Question regarding speeds

Hi all.

Having finally got my ADSL up and running, looking at the diagnostic
entries in the telnet system of my 510v4 router, the down and up speeds of
the router are 576 and 288k respectively (1358 and 679 cells).

I thought that the down and up speeds were only 512k and 256k. Even if 1k
= 1024, this doesn't correspond to 512 or 256. What gives?

I'm also impressed with my attenuation. 24 down and 11 up!

Pete.

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"Pete Smith" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> Hi all.
>
> Having finally got my ADSL up and running, looking at the diagnostic
> entries in the telnet system of my 510v4 router, the down and up speeds of
> the router are 576 and 288k respectively (1358 and 679 cells).
>
> I thought that the down and up speeds were only 512k and 256k. Even if 1k
> = 1024, this doesn't correspond to 512 or 256. What gives?

Try running a speed test at http://www.adslguide.org.uk/tools/speedtest.asp

> Having finally got my ADSL up and running, looking at the diagnostic
> entries in the telnet system of my 510v4 router, the down and up speeds
> of the router are 576 and 288k respectively (1358 and 679 cells).
>
> I thought that the down and up speeds were only 512k and 256k.

There is an ADSL overhead in each frame sent (IIRC for each 40 bytes, there
are an extra 5 bytes of overhead data) - thus, the connection speed always
looks higher than it actually is - but if you take the connection speed,
divide by 45, then multiply by 40, you should get your actual maximum
download speed.

In article <Gx6ub.9510$(E-Mail Removed)>,
(E-Mail Removed) says...
> > Having finally got my ADSL up and running, looking at the diagnostic
> > entries in the telnet system of my 510v4 router, the down and up speeds
> > of the router are 576 and 288k respectively (1358 and 679 cells).
> >
> > I thought that the down and up speeds were only 512k and 256k.
>
> There is an ADSL overhead in each frame sent (IIRC for each 40 bytes, there
> are an extra 5 bytes of overhead data) - thus, the connection speed always
> looks higher than it actually is - but if you take the connection speed,
> divide by 45, then multiply by 40, you should get your actual maximum
> download speed.

I see.

I didn't realise they'd included the overheads in that, and that the rate
you "buy" is the end-to-end data transfer rate, rather than the bit rate.

The 40/45 rule is a handy one.

Thanks,

Pete.

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Pete Smith <(E-Mail Removed)> wrote:

: I didn't realise they'd included the overheads in that, and that the rate
: you "buy" is the end-to-end data transfer rate, rather than the bit rate.

The rate you "buy" is 512k. Its some routers which report the higher "raw"
rate of ~576k.
Even with 512k user protocols like ftp add their own overhead and file
transfers will typically max out at 59-60k on compressed files.

In article <bpb66e$(E-Mail Removed)>, (E-Mail Removed)
says...
> Pete Smith <(E-Mail Removed)> wrote:
>
> : I didn't realise they'd included the overheads in that, and that the rate
> : you "buy" is the end-to-end data transfer rate, rather than the bit rate.
>
> The rate you "buy" is 512k. Its some routers which report the higher "raw"
> rate of ~576k.
> Even with 512k user protocols like ftp add their own overhead and file
> transfers will typically max out at 59-60k on compressed files.

That's what I've found today.

Absolutely gutted that it took 4 hours to download the 760Mb Steam
installation file :-)

The odd thing is that it doesn't matter how fast a connection is, it
always seems too slow! It took 4 minutes to download 13Mb, and I was
thinking "Come on, haven't you finished yet?"!

Pete.

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Pete Smith wrote:

> In article <Gx6ub.9510$(E-Mail Removed)>,
> (E-Mail Removed) says...
> > > Having finally got my ADSL up and running, looking at the diagnostic
> > > entries in the telnet system of my 510v4 router, the down and up
> > > speeds
> > > of the router are 576 and 288k respectively (1358 and 679 cells).
> > >
> > > I thought that the down and up speeds were only 512k and 256k.
> >
> > There is an ADSL overhead in each frame sent (IIRC for each 40 bytes,
> > there are an extra 5 bytes of overhead data) - thus, the connection
> > speed always looks higher than it actually is - but if you take the
> > connection speed, divide by 45, then multiply by 40, you should get your
> > actual maximum download speed.
>
> I see.
>
> I didn't realise they'd included the overheads in that, and that the rate
> you "buy" is the end-to-end data transfer rate, rather than the bit rate.
>
> The 40/45 rule is a handy one.

I don't think that's right each packet seems to get 10 added to it's IP
size, is then padded to fit an exact number of ATM cells each of which is
48 byte data and 5 header.

This is why 1478 or 1430 are better MTUs than 1500 or 1458 as they don't
waste half a cell per packet.

Andy.

In article <(E-Mail Removed)>,
(E-Mail Removed) (Pete Smith) wrote:

> That's what I've found today.
>
> Absolutely gutted that it took 4 hours to download the 760Mb Steam
> installation file :-)
>

bummer when that happens innit ! :-(
- Steve

In article <(E-Mail Removed)>,
(E-Mail Removed) says...
> In article <(E-Mail Removed)>,
> (E-Mail Removed) (Pete Smith) wrote:
>
> > That's what I've found today.
> >
> > Absolutely gutted that it took 4 hours to download the 760Mb Steam
> > installation file :-)
> >
>
> bummer when that happens innit ! :-(

Totally :-)

Beats the day and a bit it would have been, if I'd still been on Home
Highway :-)

Pete.

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