[Cerowrt-devel] cerowrt-3.10.2-1 dev release + owamp
Fred Stratton
fredstratton at imap.cc
Sat Aug 3 06:36:13 EDT 2013
I cannot currently access the gateway device.
AFAIK, Cerowrt does not allow setting up a masquerade, and it is physically difficult to access. I wish I could have a masquerade. The device has a fixed IP address of 192.168.1.254.
The target snr is set high, so the device does not retrain for months, so the line speed remains constant. The ISP I use has been sold by Telefonica to Sky, who use a fixed 7.5 target snr, so this stability may go. I may change ISPs to overcome this.
The device is a bridged 2wire 2700, which provides a frequency graph. This looked normal.
When I used a Broadcom based router, and TomatoUSB -shibby - I could access the device and run RouterStats in a wine bottle. The interference occurs at 0700 and 0200 every day. I have had the street lights serviced. Chain saws are a problem. Aldi or Lidl sell cheap chain saws which are not well suppressed electrically and cause random interference.
I use a VDSL grade NTE, with large line chokes, shielded cables. and ferrite rings on the input phone line. All phones are DECT.
The problem with a liberal Telecoms market is that there is only one Wholesale provider, OpenReach. They will not investigate anything other than voice line faults. The phone lines and cabinets are over 60 years old.
I am sure the 2700 is part of the problem. However other choices, like a Thomson TG585v7, are associated with similar uplink delays. and does not hold the line as well. despite its Broadcom SoC - the DSLAM is an Ericsson, which returns BRCM.
I mention all this on list not just to answer your question, but to describe a fairly typical situation. The majority of users obtain internet service over a land line., these days via ASDL2+. I have a liberal telecoms market, can swap around the equipment II have attached to a typical phone line perfectly legally to optimise the signal I receive. Boxes like the 2wire and Thomson TG585v7 are what ISPs provide. Cerowrt should at some point allow the ADSL user to surf the web and download at the same time.
On 3 Aug 2013, at 10:38, Sebastian Moeller <moeller0 at gmx.de> wrote:
> Hi Fred,
>
>
> On Aug 1, 2013, at 00:35 , Fred Stratton <fredstratton at imap.cc> wrote:
>
>>
>> On 31 Jul 2013, at 23:14, Sebastian Moeller <moeller0 at gmx.de> wrote:
>>
>>> Hi Fred,
>>>
>>> thanks a lot.
>>>
>>>
>>> On Jul 31, 2013, at 23:37 , Fred Stratton <fredstratton at imap.cc> wrote:
>>>
>>>> tc -s -d class show dev ge00
>>>>
>>>> class htb 1:10 parent 1:1 leaf 110: prio 0 quantum 1500 rate 700000bit ceil 700000bit burst 1599b/1 mpu 0b overhead 0b cburst 1599b/1 mpu 0b overhead 0b level 0
>>>> Sent 15809014 bytes 115190 pkt (dropped 4733, overlimits 0 requeues 0)
>>>> rate 3616bit 3pps backlog 0b 0p requeues 0
>>>> lended: 115190 borrowed: 0 giants: 0
>>>> tokens: 263560 ctokens: 263560
>>>>
>>>> class htb 1:1 root rate 700000bit ceil 700000bit burst 1599b/1 mpu 0b overhead 0b cburst 1599b/1 mpu 0b overhead 0b level 7
>>>> Sent 15809014 bytes 115190 pkt (dropped 0, overlimits 0 requeues 0)
>>>> rate 3616bit 3pps backlog 0b 0p requeues 0
>>>> lended: 0 borrowed: 0 giants: 0
>>>> tokens: 263560 ctokens: 263560
>>>>
>>>> class fq_codel 110:1b8 parent 110:
>>>> (dropped 0, overlimits 0 requeues 0)
>>>> backlog 0b 0p requeues 0
>>>> deficit 84 count 0 lastcount 0 delay 10us
>>>>
>>>>
>>>>
>>>> tc -s -d class show dev ifb0
>>>> class htb 1:10 parent 1:1 leaf 110: prio 0 quantum 1500 rate 7000Kbit ceil 7000Kbit burst 1598b/1 mpu 0b overhead 0b cburst 1598b/1 mpu 0b overhead 0b level 0
>>>> Sent 192992612 bytes 168503 pkt (dropped 0, overlimits 0 requeues 0)
>>>> rate 17096bit 4pps backlog 0b 0p requeues 0
>>>> lended: 168503 borrowed: 0 giants: 0
>>>> tokens: 27454 ctokens: 27454
>>>>
>>>> class htb 1:1 root rate 7000Kbit ceil 7000Kbit burst 1598b/1 mpu 0b overhead 0b cburst 1598b/1 mpu 0b overhead 0b level 7
>>>> Sent 192992612 bytes 168503 pkt (dropped 0, overlimits 0 requeues 0)
>>>> rate 17096bit 4pps backlog 0b 0p requeues 0
>>>> lended: 0 borrowed: 0 giants: 0
>>>> tokens: 27454 ctokens: 27454
>>>>
>>>> class fq_codel 110:cc parent 110:
>>>> (dropped 10, overlimits 0 requeues 0)
>>>> backlog 0b 0p requeues 0
>>>> deficit -198 count 1 lastcount 1 ldelay 2.3ms
>>>> class fq_codel 110:1d9 parent 110:
>>>> (dropped 0, overlimits 0 requeues 0)
>>>> backlog 0b 0p requeues 0
>>>> deficit 226 count 0 lastcount 0 ldelay 2us
>>>> class fq_codel 110:1de parent 110:
>>>> (dropped 0, overlimits 0 requeues 0)
>>>> backlog 0b 0p requeues 0
>>>> deficit 238 count 0 lastcount 0 ldelay 10us
>>>> class fq_codel 110:345 parent 110:
>>>> (dropped 0, overlimits 0 requeues 0)
>>>> backlog 0b 0p requeues 0
>>>> deficit 226 count 0 lastcount 0 delay 9us
>>>>
>>>> I changed the hard coded values in /usr/lib/aqm/functions.sh to arbitrary values, rebooted and obtained the same results. Both reflect the 7000kbit/s down and 700kbit/s up I entered in the window.
