expiry.

Key takeaways

MTR (software) belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect MTR (software) to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of MTR (software) from memory before moving on to harder problems.

Reference excerpt

My traceroute, originally named Matt's traceroute (MTR), is a computer program that combines the functions of the traceroute and ping programs in one network diagnostic tool. MTR probes routers on the route path by limiting the number of hops individual packets may traverse, and listening to responses of their expiry. It will regularly repeat this process, usually once per second, and keep track of the response times of the hops along the path.

History The original Matt's traceroute program was written by Matt Kimball in 1997. Roger Wolff took over maintaining MTR (renamed My traceroute) in October 1998.

Fundamentals MTR is licensed under the terms of the GNU General Public License (GPL) and works under modern Unix-like operating systems. It normally works under the text console, but it also has an optional GTK+-based graphical user interface (GUI). MTR relies on Internet Control Message Protocol (ICMP) Time Exceeded (type 11, code 0) packets coming back from routers, or ICMP Echo Reply packets when the packets have hit their destination host. MTR also has a User Datagram Protocol (UDP) mode (invoked with "-u" on the command line or pressing the "u" key in the curses interface) that sends UDP packets, with the time to live (TTL) field in the IP header increasing by one for each probe sent, toward the destination host. When the UDP mode is used, MTR relies on ICMP port unreachable packets (type 3, code 3) when the destination is reached. MTR also supports IPv6 and works in a similar manner but instead relies on ICMPv6 messages. The tool is often used for network troubleshooting. By showing a list of routers traversed, and the average round-trip time as well as packet loss to each router, it allows users to identify links between two given routers responsible for certain fractions of the overall latency or packet loss through the network. This can help identify network overuse problems.

Examples This example shows MTR running on Linux tracing a route from the host machine (example.lan) to a web server at Yahoo! (p25.www.re2.yahoo.com) across the Level 3 Communications network.

My traceroute [v0.71] example.lan Sun Mar 25 00:07:50 2007

Packets Pings Hostname %Loss Rcv Snt Last Best Avg Worst 1. example.lan 0% 11 11 1 1 1 2 2. ae-31-51.ebr1.Chicago1.Level3.n 19% 9 11 3 1 7 14 3. ae-1.ebr2.Chicago1.Level3.net 0% 11 11 7 1 7 14 4. ae-2.ebr2.Washington1.Level3.ne 19% 9 11 19 18 23 31 5. ae-1.ebr1.Washington1.Level3.ne 28% 8 11 22 18 24 30 6. ge-3-0-0-53.gar1.Washington1.Le 0% 11 11 18 18 20 36 7. 63.210.29.230 0% 10 10 19 19 19 19 8. t-3-1.bas1.re2.yahoo.com 0% 10 10 19 18 32 106 9. p25.www.re2.yahoo.com 0% 10 10 19 18 19 19

An additional example below shows a recent version of MTR running on FreeBSD. MPLS labels are displayed by default when the "-e" switch is used on the command line (or the "e" key is pressed in the curses interface):

My traceroute [v0.82] dax.prolixium.com (0.0.0.0) Sun Jan 1 12:58:02 2012 Keys: Help Display mode Restart statistics Order of fields quit Packets Pings Host Loss% Snt Last Avg Best Wrst StDev 1. voxel.prolixium.net 0.0% 13 0.4 1.7 0.4 10.4 3.2 2. 0.ae2.tsr1.lga5.us.voxel.net 0.0% 12 10.8 2.9 0.2 10.8 4.3 3. 0.ae59.tsr1.lga3.us.voxel.net 0.0% 12 0.4 1.7 0.4 16.0 4.5 4. rtr.loss.net.internet2.edu 0.0% 12 4.8 7.4 0.3 41.8 15.4 5. 64.57.21.210 0.0% 12 5.4 15.7 5.3 126.7 35.0 6. nox1sumgw1-vl-530-nox-mit.nox.org 0.0% 12 109.5 60.6 23.0 219.5 66.0 [MPLS: Lbl 172832 Exp 0 S 1 TTL 1] 7. nox1sumgw1-peer--207-210-142-234.nox.org 0.0% 12 25.0 23.2 23.0 25.0 0.6 8. B24-RTR-2-BACKBONE-2.MIT.EDU 0.0% 12 23.2 23.4 23.2 24.9 0.5 9. MITNET.TRANTOR.CSAIL.MIT.EDU 0.0% 12 23.4 23.4 23.3 23.5 0.1 10. trantor.helicon.csail.mit.edu 0.0% 12 23.7 25.0 23.5 26.5 1.3 11. zermatt.csail.mit.edu 0.0% 12 23.1 23.1 23.1 23.3 0.1

Windows versions WinMTR is a Windows GUI application functionally equivalent to MTR. It was originally developed by Appnor MSP S.R.L.; it is now maintained by White-Tiger. Although it is very similar, WinMTR shares no common code with MTR. A console version of MTR does exist for Windows, but it has fewer features than MTR on other platforms.

Similar commands Windows NT and beyond has a built-in PathPing command that similarly combines the functionality of ping with that of tracert. It displays network latency and network loss at intermediate hops between a source and destination. Because it displays the degree of packet loss at any given router or link, it can also be used to determine which routers or subnets might be having network problems.

Worked examples

Example 1 — a first encounter with MTR (software)

Start with the simplest possible case. Write down what MTR (software) claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to MTR (software) before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about MTR (software) ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of MTR (software)

In research: MTR (software) appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses MTR (software) in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: MTR (software) is common in secondary-school and first-year university syllabi. It links to neighbouring topics Free network-related software, Network analyzers, so understanding it makes those chapters shorter.
In everyday life: Look for MTR (software) outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study MTR (software) in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what MTR (software) means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain MTR (software) out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is MTR (software) in simple terms?

Why does MTR (software) matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study MTR (software)?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on MTR (software).