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  • It's the network, really

    April 17, 2009

    In my 2009 OFCNFOEC conference report, I reported the words of Philippe Morin of Nortel Canada, who told conference attendees that "the economic downturn is actually accelerating bandwidth growth because people are staying home and they want their entertainment delivered."

    I believe him. Here’s why.

    Recently, I’ve noticed that my home DSL line gets slow in the evenings. It came to a head one Sunday evening when I wanted to listen to an online audio stream of a broadcast that started at 8:00 PM. The stream would last for a few seconds, then stop for many seconds–perhaps minutes–then start again. Sometimes, the connection to the server would be lost and my computer would have to reconnect.

    I called tech support at my DSL provider, a local ISP who leases the line from Verizon. (At least when you call, you get a local person.) The technican told me that they would monitor the line for the next 24 hours. I called again and was told that I had line problems and that needed repair. The following day, someone from my ISP called (that was nice of them) said that line had been reconfigured and was now running at 1 Mbps. When I got home that evening, I tried a speed test. It ran at about 600 kbps. Not as good as I was told, but enough to download e-mail. That was at 6:00 PM. At 8:00 pm, the speed was down to about 200 kbps and at 10:00 the DSL line was unusable. I was trying to download 2 MB of emails and found it faster to switch to dialup. The dialup was slow, but the data came down at a consistent rate. When using the DSL line, the model would receive data in short bursts, then stop for several minutes.

    At midnight, the line once again ran at 1 Mbps. My conclusion: its the network, not my DSL line. Some online hamework told me that this is common. In the hours from 4:00 to 10:00 pm, people are downloading videos and music, clogging the network. Now, I find that I need to get online before 7:30 or after 11:00 to get any decent speed. I may do any downloading in the morning, when speeds are fast.

    I’ll keep a running log here of download speeds and events

    On April 21, my download speed was 979 kbps at 6:00 pm, 200 kbps at 8:00 pm, 70 kbps at 9:00 pm, and essentially zero at 10:00 pm. Simple web pages took 10 minutes to download at that time.

    April 22: Called ISP, A Verizon tech came to the house and tested the line outside. No problems found. I expected that, but In edd to prove that it’s not my line. House is 15,200 ft. from the central office.
    Evening of April 22, pretty much the same results.

    April 23
    : working at home today. Here are some test results. I’ll update throughout the day
    9:00 am, 1074 kbps (Proof that the DSL is capable of reaching the claimed speed of 1 Mbps.)

    April 23: Verizon ran a test at 9:00 pm. The report said somethingabout latency. No surprise there. Technican coming to my house on Aril 24.

    April 24: A Verizon technician came to my house to test the 15,000-ft. DSL line from my house to the central office. As expected, he proved that the line can handle 1 Mbps download speeds.

    April 25: Didn’t get on the net until after 11 pm. Watched preview videos for the new Star Trek movie. Video streams worked well, but only after 11:30.

    April 27: I have the attention of my local ISP. A representative called me to say that they were continuing to monitor my uploads and downloads. They need test speed numbers to report to Verizon on the line perormance.

    April 28: Tried a different test. I uploaded a 4.1 MB mp3 file to my ISP’s server, then downloaded it multiple times. at 8:00 pm, the download took 33 seconds at a download speed of about 970 kbps. An hour later, the download times out after 14 minutes. I tried again several times betwnn 9:00 and 10:00 with the same results. At 11:30, the same download took just over 2 minutes with a download speed of about 200 kbps. At 8:00 am on April 29, the download time was back to 33 seconds.

    April 29: A technican at the ISP told me that other customers on the same PVC (permanent virtual circuit) are experiencing the same problems with download speeds in the evening.

    April 30: Ran the download test again. At 7:45 pm, download time was 33 seconds. At 8:53 pm, the download duration increased to 1:15. At 9:02 pm, the time increased dramatically, to over six minutes. Download time remained in the 5-6 minute range for about an hour, then gradually decreased back to 33 seconds by 11:30.

    Posted by Martin Rowe on April 17, 2009 | Comments (1)
    Industries: Communications Test
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  • April 21, 2009
    In response to: It's the network, really
    Neal Roche Ixia commented:

    Hi Martin, Aah, the mystery of network slowdowns… First up I think your conclusion is correct; it’s the network not your DSL line. We often look at the DSL line speed as the prime suspect when our internet service slows down. However the bottleneck could be in a number of places. I was surprised when I heard from some major Service providers that they don’t know why their internet service is slow! Here is a quick list of the components: - your home network, - the xDSL link - the aggregation network from the remote DSLAM to a major POP, - the Service provider transport to the Internet gateway router, - the internet path to the content provider - the Application Server in the content provider When you ran a speed test at an off-peak time you got good throughput so I think you’re home network and DSL link is fine. More than likely, the backhaul link from your local DSLAM to a major internet POP is oversubscribed up to 20 times! Perhaps you and 20 of your neighbors are sharing a single T1 at peak times. The best solution for Service providers is to use active monitoring which can isolate network bottlenecks by sending test traffic across their networks. They can do this remotely and judge when they need to provision more bandwidth in their access networks. Ixia provides a solution called IxRave which can do active monitoring. If I were you I would contact your ISP and use the speed test results to demonstrate that they need to add more network bandwidth. Neal Roche

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