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110 lines
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110 lines
4.2 KiB
Plaintext
Some details about echoping
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echoping is a debugging tool. It is not a "end user" tool. For
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instance, HTTP testing takes host names, not URLs as parameters (if
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you want to test in a more HTTPish way, use wget). Also, when
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connecting to a server which has both IPv4 and IPv6 addresses,
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echoping does not try every address in turn like most user-oriented
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programs do. If you want to test only the IPv4 address, use the
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address, not the host name (or use the -4 option).
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echo service:
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echoping assumes the remote host accepts such connections. Experience
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show that most Internet routers do and many hosts also. However, some
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Unices are not shipped with this service enabled and, anyway, the
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administrator is always free to close it (I think they
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shouldn't). echoping has therefore less chance to succeed than ping or
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bing. (On a typical Unix box, "echo" service is configured in
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/etc/inetd.conf but see the CERT advisory
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<http://www.cert.org/advisories/CA-96.01.UDP_service_denial.html>.)
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What does it measure?
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echoping simply shows the elapsed time, including the time to set up
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the TCP connection and to transfer the data (but excluding the time
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for the - possible - DNS call). Therefore, it is unsuitable to
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physical line raw throughput measures (unlike bing). On the other end,
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the action it performs are close from a HTTP request and it is
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meaningful to use it (carefully) to measure Web performances.
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UDP and inetd:
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With UDP servers you can have surprises: the first test is quite often
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much slower since inetd has to launch the process. After that, the
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process stays a while so the next texts run faster.
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A nice example:
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There are many, many traps when measuring something on the
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Internet. Just one example: 'echoping -w 0 -n 4 a-sunOS-machine' and
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you'll see the first test succeed in a very short time (if you are
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close from the machine) and all of the others take a much longer time
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(one second). With '-w 1' (wait one second between tests, the
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default), everything works fine: it seems the sockets on SunOS need
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time to recover :-)
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To measure performances on the Internet you can also see:
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Unix:
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- bing, a bandwidth measurement tool <ftp://ftp.lip6.fr/pub/networking>
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- ping, probably available with your system
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- traceroute, idem (otherwise, see <ftp://ftp.ee.lbl.gov/>)
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- ttcp, the best measurement tool but it needs some control over the
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two machines <ftp://ftp.arl.mil/pub/ttcp> (nothing to do with
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the T/TCP protocol)
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- treno (evaluates available bandwidth for TCP)
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<http://www.psc.edu/~pscnoc/treno_info.html>
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- spray is a tool which I dont't know very well. It is available on some
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machines (Sun, OSF/1).
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I've also heard of but never tried:
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- the very good mon program <http://www.kernel.org/software/mon/> includes a
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up_rtt.monitor which has many similarities with echoping
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- NetPerf <http://www.netperf.org/netperf/NetperfPage.html>
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- a suite of Bandwidth Measuring programs from gnn@netcom.com
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<ftp://ftp.netcom.com/~ftp/gnn/bwmeas-0.3.tar.Z>. These are several
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programs that measure bandwidth and jitter over several kinds of
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IPC links, including TCP and UDP.
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Macintosh:
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- TCP Watcher, a very nice "swiss-army knife" tool, to test ping, DNS, echo.
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It includes an echo server. Available on Info-Mac in "comm/tcp".
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MS-Windows:
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(I have little knowledge of that environment and I tested nothing.)
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- WSNUTIL. Seems to be an echo client and server.
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<http://www.ccs.org/winsock/xref-e.html#echo_clients>
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- echox32. An echo server.
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<http://www.winsite.com/info/pc/win95/misc/echox32.zip/>
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- cfinger. An echo client and server.
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<http://www.winsite.com/info/pc/win3/winsock/cfing13b.zip/>
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Windows-NT :
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echo and other services can (apparently) be provided within 'Simple
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TCP/IP Services' which can be enabled through the Network Control
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Panel
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Web clients:
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- You can ping or traceroute on the Web. See
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<http://www.freenix.org/cgi-bin/traceroute.iphtml>,
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<http://www.tracert.com/> or
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<http://www.fr.net/internet/trace.html>.
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Use all of them with care, the result is not obvious to interpret.
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And don't forget to read RFC 1470 ("Tools for Monitoring and Debugging
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TCP/IP Internets and Interconnected Devices"), specially its
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"Benchmark" section and the W. Richard Stevens' books (all of them),
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published by Addison-Wesley.
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$Id$
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