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Author Topic: What dictates the speed you get ?  (Read 555 times)

sdawson35

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What dictates the speed you get ?
« on: May 13, 2021, 07:49:23 AM »

Hi All,

What actually dictates the real speed you get from your ISP ? - My "speed" according to my router seems fairly fixed at 40Mb (consistent across the Zxyel or Cisco), Im on an FTTC service and yet every ISP I go to tells me you "could" have up to 67Mb and yet when I sign up I am always never able to attain that speed and the ISP then tells me "Oh sorry but you are inside the minimum so thats okay".

Unfortunately Hockley in Essex is another one of BT's "Ignored and Forgotten" places so we are stuck with FTTC and an oversubscribed exchange (even my 4G work router will only get around 36Mb) - so 4g isn't a solution either.
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tubaman

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Re: What dictates the speed you get ?
« Reply #1 on: May 13, 2021, 08:11:10 AM »

For FTTC the router sync speed is dictated by the length and condition of the cable between you and the cabinet that you connect to. This will not change no matter which ISP you are using as it's the same physical piece of wire.
The download speed you actually get (as opposed to sync) will always be lower than the sync speed due to overheads in the system (error correction etc) and can also be affected by the capacity and usage of the backhaul connections. This second part can be better or worse between ISPs but generally the one that people complain about is the sync speed.
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BT FTTC 80/20 Huawei Cab - Zyxel VMG8924-B10A

Weaver

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Re: What dictates the speed you get ?
« Reply #2 on: May 13, 2021, 09:02:06 AM »

If thereís congestion, unlikely, then you might not get the full speed you expect. Also if there are corrupt or lost packets then these will need to be retransmitted if you are using TCP for example, so that will reduce the speed youíre getting across the internet.

Referring to what tubaman said about overheads, if you are on the G.INP retx high setting that will take away about 8% of your speed due to wasteful overhead, so you wonít be getting the full speed associated with your sync rate. Normally the true speed you get is about 97% of your sync rate. By Ďspeedí, I mean here, to be exact, IP PDU rate. Overhead due to IP headers, and usually TCP headers too, will need to be subtracted as well if you want to get the file transfer rate, ie TCP payload rate.
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tubaman

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Re: What dictates the speed you get ?
« Reply #3 on: May 13, 2021, 09:59:24 AM »

Forgot to mention the router chipset (BCM, Mediatek etc) which can also make a difference in sync speed. However as you've mentioned using a ZYxel router, most of which are BCM based, I doubt that is an issue here.
 :)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 
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BT FTTC 80/20 Huawei Cab - Zyxel VMG8924-B10A

meritez

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Re: What dictates the speed you get ?
« Reply #4 on: May 13, 2021, 12:28:24 PM »

Any chance of the dsl stats from the router?
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tiffy

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Re: What dictates the speed you get ?
« Reply #5 on: May 13, 2021, 02:53:56 PM »

Agree with all the opinions expressed, would also consider any possible issues that could exist with your local wiring, ie, connect modem/router directly to the master socket (test socket) which should disconnect all internal connections from the line assuming extensions exist and have been properly wired.

As "meritez" has commected, detailed modem stat's would make line analysis/performance much easier.
You mentioned an available ZyXEL modem/router, this should work well with DSLStats utility and run on Windows, Linux or Raspberry Pi platforms to collect line stat's.

With line monitoring in place the master socket test for example should immediatly show any "before & after" changes that might result and highlight or eliminate any internal wiring issues.
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Zen 40/10 - DSLStats/RPi3B - ZyXEL VMG1312-B10A Modem/VMG-3925-B10B Router Huawei Cab

Weaver

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Re: What dictates the speed you get ?
« Reply #6 on: May 13, 2021, 04:40:19 PM »

Especially if you donít have a machine that can run DSLStats, our own johnsonís custom firmware for ZyXEL modems is incredibly fine; it gives you detailed stats directly from the modem using http - a second small web server is installed in the modem and all you need to see the stats displays is a web browser. Iím not at all sure about using this firmware if you use the ZyXEL as a router rather than a straight modem only.
« Last Edit: May 13, 2021, 04:45:47 PM by Weaver »
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sdawson35

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Re: What dictates the speed you get ?
« Reply #7 on: May 13, 2021, 05:25:05 PM »

Hi All,

DSLStats doesn't work on either of my routers.

My router is plugged directly into my 5E master socket - there are no other sockets   
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meritez

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Re: What dictates the speed you get ?
« Reply #8 on: May 13, 2021, 05:32:20 PM »

Hi All,

DSLStats doesn't work on either of my routers.

My router is plugged directly into my 5E master socket - there are no other sockets

@sdawson35 which router models?
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sdawson35

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Re: What dictates the speed you get ?
« Reply #9 on: May 13, 2021, 06:00:19 PM »

XMG3927-B50A and Cisco ISR 1111 (although this belongs to work  - its on "test")
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