>>>
>>> What is the line rate as read out from the del modem or specified in your contract?
>>
>> Speedtest.net shows the rate as circa 8.7 megabits/s down, 1 megabit/s up. Line has radio frequency interference from unidentified sources..
>
> So it looks like specify a generous reserve for the shaper. Can you log into your modem and get the current line rates? The rf interference, is it constant (if you can get nice SNR per sub carrier or even ust bit loading per frequency plots) that is does it only affect the same frequencies or does it change? (I ask, because temporary interference might reduce the effective line rate, potentially moving the buffer back into the del modem)
>
>> Target snr upped to 12 deciBel. Line can sustain 10 megabits/s with repeated loss of sync.at lower snr. Contract is for 'up to 20megabits/s'.
>
> So ADSL2+ as you even mentioned it before.
>
>> 850 metres from exchange. Line length circa 1.2km.
>
>
>
>>
>>
>>>
>>>> I ticked the adsl box. Altering the value in functions.sh and unticking the box, with reboot, produced the same outcome.
>>>
>>> This nicely shows I screwed up my testing (and or forgot to reboot between changes). Or I did try too high a data rate (initially 97% of the raw link rate)
>>>
>>>
>>>>
>>>>
>>>>
>>>> traceroute google.com
>>>> traceroute: Warning: google.com has multiple addresses; using 173.194.41.128
>>>> traceroute to google.com (173.194.41.128), 64 hops max, 52 byte packets
>>>> 1 172.30.42.1 (172.30.42.1) 0.631 ms 0.323 ms 0.249 ms
>>>> 2 * * *
>>>> 3 10.1.3.234 (10.1.3.234) 22.596 ms 21.241 ms 22.392 ms
>>>> 4 * 10.1.3.214 (10.1.3.214) 27.018 ms 26.703 ms
>>>> 5 10.1.4.249 (10.1.4.249) 29.682 ms 28.923 ms 27.479 ms
>>>> 6 * * *
>>>> 7 * 209.85.252.186 (209.85.252.186) 30.379 ms *
>>>> 8 72.14.238.55 (72.14.238.55) 25.745 ms 25.345 ms 25.594 ms
>>>> 9 lhr08s03-in-f0.1e100.net (173.194.41.128) 27.566 ms 27.390 ms 27.663 ms
>>>>
>>>> mtr shows packet losses at hops 2-5
>>>> 10.1.3.* are Internet Watch Foundation.
>>>
>>> This looks pretty reasonable for an adsl link (could be way worse with higher interleaving)
>>>
>>>>
>>>> Netalyzr was used. I appreciate it is an imperfect metric.
>>
>> OK. Like the ping train idea. Cannot get netperf 2.6.0 to build on Ubuntu 12.04
>
> So I typically run a 1000 count ping against the nearest host that is on the other side of the DSL link that also gives consistent ping RTTs without load. Then I start my test loads like saturating the upload with a long runnig TCP transfer and opening 99 media heavy tabs in a browser (I really should try the chrome benchmark that Dave is using). And the I simply look through the ping statistic results, typically I look at the maximum, and at the standard deviation to get a handle on how tight the shaper held latency under control. (If I should get netperf-wrapper to work under Macosx I will try to use that for testing, but it does not even install, and if I get past that hurdle I will have to adjust for the differences between Gnu ping and BSD ping).
>
>
> Best Regards
> Sebastian
>
>
>>>
>>> Well, I ran into this issue before. In short netalyzr's worst case delay numbers do not seem to reflect how an fq_codelled connection feels.
>>> Netalyzr uses an unresponsive UDP probe to force the bottleneck router's buffers to fill up; with unresponsiveness being a property no sane flow over the intent should exhibit. Codel/fq_codel is tailored for responsive flows and will only gradually increase its drop frequency so responsive TCP flows will be controlled gently and keep link utilization high. Given enough time codel will also rein in an unresponsive flows. But netalyzr's probe duration is too short for that to be happening during netalyzr's runtime.
>>> Fq_codel in my experience does a decent job at keeping interactivity high even with competing traffic like netalyzr (so turn a ping train against say 10.1.3.234 while netalyzr runs or try netperf-wrapper in addition).
>>> So netalyzr really probes the worst case buffer depth against basically a "denial of service" type of load; I am not fully sure what the expectancy on the disc here should be.
>>>
>>>
>>> best
>>> Sebastian
>>>
>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> On 31 Jul 2013, at 21:38, Sebastian Moeller <moeller0 at gmx.de> wrote:
>>>>
>>>>> tc -s -d class show dev ge00
>>>>
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>>>
>>
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>
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