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ADSL numbers.

 
 
Crash
Guest
Posts: n/a
 
      01-25-2006
Greetings,

I am wondering how the speed reported by my ADSL modem (D-LINK DSL-504G) relates
to the rated speed of my ADSL service.

The speed from the modem is reported as:

Downstream: 4704 Kbps Upstream: 320 Kbps

I am on the Xtra Swift package (no longer sold) of 2 megs download 192K upload.

If Kbps = 1000 bits per second, 2 megs is in bytes and there are 8 bits per byte
then I should be getting around (2megs x 16000 Kbps downstream and (192K x
1536 Kbps upstream. Clearly my assumption is wrong here or I am being
severely short-changed 8-( The same principles apply if the package speed is
bits not bytes.

If Kbps = 1000 bytes per second then the reported speeds are double my package
entitlement.

I am aware that actual speed is very volatile and not likely to get anywhere
near the package speed but would like to know how to accurately compare these
numbers.

Crash.

 
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EMB
Guest
Posts: n/a
 
      01-26-2006
Crash wrote:
> Greetings,
>
> I am wondering how the speed reported by my ADSL modem (D-LINK DSL-504G)
> relates to the rated speed of my ADSL service.
>
> The speed from the modem is reported as:
>
> Downstream: 4704 Kbps Upstream: 320 Kbps
>
> I am on the Xtra Swift package (no longer sold) of 2 megs download 192K
> upload.


Xtra's Jetstream isn't rate limited by line speed (as opposed to UBS
which is). Xtra do their traffic shaping within their network instead.
The figures you are seeing are the maximum that you line can support.

--
EMB
 
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Enkidu
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Posts: n/a
 
      01-26-2006
Crash wrote:
> Greetings,
>
> I am wondering how the speed reported by my ADSL modem (D-LINK DSL-504G)
> relates to the rated speed of my ADSL service.
>
> The speed from the modem is reported as:
>
> Downstream: 4704 Kbps Upstream: 320 Kbps
>

The numbers are kilobits/sec

Cheers,

Cliff
 
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Steve
Guest
Posts: n/a
 
      01-26-2006
On Thu, 26 Jan 2006 11:13:12 +1300, Crash wrote:

> Greetings,
>
> I am wondering how the speed reported by my ADSL modem (D-LINK DSL-504G) relates
> to the rated speed of my ADSL service.
>
> The speed from the modem is reported as:
>
> Downstream: 4704 Kbps Upstream: 320 Kbps
>
> I am on the Xtra Swift package (no longer sold) of 2 megs download 192K upload.
>
> If Kbps = 1000 bits per second, 2 megs is in bytes and there are 8 bits per byte
> then I should be getting around (2megs x 16000 Kbps downstream and (192K x
> 1536 Kbps upstream. Clearly my assumption is wrong here or I am being
> severely short-changed 8-( The same principles apply if the package speed is
> bits not bytes.

No. 2meg = 2 megabits. With 8 bits + stop bits, in reality ou'll get
200+KBytes/sec max.
>
> If Kbps = 1000 bytes per second then the reported speeds are double my
> package entitlement.

The speeds are artificially limited at the exchange. What you;re seeing is
what the line is capable of.
>
> I am aware that actual speed is very volatile and not likely to get
> anywhere near the package speed but would like to know how to accurately
> compare these numbers.
>
> Crash.

The real downer is the uplink, which Telecom brought down from 256 to
128kbit ):
 
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Mark C
Guest
Posts: n/a
 
      01-26-2006
Steve <(E-Mail Removed)> wrote in
news(E-Mail Removed):

> On Thu, 26 Jan 2006 11:13:12 +1300, Crash wrote:
>
>> I am wondering how the speed reported by my ADSL modem (D-LINK
>> DSL-504G) relates to the rated speed of my ADSL service.
>>
>> The speed from the modem is reported as:
>>
>> Downstream: 4704 Kbps Upstream: 320 Kbps
>>
>> I am on the Xtra Swift package (no longer sold) of 2 megs
>> download 192K upload.
>>
>> If Kbps = 1000 bits per second, 2 megs is in bytes and there
>> are 8 bits per byte then I should be getting around (2megs x
>> 16000 Kbps downstream and (192K x
>> 1536 Kbps upstream. Clearly my assumption is wrong here or I
>> am being
>> severely short-changed 8-( The same principles apply if the
>> package speed is bits not bytes.

>
> No. 2meg = 2 megabits. With 8 bits + stop bits, in reality ou'll
> get 200+KBytes/sec max.


No, there are no stop bits; DSL is synchronous.

You'll get ~250 kbps.

There are TCP/IP framing bytes, ~40 bytes per packet (usual packet
size 1,500 bytes, containing 1,460 bytes of payload).
The TCP/IP framing bytes may or may not be included in the Telecom 2
mbps rate.

Mark
 
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Mark C
Guest
Posts: n/a
 
      01-26-2006
Steve <(E-Mail Removed)> wrote in
news(E-Mail Removed):

> On Thu, 26 Jan 2006 11:13:12 +1300, Crash wrote:
>
>> I am wondering how the speed reported by my ADSL modem (D-LINK
>> DSL-504G) relates to the rated speed of my ADSL service.
>>
>> The speed from the modem is reported as:
>>
>> Downstream: 4704 Kbps Upstream: 320 Kbps
>>
>> I am on the Xtra Swift package (no longer sold) of 2 megs
>> download 192K upload.
>>
>> If Kbps = 1000 bits per second, 2 megs is in bytes and there
>> are 8 bits per byte then I should be getting around (2megs x
>> 16000 Kbps downstream and (192K x
>> 1536 Kbps upstream. Clearly my assumption is wrong here or I
>> am being
>> severely short-changed 8-( The same principles apply if the
>> package speed is bits not bytes.

