Why 307

I had an Openreach WBC FTTP 330/50 connection installed at the beginning of November, during the last month I have performed many speeds tests both wired and wireless, but the fastest I have ever managed in off-peak times is 307 Mbps. My original estimate from BT Retail was 313 Mbps, so it's not like there is any issues, but I wonder why it's not the full 330 on a FTTP connection?

What factors (apart from network congestion) actually lead to a FTTP connection not running at full speed?

Out of interest, does the upstream always give a tad over 50 ?

Nope, it's pretty much 49 all the time

In reply to a post by bedrock:

Ok I wonder why it's not the full 330 on a FTTP connection?

330 Mb/s will be the �sync� speed, after overheads you will get around 310 Mb/s. If you�re getting in excess of 300 Mb/s in Speedtests you�ve got nothing to worry about

Somewhat odd, all those I�ve tested get a shade over the upload.

In reply to a post by baby_frogmella:

In reply to a post by bedrock:

Ok I wonder why it's not the full 330 on a FTTP connection?

330 Mb/s will be the �sync� speed, after overheads you will get around 310 Mb/s. If you�re getting in excess of 300 Mb/s in Speedtests you�ve got nothing to worry about

I totally agree, just did a few tests as I do now and then and yes its about those speeds.

[IPv4]


[IPv6]


[Ookla Speedtest]
https://www.speedtest.net/result/7871866050

Speed tests were done while others here were using the internet like watching Twitch or YouTube etc.

Those speeds are at that speed 24 / 7

What was strange was when we were on Infinity 4 (300:30) we did see the odd faster speed, however the average speed was all over the place, where as with Ultrafast 2 Plus we get a stable max speed.

Paul

I'm not worried, just intrigued

In reply to a post by Zarjaz:

Somewhat odd, all those I�ve tested get a shade over the upload.

I do, I get about 300 to 309Mbps downstream and around 52 to 53Mbps upstream.

Paul

I did try with Linksys router and that did go just over 50, but not with the BT Smarthub

Thanks

The speedtest client can only see the user data, not the encapsulation overhead.

An ethernet frame carries 1500 bytes payload, and is about 1536 bytes total by the time you add ethernet headers and framing.

If you are using PPPoE (without baby jumbos) then that's 8 bytes taken, leaving a 1492 byte MTU.

A 1492 byte IP datagram used for TCP carries 1444 bytes of user data (20 bytes IP header + 28 bytes TCP header, including TCP timestamp option)

So of the raw 330Mbps stream, the rate of user data carried is 330*(1444/1536) =~ 310Mbps

..... and what was the download speed with the Linksys ?

Thank you very much, that definitely answers my question

I don't recall it being any different, so it went straight back to Amazon, sorry I can't answer the question in a quantifiable way.