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Author Topic: High packet loss and occasional disconnection under load  (Read 1397 times)

leonroy

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Re: High packet loss and occasional disconnection under load
« Reply #15 on: October 31, 2019, 01:18:04 PM »

Swapped over to the Zen provided Fritz!Box 7530 and seeing the same issue with dropped packets on saturating the line.

https://en.avm.de/products/fritzbox/fritzbox-7530/

Similar dropped packets whilst trying to ping outside:
Code: [Select]
64 bytes from 8.8.8.8: icmp_seq=504 ttl=54 time=4.535 ms
64 bytes from 8.8.8.8: icmp_seq=505 ttl=54 time=4.577 ms
64 bytes from 8.8.8.8: icmp_seq=506 ttl=54 time=15.606 ms
64 bytes from 8.8.8.8: icmp_seq=507 ttl=54 time=16.302 ms
64 bytes from 8.8.8.8: icmp_seq=508 ttl=54 time=4.061 ms
Request timeout for icmp_seq 509
64 bytes from 8.8.8.8: icmp_seq=510 ttl=54 time=17.556 ms
Request timeout for icmp_seq 511
64 bytes from 8.8.8.8: icmp_seq=512 ttl=54 time=17.713 ms
64 bytes from 8.8.8.8: icmp_seq=513 ttl=54 time=4.612 ms
64 bytes from 8.8.8.8: icmp_seq=514 ttl=54 time=17.352 ms
64 bytes from 8.8.8.8: icmp_seq=515 ttl=54 time=16.380 ms

Pinging the router (unlike pfSense) is fine though:
Code: [Select]
64 bytes from 10.1.0.2: icmp_seq=81 ttl=64 time=0.593 ms
64 bytes from 10.1.0.2: icmp_seq=82 ttl=64 time=0.673 ms
64 bytes from 10.1.0.2: icmp_seq=83 ttl=64 time=0.441 ms
64 bytes from 10.1.0.2: icmp_seq=84 ttl=64 time=0.576 ms

BQM graph (last bit) indicates:


It's supposed to handle speeds up to 300Mbps so wondering what on earth could be the cause. Unless the Fritz!Box is similarly afflicted?

« Last Edit: October 31, 2019, 01:35:40 PM by leonroy »
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dee.jay

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Re: High packet loss and occasional disconnection under load
« Reply #16 on: October 31, 2019, 01:42:52 PM »

I would doubt highly it would be affected the same way. Looks like you have ruled out your original hardware, because the issue is still present.
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Chrysalis

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Re: High packet loss and occasional disconnection under load
« Reply #17 on: October 31, 2019, 02:14:37 PM »

Even tho you have not solved it, for the reasons dee jay said this is progress as you have now determined it is present after changing the CPE.

So this could be perhaps related to the way either zen or openreach (or BTw if BTw backhaul) queue traffic.

A way round that would be to shape below your maximum throughput so the bottleneck is moved to your network and then have higher control over the queuing of packets, the problem is this is harder to do on ingress.  ISP's like aaisp give you control over what they rate limit the traffic at to mitigate downstream packet loss issues.

What type of service is the download been carried out on?  Things like steam are horrible as they effectively DDOS the end user's line on a download with how high threaded the download is.
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leonroy

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Re: High packet loss and occasional disconnection under load
« Reply #18 on: October 31, 2019, 02:28:08 PM »

There's a setting the Fritz!Box router to reduce the line speed:


I've dropped it from 338/51 to 300/45. Same issue though, BQM is reporting dropped packets.

ISP is Zen and the package is Zen Fibre 4.

Don't suppose it could be the Huawei MT992 modem?
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kitz

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Re: High packet loss and occasional disconnection under load
« Reply #19 on: November 04, 2019, 02:37:30 AM »

I saw this the other day and thought surely if the link is under extreme high load then there is the possibility of dropped packets, but I don't know enough about settings on that particular router etc to be able to contribute anything useful.

Jelv & Weaver are actually correct...  the ISP is supposed to rate limit to match the IP profile or line rate, but the only ISP's where we have seen evidence of them doing this is with AAISP and Plusnet.

It's several years ago now since I read the docs, but from memory basically it is both to stop bottle necks on the BTw backhaul and also to help reduce the possibility of dropped {ATM} packets at the DSLAM.   eg if the download is coming down the backhaul at say 1Gbps (or multi Gbps) and suddenly is restricted to say xDSL 10Mbps DSL then you can end up with a bottleneck and dropped packets at that point.   I don't know if this also applies to G.fast, but certainly it was documented for FTTC and ADSL.    I'd need to do some research and double check if its something to do with ATM or not before I start chipping in my 2p. 

The takeup rate for g.fast is  quite low...  if he is sharing a BTw backhaul with only a couple of g.fast connections then he possibly has a nice big fat pipe practically to himself right up to the OLT.    BTw only police the amount of bandwidth traffic passing through the ISP host link and not the speed - which is why they recommend the ISP rate limits before downstream traffic hits their backhauls.
I dont know how the IP profile for g.fast works... or even if there is one but presumably there must be.   

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ETA   can't find the documentation right now..  searching brings me to here

https://kitz.co.uk/adsl/IPprofile.htm#why_IP_bRAS_profile   :lol:
« Last Edit: November 04, 2019, 03:04:56 AM by kitz »
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leonroy

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Re: High packet loss and occasional disconnection under load
« Reply #20 on: November 08, 2019, 09:33:25 AM »

Thanks, appreciate the feedback from all here.

Just an update on my own findings. I kept a note of the IP of the Zen gateway so was able to tell when it changes. Some Zen gateways seem to be less reliable than others, right now it's working well.

My test to create packet drops might be partly responsible; I was downloading a bunch of little files across many SSL connections. This test reliably causes 9-16% packet loss and lost pings to 8.8.8.8.

However when I download a single big file like an ISO from a single host I get zero packet loss and zero lost pings.

Both tests saturate the pipe.

Some more discussion here:
https://forum.netgate.com/topic/147820/acceptable-packet-loss-on-wan/14

Will report back if I notice anything new.
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Chrysalis

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Re: High packet loss and occasional disconnection under load
« Reply #21 on: November 08, 2019, 09:24:00 PM »

yeah thats no surprise, the little files test will have a higher packets per second, and its pps thats really the measure of a network appliance.
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kitz

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Re: High packet loss and occasional disconnection under load
« Reply #22 on: November 10, 2019, 07:47:10 PM »

Had another thought which I cant see mentioned.   Buffer bloat?
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leonroy

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Re: High packet loss and occasional disconnection under load
« Reply #23 on: November 11, 2019, 10:05:54 AM »

Had another thought which I cant see mentioned.   Buffer bloat?

Can do subnet calculations in my head (just about ;D) but first I've heard of buffer bloat, live and learn.



Full results:
https://www.dslreports.com/speedtest/56309497

No packet loss reported in pfSense on the WAN side during the test.
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