Fibre are fastest today from FTTC

I have noticed my FTTC has gone fastest ever. Has Openreach tweak FTTC?

https://www.thinkbroadband.com/speedtest/15683775836...

False alarm. The speedtest are unreliable one from thinkbroadband.

The speedtest.net are spot on correct. https://www.speedtest.net/result/8586871506

Yes false alarm as other tests you ran a few minutes later look good http://tbb.st/1568378133191149355

There was a spike in some of the others at the start http://tbb.st/1568377969588391055 but the figures come out reasonable, i.e. efforts to mitigate the occasional burst at the start due to browsers/anti virus software etc do work but are not 100% bullet proof.

An interesting observation is that when there is the spike there is also increased average latency too, so something was probably happening on the connection/PC

I have disabled anti virus and got this speed spot on

https://www.thinkbroadband.com/speedtest/15684055032...

Do you really have nothing better to do?

In reply to a post by CarlTSpeak:

Do you really have nothing better to do?

REF: Speedtest.net

When I use this I get silly results as it connects to IBM about 1 mile away. Not a true indication of real world internet.

Used to use a american service which has since been withdrawn, you could connect to servers that were used for the Winter Olympics, at about 4k miles that was a true test. It was fibre, via Berlin and then the trans atlantic cable to the US then fibre to the server.

In reply to a post by bigluap:

REF: Speedtest.net

When I use this I get silly results as it connects to IBM about 1 mile away. Not a true indication of real world internet.

Used to use a american service which has since been withdrawn, you could connect to servers that were used for the Winter Olympics, at about 4k miles that was a true test. It was fibre, via Berlin and then the trans atlantic cable to the US then fibre to the server.

I'm going to go out on a limb here and suggest it's unlikely that you are connecting to that server a kilometre away via anything like a direct route.

With the modern Internet the vast majority of the content you're consuming is probably being fed to you by content delivery networks within the British Isles.

speedtest.net and similar are not fed from CDN, but are direct streams from a selected remote server.

speedtest.net is designed to make your ISP look good. It does this by (a) choosing a server with the smallest Round Trip Time, and (b) opening 6 TCP streams in parallel.

The maximum achievable throughput you can achieve on a single TCP stream is very sensitive to RTT and packet loss. The formula is here.

On a LAN with 1ms RTT, even packet loss as high as 1% is barely noticable. A single TCP stream would have its throughput limited to:

1460 / (0.001 * sqrt(0.01)) * 8 = 116.8 Mbps

But on a connection with a 100ms round-trip time, even packet loss as low as 0.01% (1 packet in 10,000) will limit a TCP stream to one tenth of that speed, i.e. 11.68Mbps. To match it, you would need packet loss of 0.0001% (1 packet in a million)

Each TCP stream reacts to packet loss independently though, so six TCP streams together can use of six times as much bandwidth.

Thanks for that. I didn't suggest speedtest.net uses a CDN and wide area network performance, including things like considering BDP, are my day job but appreciate it.