The newer modem supports the bonding of more download channels (8 vs. 4 for the 6120) and is also used in conjunction with telephony (whereas I have a pure Internet subscription without telephony). Anyway, all of that should not matter as you also indicate: both can handle the respective up- and download speeds with ease. <br>
<br>Yes, both she and I have the same subscription (minus the telephony): 60 Mb down and 4 Mb up. We also only live 25 kilometres apart (small country:-))<br>The uplink speed is mostly consistent around 3.76 megabit. I've never caught our cable company going lower than 3.50 megabit in the upload direction and I've done a lot of speedtests. The only limit I have been able to observe is in the download direction when their network is really busy.<br>
<br>I guess I will have to venture into traffic shaping. (I'll probably loose a lot of sleep setting this up lol). Is there any way to determine the buffer size reliably?<br><br><div class="gmail_quote">On Sat, Feb 9, 2013 at 7:15 PM, Jonathan Morton <span dir="ltr"><<a href="mailto:chromatix99@gmail.com" target="_blank">chromatix99@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><p>Latency caused by bufferbloat always appears at the bottleneck device. Usually that is the modem, and you've given no alternative that it could plausibly be. The modems you mention are slightly different model numbers, but that can hide substantial differences in internal configuration. </p>
<p>For a typical drop-tail queue, the induced latency under load is the size of the buffer divided by the speed of the link draining it. Assuming both modems have a 4Mbit uplink, 550ms is consistent with a 256KB buffer, and 220ms is consistent with a 48KB buffer - neither of which would seem excessively large to a modem builder who hasn't heard of bufferbloat. However with a shared cable infrastructure, it is possible that the uplink is constrained by other users on the same segment, which will skew this calculation. </p>
<p>To cure it without modifying the modem, you need to move the bottleneck to a point where you can control the buffer. You do this by introducing traffic shaping at slightly below the advertised modem uplink speed on one of your own machines and directing all upstream traffic through it. </p>
<span class="HOEnZb"><font color="#888888">
<p> - Jonathan Morton<br>
</p>
</font></span><div class="gmail_quote"><div><div class="h5">On Feb 9, 2013 7:27 PM, "Forums1000" <<a href="mailto:forums1000@gmail.com" target="_blank">forums1000@gmail.com</a>> wrote:<br type="attribution">
</div></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div class="h5">
Hi Jonathan and Dave<br><br>My entire LAN-network is gigabit. My cable subscription is 60 megabit down and 4 megabit up. <br>Now, both my routers' WAN-port and the cable modems' LAN port are also gigabit. The router can route LAN to WAN and the other way around (with NAT and connection tracking enabled) in excess of 100 megabit. <br>
<br>Now my cable modem is a Motorola Surfboard SV6120E and hers is a Motorola Surfboard CV6181E. My upload lag is 550ms and hers is only 220ms. Moreover, at her place there are Powerplugs in the path limiting her download to 30 megabit instead of 60 megabit. Yet, the upload lag is much lower than mine. There, it also did not matter where I ran Natalyzr, the result was always 220ms of bufferbload.<br>
<br>Could this still be only the modem?<br><br><br><div class="gmail_quote">On Sat, Feb 9, 2013 at 10:52 AM, Forums1000 <span dir="ltr"><<a href="mailto:forums1000@gmail.com" target="_blank">forums1000@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hi everyone,<br><br>Can anyone give some tips on how to diagnose the sources of bufferbloat? According to the Netalyzr test at <a href="http://netalyzr.icsi.berkeley.edu/" target="_blank">http://netalyzr.icsi.berkeley.edu/</a>, I have 550ms of upload bufferbloat. I tried all kinds of stuff on my Windows 7 laptop:<br>
<br>- For the Intel(R) 82567LF Gigabit Network Connection, I put receive and transmit buffers to the lowest value of 80 (80 bytes? 80 packets? I don't know). I also disabled interrupt moderation. <br>Result? Still 550ms.<br>
- Then I connected my laptop directly to my cable modem, bypassing my Mikrotik 450G router. Result? Still 550ms of bufferbloat. <br>- Then I put a 100 megabit switch between the cable modem an the laptop (as both cable modem and Intel NIC are gigabit). Result? Still 550ms of upload bufferbloat.<br>
<br>I'm out of ideas now. It seems I can't do anything at all to lower bufferbloat. Or the Netalyzr test is broken?:-)<br><br>many thanks for your advice,<br>Jeroen<br><br>
</blockquote></div><br>
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