>
> No. 2meg = 2 megabits. With 8 bits + stop bits, in reality ou'll
> get 200+KBytes/sec max.


No, there are no stop bits; DSL is synchronous.

You'll get ~250 kBps.

There are TCP/IP framing bytes, ~40 bytes per packet (usual packet
size 1,500 bytes, containing 1,460 bytes of payload).
The TCP/IP framing bytes may or may not be included in the Telecom 2
mbps rate.

Mark


 
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Mark C
Guest
Posts: n/a
 
      01-26-2006
Mark C <(E-Mail Removed)> wrote in
news:43d89abc$0$1586$(E-Mail Removed):

> You'll get ~250 kbps.


Sorry, I meant ~250 kBytes/sec
 
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Stephen Worthington
Guest
Posts: n/a
 
      01-26-2006
On Thu, 26 Jan 2006 20:37:07 +1300, Steve <(E-Mail Removed)> wrote:

>On Thu, 26 Jan 2006 11:13:12 +1300, Crash wrote:
>
>> Greetings,
>>
>> I am wondering how the speed reported by my ADSL modem (D-LINK DSL-504G) relates
>> to the rated speed of my ADSL service.
>>
>> The speed from the modem is reported as:
>>
>> Downstream: 4704 Kbps Upstream: 320 Kbps
>>
>> I am on the Xtra Swift package (no longer sold) of 2 megs download 192K upload.
>>
>> If Kbps = 1000 bits per second, 2 megs is in bytes and there are 8 bits per byte
>> then I should be getting around (2megs x 16000 Kbps downstream and (192K x
>> 1536 Kbps upstream. Clearly my assumption is wrong here or I am being
>> severely short-changed 8-( The same principles apply if the package speed is
>> bits not bytes.

>No. 2meg = 2 megabits. With 8 bits + stop bits, in reality ou'll get
>200+KBytes/sec max.


No stop bits. It is a PPP over ATM over ADSL connection, not an
asynchronous connection. Even dial-up modem connections are
synchronous now.

My real-life 2 Mibit/s UBS (Ihug) connection gives me 256 Kibytes/s of
TCP/IP bandwidth. To get your actual download bandwidth, you have to
take off the TCP/IP overheads from that and also the overheads for the
protocol you are using (eg HTTP, FTP, NNTP). But the ATM and PPP
overheads are not counted in the 2 Mibit/s - the PPP connection is
done so that you are delivered a full 2 Mibit/s by PPP.

>> If Kbps = 1000 bytes per second then the reported speeds are double my
>> package entitlement.

>The speeds are artificially limited at the exchange. What you;re seeing is
>what the line is capable of.


Yes, Telecom has what they call a "rate file" which lists each
connection and what speed it should have. The speed is limited by the
router that the rate file is loaded on. When I was on a 128 Kibit/s
Jetstream Starter connection via Telecom, I had a couple of faults
where they had to change the line card I was connected to at the
exchange. Each time that happened, until the new rate file was
automatically sent to the routers well after midnight, I got the full
ADSL bandwidth, which was over 4 Mibit/s in my case, very similar to
what Crash's modem is reporting for his connection.

I am not sure if Crash's modem is using K = 1024 or K = 1000 (the
latter most probably), but in any case those are normally the raw ADSL
speed available, after which you have to take off the ATM and PPP
protocol overheads to get the available TCP/IP bandwidth. And "bps"
in this case clearly means "bits per second" - if it was bytes, the
figures would be larger than standard ADSL can support, even
theoretically.

>> I am aware that actual speed is very volatile and not likely to get
>> anywhere near the package speed but would like to know how to accurately
>> compare these numbers.
>>
>> Crash.

>The real downer is the uplink, which Telecom brought down from 256 to
>128kbit ):

 
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~misfit~
Guest
Posts: n/a
 
      01-26-2006
Mark C wrote:
> No, there are no stop bits; DSL is synchronous.
>
> You'll get ~250 kBps.


I can vouch for that. With my Orcon 2M plan sometimes, when downloading from
HTTP sites, I sometimes get a consistant 256kB/s. (I have DU Meter running,
graphical representation "always on top").
--
~misfit~


 
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Crash
Guest
Posts: n/a
 
      01-27-2006
Stephen Worthington wrote:
[snip]
>
> I am not sure if Crash's modem is using K = 1024 or K = 1000 (the
> latter most probably but in any case those are normally the raw ADSL
> speed available, after which you have to take off the ATM and PPP
> protocol overheads to get the available TCP/IP bandwidth. And "bps"
> in this case clearly means "bits per second" - if it was bytes, the
> figures would be larger than standard ADSL can support, even
> theoretically.


Thanks Stephen. I was really after a comparison of '4707 Kbps' compared to my
'2 meg' plan and '250 Kbps' to my '192K plan'. At least those were the numbers
I signed up for on the swift plan that Telecom tell me I am still on.

Judging by the responses the Telecom numbers are in bits and the 4707 Kbps,
being 4.707 Mbps is twice my plan rate. If the ADSL modem speeds reported drop
below the Telecom rated speeds (either direction) then the modem may be limiting
network bandpass. Currently it aint so I am relatively happy. I realise that
the real bandpass available at any given time (either direction) is another
matter entirely and likely to be lower than the plan.

Many thanks for all the responses.

Crash.
 
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