Yes, basic divide and conquer. Various ways to slice and dice it ... e.g. by function (Bandwidth? Latency? Connectivity? DNS?), location (segment(s) or portion(s) along the way), equipment (substitution of computer(s)/cable(s), connectivity location(s), etc.
Essentially work to isolate what/where the problem is. Eventually one gets it narrowed to exactly what/where it is, at which point the fix is generally obvious, or one isolates it to so-and-so's or such-and-such's responsibility, and then they can fix their broken portion.
From: "Christian Einfeldt" <einfe...@gmail.com> Subject: Re: [Ubuntu-US-CA] Internet slowdown Date: Fri, 24 Jun 2016 20:51:06 -0700
Thanks to everyone who replied to this thread. I am going to be going back to the homeless shelter soon, and I will update everyone after following the suggestions given in this thread. Thanks! On Fri, Jun 24, 2016 at 8:31 PM, Mark Weisler <m...@weisler-saratoga-ca.us> wrote:Hi Christian, I'm intentionally top posting... As a general practice, you want to engage in "bracketing" to try to isolate your networking problem. You know that you have a problem all the way out at the end computer in the lobby. Now you want to take a notebook computer to the "first place" you have an internet connection at the site. This is probably at the broadband modem or as close to the demarcation point as possible. Assuming you have an ethernet cable connecting from the broadband router to your switch, take a "known good" ethernet jumper cable and plug one end into the broadband modem (or dsl modem) and the other into your notebook. Test the internet connection from there. If bad or flaky or slow you then know to call the ISP. (Probably after rebooting all the electronics and testing again.) If good, then disconnect your notebook and connect the broadband modem to the switch. Pick a suitable port on the "LAN side" of the switch and test again. If good you probably know the switch is good. Perform another test on the port serving the lobby of the establishment to learn if maybe that particular port is bad but others are good. It sometimes happens that a port on the "LAN side" of the switch is bad, maybe just one out of N ports, and you can just plug the lobby line into a different (good) port. If the port serving the lobby has been good and tests good then you know you probably have a problem with the cabling between the switch and the lobby "technology outlet". And so on. Bracketing your testing to isolate what is good and what is not. There are, of course ways to use electronics to test and measure the quality of the ethernet cables installed in the building. It can sometimes be good to have all this testing and documented as a baseline for your records but maybe that's not affordable in this situation. Hope that helps. On Jun 24, 2016, at 12:20 PM, Christian Einfeldt wrote: Hi, Here are my questions: 1. Why did my speed tests fail in this situation? 2. Are the ping speeds normal for this situation? 3. What diagnostic tests can I run to isolate the slowness on this system? As most people on this list know, Partimus is volunteering for a low income housing shelter in here in SF. I have put in some quality legacy Lubuntu machines in the lobby for the residents to use. These machines all have Intel Core 2 duo chips with 2 GB of RAM and are running Lubuntu 14.04. I use a similar machine at home, and have no problems with it. This email is being written on such a machine at one of the other two homeless shelters. The residents routinely use these machines to watch YouTube video and use LibreOffice, etc., all without issue. The machines are proven good. This is the third shelter to which we have given machines. They don't have a budget for either the equipment or the tech support for these machines. Two of the three shelters have good speed on the Internet that goes to the machines. (The shelters provide the Internet service). However, the third shelter, called the Mentone, has slow Internet speeds in the lobby. I am not able to even do anything as basic as run sudo apt-get update, as the machine chokes on downloading the updates. The wiring is put in place by a company I will call the Maintenance Group (MG). I have called both the MG and the ISP. Both of them claim that they have no problems. The ISP says that they are providing the usual 2 Mbit / second that we expect here in the US for a configuration like this. The MG says that they have run a test on the wiring from the server to the lobby, and are not seeing any problems. The ISP is a good company that does not hate GNU-Linux. The ISP asked me to give them a speed test directly from the switch, which is located in the basement. So I ran speed tests in the basement and in the lobby, and was unable to get the speed test to work. Speed test has worked on this machine before. Here are the two results: Lobby, where the Lubuntu machine is to be located: cje@cje-ultralap440:~$ speedtest-cli Retrieving speedtest.net configuration... Could not retrieve speedtest.net configuration: timed out cje@cje-ultralap440:~$ ifconfig eth0 Link encap:Ethernet HWaddr 20:1a:06:04:64:42 inet addr:172.16.2.121 basement, directly from the switch: cje@cje-ultralap440:~$ speedtest-cli Retrieving speedtest.net configuration... Could not retrieve speedtest.net configuration: timed out cje@cje-ultralap440:~$ *My first question: *I am not sure why this speed test failed. Does anyone know? Since I couldn't run speedtest, I pinged google instead. Here are the results from the lobby: cje@cje-ultralap440:~$ ping www.google.com PING www.google.com (216.58.192.4) 56(84) bytes of data. 64 bytes from nuq04s29-in-f4.1e100.net (216.58.192.4): icmp_seq=1 ttl=52 time=8.24 ms 64 bytes from nuq04s29-in-f4.1e100.net (216.58.192.4): icmp_seq=2 ttl=52 time=7.31 ms <snip> --- www.google.com ping statistics --- 16 packets transmitted, 12 received, 25% packet loss, time 15037ms rtt min/avg/max/mdev = 6.962/7.497/8.198/0.366 ms Here is the test from the basement: cje@cje-ultralap440:~$ ping www.google.com PING www.google.com (216.58.192.4) 56(84) bytes of data. 64 bytes from nuq04s29-in-f4.1e100.net (216.58.192.4): icmp_seq=1 ttl=52 time=8.24 ms 64 bytes from nuq04s29-in-f4.1e100.net (216.58.192.4): icmp_seq=2 ttl=52 time=7.31 ms <snip> --- www.google.com ping statistics --- 11 packets transmitted, 11 received, 0% packet loss, time 10015ms rtt min/avg/max/mdev = 7.022/7.816/8.519/0.451 ms cje@cje-ultralap440:~$ *My second question*: Are these ping speeds normal? My third question: What can I do to find the problem with the system? Thanks! -- Christian Einfeldt -- Ubuntu-us-ca mailing list Ubuntu-us-ca@lists.ubuntu.com Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-us-ca -- Mark Weisler 'This message has been signed using strong encryption for your protection.' PGP Key ID 68E462B6 PGP Key fingerprint 87D5 A77B FC47 3CC3 DFF0 586D 23FF F8B4 68E4 62B6 -- Ubuntu-us-ca mailing list Ubuntu-us-ca@lists.ubuntu.com Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-us-ca-- Christian Einfeldt
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