[OpenWrt-Devel] Frequent adsl disconnections with BTHOMEHUBV2B (lantiq xway danube)

[Sebastian Moeller]

Hi Richard, hi Jaime


On Nov 17, 2014, at 12:33 , Richard Mortimer <richm+openwrt at oldelvet.org.uk> wrote:

> Hi,
> 
> On 15/11/2014 10:40, Jaime T wrote:
>> Hi all.
>> 
>> I'm running "barrier breaker" (r42625) on a BTHOMEHUBV2B and it's
>> great apart from frequent adsl disconnections (approx 40 per day). My
>> adsl-type is POTS so the relevant part of /etc/config/network is:
>> 
>> config adsl 'dsl'
>>        option annex 'a2p'
>>        option firmware '/lib/firmware/adsl.bin'
>> 
>> Each disconnection puts approximately the following into the syslog:
>> 
>> Fri Nov 14 09:33:41 2014 daemon.info pppd[1218]: No response to 5 echo-requests
> 
> I think I saw something similar when I was using an ADSL connection.
> 
> When the connection was under full load (I don't remember whether it was
> upstream, downstream or both) the LCP echo requests that PPPD does seem
> to get dropped somewhere in the ADSL infrastructure. The link is however
> working fine passing "real" traffic.
> 
> You can test this fairly easily by generating a lot of traffic that
> lasts over 5 seconds and it will cause the connection to drop. Then try
> increasing the lcp-echo-failure value in /etc/ppp/options and observing
> whether the download continues after 5 seconds.

	After changing the pop values have a look at the output of “ps w” on the router, when I tried to p;ay with these from the luci GUI I noticed that pppd was called with lcp-echo-failure 5 while the GUI reported 0 (meaning unlimited), so something might be off in parsing/passing the arguments from the GUI. (Then again with my testing I nave managed to get pop session timeout even though packet captures indicated that under load some lcl echo requests went missing…)

Best Regards
	Sebastian


> 
> Gentoo have a patch that adds a lcp-echo-adaptive option to pppd. This
> treats traffic receipt as equivalent to receiving an lcp echo-reply.
> http://sources.gentoo.org/cgi-bin/viewvc.cgi/gentoo/src/patchsets/ppp/2.4.5/34_all_lcp-echo-adaptive.patch
> 
> I did very briefly test with that patch and it seemed to work but I
> moved onto another connection before I'd convinced myself that it really
> was appropriate.
> 
> Regards
> 
> Richard
> 
>> Fri Nov 14 09:33:41 2014 daemon.notice pppd[1218]: Serial link appears
>> to be disconnected.
>> Fri Nov 14 09:33:41 2014 daemon.info pppd[1218]: Connect time 28.9 minutes.
>> Fri Nov 14 09:33:41 2014 daemon.info pppd[1218]: Sent 554487 bytes,
>> received 6119357 bytes.
>> Fri Nov 14 09:33:41 2014 daemon.notice netifd: Network device
>> 'pppoa-wan' link is down
>> Fri Nov 14 09:33:41 2014 daemon.notice netifd: Interface 'wan' has
>> lost the connection
>> Fri Nov 14 09:33:47 2014 daemon.notice pppd[1218]: Connection terminated.
>> Fri Nov 14 09:33:47 2014 daemon.notice pppd[1218]: Modem hangup
>> Fri Nov 14 09:33:58 2014 kern.warn kernel: [ 1832.784000] leave showtime
>> Fri Nov 14 09:33:59 2014 daemon.info pppd[1218]: Terminating on signal 15
>> Fri Nov 14 09:33:59 2014 daemon.info pppd[1218]: Exit.
>> Fri Nov 14 09:33:59 2014 daemon.notice netifd: Interface 'wan' is now down
>> Fri Nov 14 09:34:27 2014 kern.err kernel: [ 1861.796000]
>> [DSL_BSP_Showtime 894]: Datarate US intl = 924903, fast = 0
>> Fri Nov 14 09:34:27 2014 kern.warn kernel: [ 1861.800000] enter
>> showtime, cell rate: 0 - 2181, 1 - 2181, xdata addr: 0x82b00000
>> Fri Nov 14 09:34:29 2014 daemon.notice netifd: Interface 'wan' is setting up now
>> 
>> My line stats are:
>> 
>> # /etc/init.d/dsl_control status
>> Chipset:                Ifx-Danube 1.3
>> Line State:             UP [0x801: showtime_tc_sync]
>> Data Rate:              7.040 Mb/s / 924 Kb/s
>> Line Attenuation:       37.4dB / 21.2dB
>> Noise Margin:           7.1dB / 10.0dB
>> Line Uptime:            25m 39s
>> 
>> The disconnections happen more frequently at night time. I have
>> several of these boxes, and they all exhibit the same behaviour so I
>> do not believe that it is a hardware problem specific to 1 router. I
>> also have the original "sky"-supplied router which does not suffer
>> from these disconnections.
>> 
>> The dsl connection appears to be a bit of a "black-box" - I can find
>> very little documentation discussing it, although 1 or 2 people have
>> mentioned XTU bits, which I don't understand.
>> 
>> Is there anything that I can modify to try to stop these
>> disconnections from happening? Would lowering the connection speed
>> help, and if so, can this be done?
>> 
>> All info/suggestions would be gratefully received. With kind regards,
>> 
>> Jaime
>> _______________________________________________
>> openwrt-devel mailing list
>> openwrt-devel at lists.openwrt.org
>> https://lists.openwrt.org/cgi-bin/mailman/listinfo/openwrt-devel
>> 
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