I've mentioned before that the packet-loss graph being on a different axis is counter-intuitive and confusing.

If your backup software was busy between 10:30pm and 1:15am doing lots of uploading e.g. using 2 Mbps out of 2 Mbps of upload capacity that you have then

1. I would expect average latency to increase dramatically
2. Some packet loss as routers prioritise your traffic rather than our little ping, which probably gets responded to beyond the 500ms we consider a packet lost at.

Resyncs usually are shown as a period of solid red from top to bottom, as we get zero response during the 30 seconds to a minute this takes. So unless your ADSL modems are able to resync in just 2 to 3 seconds then I'd suggest that the graph is NOT showing a total loss of connection for that period, but a heavily utilised connection.

http://www.thinkbroadband.com/ping/monitors/graph/57... 9pm to midnight on there was me uploading a Gigabyte or more of data. No packet loss, but this varies from router to router, and not sure of how the bonded solution would impact things.

The ISP should have the connection sync history.

BQM is designed as a latency monitoring system, and packet loss detection, but knowing what is happening on the line and in the ISP is very important. We know some users who also set up a BQM to the first hop on their ISP network, to help understand when ISP congestion is an issue.

In reply to a post by MrSaffron:

If your backup software was busy between 10:30pm and 1:15am doing lots of uploading e.g. using 2 Mbps out of 2 Mbps of upload capacity that you have then

1. I would expect average latency to increase dramatically
2. Some packet loss as routers prioritise your traffic rather than our little ping, which probably gets responded to beyond the 500ms we consider a packet lost at.

And yet in the five or six years that's been running we don't normally see that kind of packet loss. Also the process started about half an hour into that outage and normally runs for up to three hours (it's pushing stuff in both directions to sychronize folders between sites.

That chunk of red/blue is not due to the synch process. It's something else that started before the sync, pretty much killed the synch (I think it gave up at about 3%).

In reply to a post by BatBoy:

I've mentioned before that the packet-loss graph being on a different axis is counter-intuitive and confusing.

Perhaps it is but I keep an eye on the graphs as part of my job and in my experience when the red lines meet and overlap the blue lines it means there's a problem. I don't know exactly what it means from a technical POV but I do know that when they do that anyone trying to access the internet or another office will be out of luck. I also know that normally they are few and far between (maybe one a week) but when we get migrated onto 21CN they increase to half a dozen or more every day and are often prolonged outages rather than a quick bounce.

Time will tell but I'm pretty sure that once we're put back on 20CN the red lines will be nothing more than a few pixels at the top of the image.

Blood drips. It doesn't levitate.

And without access to the sync data for the two modems and trying things like turning one off we cannot be sure the issue is NOT ADSL2+ related or the WBC network.

Can your provider not remotely manage the routers to force ADSL only mode on them? This would cure almost all issues where the line was not handling the extra bit loading from ADSL2+ very well, if that is what it is.

Hmm. Is this a problem whose nature is being masked by the bonding?

What is the likelihood that, when one line resyncs, the other does so at the same moment?

If one line resyncs alone, then what happens to the ICMP packets? Are 50% routed to the wrong modem, and lost forever? Or is the routing smart enough so it appears like (just) a loss of 50% capacity?

Either way, a sync on one of the lines is not going to look the same, on the TBB graphs, as "standard" broadband.

@Andrue: What happens when you deliberately turn one modem off, and leave things running on the other one? Has this been tried before?

In reply to a post by Andrue:

Perhaps it is but I keep an eye on the graphs as part of my job

Er, nice job. I prefer f8lure as it handles dynamic IP's, the graphs are on the same axis and you don't get the long grass obscuring the view.

I doubt it's proper bonding using G.Bond as 21CN was never supposed to work bonded. What is it, Sharedband?

In reply to a post by MrSaffron:

Which means the issue may be nothing to do with 21CN ADSL2+ but more to do with the WBC backhaul network and how the ISP manages the traffic/volumes it purchases etc

If latency performance is critical to business then its reconsider the bonded solution and look at the Ethernet options. Very little in the way of latency SLA for WBC.

dont be too quick to blame wiring issues, I certianly dont trust stats provided by openreach.

My experience was this.

adsl1, flaky but ran ok when heavily buffed up with high SNR.
adsl2, same as adsl1 without SRA, with SRA it ran much better and could work on lower SNR.
adsl2+, a disaster, much lower sync than adsl1/2 although with SRA still it wasnt less stable just a much lower sync speed.

I tried various routers, netgear dg384GT (sky router) broadcom 7402s (new and old types), speedtouch 585v4 and a couple of others. All were worse on adsl2+ than adsl2.

With all this said tho, I expect any adsl2+ service to allow people to force an adsl1 or adsl2 connection ie. backwards compatible, I could force adsl1 on ukonline and I could on xilo as well.

So to the OP assuming 21CN allows the router to overide the modulation mode Ithen you will be ok.