Disconnections during downloads

[Ignitionnet]

While heavily using the connection for a period the Nokia 7750-SR I talk to at Wakefield exchange seems to like disconnecting me for no apparent reason.

32542 2020/149 21:35:12.303 f8:13:08:40:ef:24 Ubiquiti_5b:15:81 PPP LCP 60 Termination Request

This is a little unnecessary given the LCP echo and response were 5 seconds beforehand, another cycle wasn't due for a further 5 seconds:

32136 2020/149 21:35:07.744 Ubiquiti_5b:15:81 f8:13:08:40:ef:24 PPP LCP 30 Echo Request
32137 2020/149 21:35:07.750 f8:13:08:40:ef:24 Ubiquiti_5b:15:81 PPP LCP 60 Echo Reply

Can't see anything my kit sent that would've caused the SR to decide to kill the LCP session. Would welcome anyone's thoughts.

[pippincp]

Hi Carl, thought you were in Leeds?

I presume you've done the usual, connected to the test socket and quiet line test? 17070 option 2.

[Ignitionnet]

Sorry.

This is FTTP. Issues with copper unlikely 🙂

C

[Ignitionnet]

Okay.

This is nothing to do with losing the PHY link - so FTTP/VDSL irrelevant. Not losing connection with exchange, Openreach section is fine.

I connect to acc-aln2.wk.21cn-infra.bt.net via Openreach OLT BAADXE.

So far so normal.

However, when I use the service for large downloads the Nokia 7750 seems to like disconnecting me for no apparent reason.

I've a switch in between my router and the Openreach ONT and was able to capture the PPPoE session. The 7750 seems to be dropping traffic initially on a per-flow basis, I see the heavy flow abruptly stop, with bits of intermittent downstream traffic arriving and of course upstream traffic from me as my kit responds to what it perceives as loss.

LCP echoes carry on as normal despite IP traffic virtually halting. Nothing out of the ordinary at all, and these are being sent and responded to at 10 second intervals with correct sequence and session details:

31824 21:34:57.734 Ubiquiti_5b:15:81 f8:13:08:40:ef:24 PPP LCP 30 Echo Request

31829 21:34:57.741 f8:13:08:40:ef:24 Ubiquiti_5b:15:81 PPP LCP 60 Echo Reply
32136 21:35:07.744 Ubiquiti_5b:15:81 f8:13:08:40:ef:24 PPP LCP 30 Echo Request

32137 21:35:07.750 f8:13:08:40:ef:24 Ubiquiti_5b:15:81 PPP LCP 60 Echo Reply

Within 5 seconds of this, however, the Nokia sends an LCP Termination Request

32542 21:35:12.303 f8:13:08:40:ef:24 Ubiquiti_5b:15:81 PPP LCP 60 Termination Request

I see nothing coming from my kit to trigger this. The session is being kept alive as normal and I can't see anything in the Openreach SINs indicating their OLT could trigger this.

I could speculate on all kinds of things but cant see anything that could be causing this on my side so am left with an issue on BTW.

The PPPoE session promptly re-establishes normally and smoothly, though of course all pre-existing connections have to be rebuilt due to change of public IP so it's noticeable. Also triggers failover to 4G which isn't great.

Not sure what else I can add, and not sure what the community can tell me but I was admonished to reach out to the community and welcome feedback.

[pippincp]

To be honest I cannot see the community being much help with this. I think it might even be above the FTTP team but you could give them a try. 0800 587 4787

[Ignitionnet]

Need someone at BT Wholesale really with access to the 7750.

I can, of course, pull strings, but wanted to do this the right way. Following the process of community, social media team, etc.

[Ignitionnet]

Definitely a BT Wholesale issue. The first thoughts were the right ones and subsequent tests proved it out .

Seriously doubt I'll ever be told what the issue is but hopefully won't happen to anyone else. 

[pippincp]

I would never doubt your netwok knowledge, perhaps pulling strings is the only way you'll get it resolved. Thanks for keeping us updated.

[Ignitionnet · Accepted solution]

Flattering as that is complacency and failure to carry out appropriate diligence is a very direct route to missing something and looking ridiculous.

Thanks. 

[pippincp]

Carl, you forget this is a customer supprorted forum  and I have known of you for over 15yrs. I wasn't flattering you but acknowledging what I know about you.

If the issue is in the ONT then it is something BT Retail has no control over.

Take care.

Pip