Zen Internet Support Forum

I have a few pc's, now they mostly use XP pro because thats what I am most familiar with, however I do run vista 32 and vista 64 and win7 64.

Their is something I have noticed with the different OS's

From a fresh install on all rigs, from XP Pro - Win7, that all my XP rigs get a steady speed of 850-870kbs download, roughly 6.7 - 6.8mbps, I have seen it slightly higher but it is always steady in the 860kb range, now on all my Vista rigs and win7 whether thats 32bit or 64, my speeds are a constant 960 - 980kbs which is 7.5mbps.

Is my speed being displayed wrongly in the vista and win7 rigs ? because I thought the max an 8mbit line could get was 7.1mbps which due to overheads we are never gunna be able to get the full 7100kbits ps in download speed. 

I do know that vista has changes to the way it handles network connections than it does in XP, but surely that cannot account for a faster than 8meg line speeds ?

So anyone got any ideas why in XP I get roughly the max of what is capable on an 8meg line but in vista and win 7 I get way beyond what is supposedly capable on an 8 meg line.

I am not worried, I am just curious asto why on a different OS my speeds arent just higher, but higher by atleast 100kbytes which isnt to be sniffed at, is the vista and 7 rigs showing the wrong speeds or are they correct ?  because I was happy with 860kb on xp but I didnt think I could get nearly 1000kbps just by changing OS's

Hello Evil-Scotsman,

I have an XP Pro SP3 rig and a Vista home premium SP2 rig. OK! the difference as I understand this is that in windows XP you have to set the MTU & RWIN values in networking settings (i.e. TCP/IP settings) to get the best through put from your DSL line.  Taking into account the router or modem settings too.

**in Windows vista and windows 7 both the MTU & RWIN settings are auto adjusted by the OS itself in order to give you the maximum through put from your DSL connection. Vista & Win7 have been more optimized by Microsoft with digital subscriber line in mind were XP wasn't tuned as well.

**DSL performance is subject to a large number of variables though not just the OS itself. For example:- distance from the nearest BT phone exchange, quality of the actual cabling, line noise & line attenuation, contention ratios, time of day, type of router or modem, internet traffic flows locally, internet traffic internationally etc.

**No very few people ever see a full 8megs on BT's present DSL Max product as you say this is due to the TCP/IP overheads. Its the connection overheads that guarentee the data is sent & recieved all in tact, if not the packets are re-transmitted anyway. 

Ivan

Thanks for replying Cyteck,

 

I realise that rwin is auto adjusted in vista and win 7, but what I was more interested in and maybe I should of phrased it differently is, the max theoretical speed anyone can get on an 8mbit line is 7150kbps and that includes overheads, and its very unlikely anyone will get the full 7150kbps download speeds due to the overheads being calculated in amongst the 7150 figure and roughly 6900 is the fastest a person on an 8mbit line will see when downloading.

What is confusing me is, why is vista and win 7 showing my download speeds as being stable in the 7500 - 7700kbps aka 7.7mbps which is far in excess of the theoretical max of 7150, as I thought 7150 was the very fastest one could attain due to the bras profile and even then, they wouldnt get the full 7150 whilst downloading due to the overheads.

As I say, I prefer this speed if its showing it properly, because its adding on a minimum of 100kbs extra onto my previous max speed on xp of 860kbps, so I am now hitting nearly 1000kbps stable, when I thought that that should not be possible due to profiling.

So my question is, why I am getting far in excess of the 7150 bras profile, is vista and win7 showing the wrong speeds or is BT/Zen actually allowing me to get those speeds in excess of the theoretical 7150kbps maximum limit, because its basically an extra 1/2meg I am getting if my OS's are correct to which I am not sure if they are and I am really curious to see if I really am getting 7.7mbps which 3 different OS's claim.

 

Cheers

How are you actually measuring your speeds?

Just by downloading big downloads from usenet, which is usually spot on.

On my xp rigs, when downloading via usenet which maxes out my connection all the time regardless of OS used, my download speed shown at the bottom of newsbin pro is the same as what speedtest websites show for my download throughput, that also includes BT speedtester website.

So I have no real reason to think that the same version of newsbin pro used on a different OS would feed me such results if they were wrong ? then again maybe it would ? I dunno.

 

 

Does downloading large test files (eg the ones at http://fuller.zen.co.uk/test/ ) replicate your results for speed?

If so I can only assume that some mtu/rwin tweaking must be required on the slower computers (see http://www.dslreports.com/tweaks )

---

Kindest regards,

James Sweet
http://www.zen.co.uk

I have figured out what the problem is, I was reading newsbin forums today and I came across this buried in a thread that has nothing to do with speed.

 

"Newsbin has tradionally under-reported its download speed. For the 5.53 release the algorithm for calculating speed was tweaked to try and bring it in-line with what Task Manager reports. Unfortunately that means the apparent speed increase is not a real one."

 

So that would account for the increase in speed that I am seeing in newsbin, because I was using XP 32 with the previous version of news bin before and when I installed Vista 64 I was forced to ditch the version of newsbin that I had and had to download the 64b version which as mentioned above contains a tweak to "bring the speed in line with what TM reports", but even that is wrong because task manager on my rig always reports no higher than 870kbps in xp and vista whilst newsbin was reporting 970kbps.

I guess that my speeds are still the same, maybe a few KB faster in vista but nowhere near the 100kb + that newsbin reports, I will admit I didnt think newsbin would report such corrupt figures as newsbin has always been bang on with my correct speeds, and with the upgrade to vista I just assumed that it was vista that was the culprit, but obviously not and the tweak that newsbin got for version 553 is obviously showing the wrong speeds, although I am still able to download at the same rate as with xp, because downloads dont take any longer than before, maybe slightly faster, but not 100kbs+ faster.

The only accurate way is to download the same big file and use a stopwatch timer. You ned to repeat the exercise making sure that you eliminated any effects due to caching or different workloads on the server.