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

[Richard Mortimer]

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.

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
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> 
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