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Author Topic: unlocked hg612 with ADSL2+ - network stability issues  (Read 22042 times)

ejs

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Re: unlocked hg612 with ADSL2+ - network stability issues
« Reply #45 on: October 31, 2016, 06:43:42 PM »

Wait a minute, the ADSL line stats from the HG612 indicated you were connecting at the maximum possible 8128k / 448k on 20CN ADSL1. So improvements to things like the DSL cable shouldn't have made any difference, unless you think the slow throughput speeds are related to the amount of CRC errors, but you could check for things like that in the telnet stats from the HG612, or use a program such as DSLstats.
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JSHarris

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Re: unlocked hg612 with ADSL2+ - network stability issues
« Reply #46 on: October 31, 2016, 07:13:08 PM »

Yes, I did disable QoS.  The odd disparity between the ADSL line stats and the speeds reported by online speed checkers (and the speeds we seem to get in practice, judging from the buffering that goes on with things like YouTube video and iPlayer) remains a mystery.

I'm new to getting stats from the system, and have only just started at looking how to do it properly, so, in a few days time, perhaps, I should have a better ideas as to what is going on.

The most noticeable change I noticed after doing all the work today is that the characteristic of all the download tests I tried had changed, markedly.  Previously, I used to get a short period during the test at around 7 to 8 Mb, then a dip to zero, followed by a variable 2 to 3 Mb for the rest of the DL test.  Today, every test I tried showed a steady figure of around 4Mb, peaking to 5Mb, with none of the drop outs that I've always seen before.

Whether these drop outs were caused by either of the two modem/routers I had been using (for the past year I've been using a TP-Link TD-8817, but switched to the PhoneCoop provided Technicolor TG582N last week, to see if that made an improvement) I don't know.  I do know that the HG612 wouldn't work as a modem and router, no matter what I tried, but seems very solid when used as just a modem.

Hopefully I'll have some time to gather some stats properly before we get switched to VDSL on the 14th November, as I'm curious as to why there should be such a disparity between the reported line stats and reality.  I'm also curious as to why the consistent initially fairly fast (close to the max the line would support) speed would drop right off after a short time when I was using either of the other two modem/routers.

Jeremy
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jch

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Re: unlocked hg612 with ADSL2+ - network stability issues
« Reply #47 on: October 31, 2016, 09:27:14 PM »

Quote
I always thought that switches had very little impact on speeds, as long as there wasn't masses of contending traffic, but it seems that in my case the switch slows things right down for some reason.  I shall have to investigate further!
Just a thought about the speed degradation when your GigE switch is in the network.

The HG612 has only a 100MBps ethernet port. When you connect that to your PC, the PC's ethernet port works out that it is connected to a 100MBps peer so sets its local interface up accordingly.

When you connect the HG612 to a GigE switch and the PC to the switch, you'll probably have a 1Gbps eth link from PC to switch and a 100Mbps link from switch to HG612. When you run a performance test, the PC will fire data at the switch at 1Gbps rate but the switch is only able to forward it to the HG612 at 100Mbps. Even if the switch has some packet buffering (many don't) a performance test will quickly exhaust it and cause data loss in the switch.

Some switches and some ethernet hardware in PCs can do ethernet flow control which might help in some cases (both ethernet hardware interfaces must support it and agree to use it when each ethernet link is established). Even if your switch and PC use ethernet flow control, I think you'd still see suboptimal performance results.

To test this, you might try to force the PC's eth port to 100Mbps when connecting it to your switch to do the performance test.
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JSHarris

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Re: unlocked hg612 with ADSL2+ - network stability issues
« Reply #48 on: October 31, 2016, 09:56:54 PM »

That's an excellent point, as the tests I ran today had the HG612 as a modem connected to a router, and then one of the router ports connected to the test PC (which in reality is my Linux home server at the moment).  The switch wasn't in the test circuit, it was hooked up to another port on the router to feed the other stuff in the house.
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