mukhtar
Posts: 21
Joined: Tue Sep 13, 2011 11:21 pm

Re: Model B : IO speed , usb and ethernet share the same bandwidth?

Tue Nov 29, 2011 5:18 am

Howdy folks,

I still dont understand how this works..something about the usb and the ethernet using the same bandwidth or so? I tried the wiki, no help. Any clarification will be appreciated:

ALSO: Its practically december! WHEN can I get me some RPI??

attiatte
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Joined: Sat Nov 12, 2011 6:07 pm
Contact: Website

Re: Model B : IO speed , usb and ethernet share the same bandwidth?

Tue Nov 29, 2011 5:25 am

I also would like to hear more about this. Has anyone benchmarked this (USB <-> ethernet)? I\'d like to think that one person with an alpha board also wondered the same thing. :)

Wooloomooloo
Posts: 92
Joined: Fri Nov 25, 2011 10:52 am

Re: Model B : IO speed , usb and ethernet share the same bandwidth?

Tue Nov 29, 2011 7:56 am

Well, it IS exactly one click away from the wiki page (yes, the first link). Anyway, what the CPU/SoC has is a single hi-speed USB port - that\'s what you see on the model A. What the model B does is add the Ethernet chip, which actually takes that one USB port, splits it up with its internal USB hub giving you another two USB ports instead, and tacks on the Ethernet part itself as a third branch of the same hub.

So yes, the two USB ports and the Ethernet port are actually all sharing the bandwidth of the original SoC USB port they\'re all connected to...

na1pir
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Re: Model B : IO speed , usb and ethernet share the same bandwidth?

Tue Nov 29, 2011 8:08 am

If you still don\'t understand, this USB hub (http://www.dealextreme.com/p/usb-2-0-3- ... able-51436) with Ethernet works similar. It takes 1 USB and outputs 3 USB ports and one Ethernet port. But they all share same bandwidth.

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Montekuri
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Re: Model B : IO speed , usb and ethernet share the same bandwidth?

Tue Nov 29, 2011 9:13 am

[quote]Quote from mukhtar on November 29, 2011, 05:18
ALSO: Its practically december! WHEN can I get me some RPI??[/quote]

When they finish the tests with the beta boards.

mukhtar
Posts: 21
Joined: Tue Sep 13, 2011 11:21 pm

Re: Model B : IO speed , usb and ethernet share the same bandwidth?

Tue Nov 29, 2011 12:13 pm

so speedwise its going to be terrible if you got all ports in use + ethernet for internet?

tek-monkey
Posts: 24
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Re: Model B : IO speed , usb and ethernet share the same bandwidth?

Tue Nov 29, 2011 12:22 pm

No worse than my iomega NAS/media player I\'ll wager, that does 1.6 meg on a 100 LAN connection!

jamesh
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Re: Model B : IO speed , usb and ethernet share the same bandwidth?

Tue Nov 29, 2011 12:24 pm

[quote]Quote from mukhtar on November 29, 2011, 12:13
so speedwise its going to be terrible if you got all ports in use + ethernet for internet?[/quote]

Depends on what you have attached. Keyboard and mouse take very little bandwidth, it\'s attached HD\'s that soaks up the most, followed by network traffic. Even with an HD attached, plus ethernet @ normal ADSL speeds, it should be plenty quick enough.
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kme
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Re: Model B : IO speed , usb and ethernet share the same bandwidth?

Tue Nov 29, 2011 12:40 pm

[quote]Quote from tek-monkey on November 29, 2011, 12:22
No worse than my iomega NAS/media player I\'ll wager, that does 1.6 meg on a 100 LAN connection![/quote]Except that USB2 is half duplex, so you can\'t simultaneously listen to the LAN port and write to a USB disk. It\'s like walkie-talkies: one speak - the other end listen. Unlike mobile phones where you can speak and listen at the same time (full duplex).

smoffen
Posts: 2
Joined: Sun Nov 06, 2011 10:43 pm

Re: Model B : IO speed , usb and ethernet share the same bandwidth?

Tue Nov 29, 2011 12:43 pm

The topic has been partially covered in

http://www.raspberrypi.org/forum?mingle ... opic&t=984

Quote from how to easily determine perfomance below. However, we are probably pretty close to being able to test this on the shipping units.

[quote]A simple test of performance could be done quite easily. Just enable the FTP server on the r-pi, hook up an external USB drive, then upload a suitably large file to the drive and download it again while noting the transfer speeds in both directions. As FTP transfers are just pushing data over a regular TCP connection (without encryption) it would give a pretty good indication of what kind of performance to expect when pushing data in both directions through the SoC USB port using the separate USB + ethernet chip.

Any of you alpha board owners willing to spare a few minutes to help settle this matter?[/quote]

Wooloomooloo
Posts: 92
Joined: Fri Nov 25, 2011 10:52 am

Re: Model B : IO speed , usb and ethernet share the same bandwidth?

Tue Nov 29, 2011 4:47 pm

[quote]Quote from smoffen on November 29, 2011, 12:43
The topic has been partially covered in

http://www.raspberrypi.org/forum?mingle ... opic&t=984

Quote from how to easily determine perfomance below. However, we are probably pretty close to being able to test this on the shipping units.

[quote]A simple test of performance could be done quite easily. Just enable the FTP server on the r-pi, hook up an external USB drive, then upload a suitably large file to the drive and download it again while noting the transfer speeds in both directions. As FTP transfers are just pushing data over a regular TCP connection (without encryption) it would give a pretty good indication of what kind of performance to expect when pushing data in both directions through the SoC USB port using the separate USB + ethernet chip.

Any of you alpha board owners willing to spare a few minutes to help settle this matter?[/quote]
[/quote]
Interesting. I\'m quite curious about such a test too. One application I can think of that would rather push the envelope here would be an analog TV tuner dongle, streaming TV on demand right back via Ethernet on the LAN. I think the data volume of raw grabbed frames going both ways would be... significant.

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