RPi Model B RJ45 network socket speed?


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by raspberrypilover » Thu Jun 13, 2013 1:35 pm
Definitively could someone state what the actual speed of the RJ45 network socket is on the RPi Model B?

Is it the usual 100MB/second or is it reduced substantially to reflect the modest processing abilities of the RPi?

I am very much a novice in this area, so any technical elaboration or suggestions for follow-up enquiry are very welcome.

Ta. x
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by rpdom » Thu Jun 13, 2013 1:44 pm
The actual connection speed will be either 100Mbit/s or 10Mbit/s depending on what you connect it to. Normally it will be 100Mbits/s.

The Pi's Ethernet is connected to the system via the USB. Theoretically that can support the full 100Mb too, as it has a maximum transfer rate of 480Mb/s, however there are overheads on USB and it depends what else is connected via USB.

Also, the CPU on the Pi is not a very powerful one and it will struggle to try and maintain a continuous 100Mb/s. It might manage it in short bursts.
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by raspberrypilover » Thu Jun 13, 2013 2:21 pm
rpdom wrote:The actual connection speed will be either 100Mbit/s or 10Mbit/s depending on what you connect it to. Normally it will be 100Mbits/s.

The Pi's Ethernet is connected to the system via the USB. Theoretically that can support the full 100Mb too, as it has a maximum transfer rate of 480Mb/s, however there are overheads on USB and it depends what else is connected via USB.

Also, the CPU on the Pi is not a very powerful one and it will struggle to try and maintain a continuous 100Mb/s. It might manage it in short bursts.


Thanks so much for replying. So, the RPi's USB socket must therefore be USB 2.0?
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by RaTTuS » Thu Jun 13, 2013 2:26 pm
100Mbps network card [fast ethernet]
is bits/second
a byte is 8 bits
100 / 8 = 12.5MBps [less because of overhead]
the NIC chip on the RPI provides a 2nd USB port and the NIC
usb2 high speed is 480Mbps

you are realistly going to get approx 5MB/s [as measured by scp] to or from your RPI
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by raspberrypilover » Thu Jun 13, 2013 2:45 pm
RaTTuS wrote:100Mbps network card [fast ethernet]
is bits/second
a byte is 8 bits
100 / 8 = 12.5MBps [less because of overhead]
the NIC chip on the RPI provides a 2nd USB port and the NIC
usb2 high speed is 480Mbps

you are realistly going to get approx 5MB/s [as measured by scp] to or from your RPI


Thanks for your reply.

OK - to be clear - the reason I am asking this question is because I am interested in setting up a RPi to be used as a VPN server. So I need to expect to get a decent speed when connecting to a device using the VPN. To my untutored mind the projected speed of the NIC is what will ultimately determine the connection speed of a VPN connection (perhaps RPi processor limitations come into this, too). So, from what you say I might only expect a 5MB/s throughput speed if using the RPi as a VPN server? With fibre broadband that will be disappointing if I use the VPN connection for streaming video, for example.

Also, on the Model B is it possible to know if the upper or lower USB socket is native, or provided by the NIC? If I were to know which is which, would I affect the NIC speed when using USB simultaneously should I intentionally use the native USB port (i.e. the one NOT provided by the NIC)?
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by rpdom » Thu Jun 13, 2013 3:00 pm
raspberrypilover wrote:So, from what you say I might only expect a 5MB/s throughput speed if using the RPi as a VPN server? With fibre broadband that will be disappointing if I use the VPN connection for streaming video, for example.


5MBytes/second isn't too bad, plenty enough for most streaming video.

Also, on the Model B is it possible to know if the upper or lower USB socket is native, or provided by the NIC? If I were to know which is which, would I affect the NIC speed when using USB simultaneously should I intentionally use the native USB port (i.e. the one NOT provided by the NIC)?


Both USB sockets on the model B are provided by the LAN chip. The native USB goes from the SoC to the LAN chip, then the LAN chip provides Ethernet and a USB hub that feeds both USB sockets.

The model A is the only Pi with direct, native USB connection to its single socket.
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by jamesh » Thu Jun 13, 2013 3:11 pm
raspberrypilover wrote:
RaTTuS wrote:100Mbps network card [fast ethernet]
is bits/second
a byte is 8 bits
100 / 8 = 12.5MBps [less because of overhead]
the NIC chip on the RPI provides a 2nd USB port and the NIC
usb2 high speed is 480Mbps

you are realistly going to get approx 5MB/s [as measured by scp] to or from your RPI


Thanks for your reply.

OK - to be clear - the reason I am asking this question is because I am interested in setting up a RPi to be used as a VPN server. So I need to expect to get a decent speed when connecting to a device using the VPN. To my untutored mind the projected speed of the NIC is what will ultimately determine the connection speed of a VPN connection (perhaps RPi processor limitations come into this, too). So, from what you say I might only expect a 5MB/s throughput speed if using the RPi as a VPN server? With fibre broadband that will be disappointing if I use the VPN connection for streaming video, for example.

Also, on the Model B is it possible to know if the upper or lower USB socket is native, or provided by the NIC? If I were to know which is which, would I affect the NIC speed when using USB simultaneously should I intentionally use the native USB port (i.e. the one NOT provided by the NIC)?


What speed is your fibre broadband - would have to be pretty good to be faster than the Raspi ethernet port at 5MB/s.
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by raspberrypilover » Thu Jun 13, 2013 3:18 pm
jamesh wrote:
raspberrypilover wrote:
RaTTuS wrote:100Mbps network card [fast ethernet]
is bits/second
a byte is 8 bits
100 / 8 = 12.5MBps [less because of overhead]
the NIC chip on the RPI provides a 2nd USB port and the NIC
usb2 high speed is 480Mbps

you are realistly going to get approx 5MB/s [as measured by scp] to or from your RPI


Thanks for your reply.

OK - to be clear - the reason I am asking this question is because I am interested in setting up a RPi to be used as a VPN server. So I need to expect to get a decent speed when connecting to a device using the VPN. To my untutored mind the projected speed of the NIC is what will ultimately determine the connection speed of a VPN connection (perhaps RPi processor limitations come into this, too). So, from what you say I might only expect a 5MB/s throughput speed if using the RPi as a VPN server? With fibre broadband that will be disappointing if I use the VPN connection for streaming video, for example.

Also, on the Model B is it possible to know if the upper or lower USB socket is native, or provided by the NIC? If I were to know which is which, would I affect the NIC speed when using USB simultaneously should I intentionally use the native USB port (i.e. the one NOT provided by the NIC)?


What speed is your fibre broadband - would have to be pretty good to be faster than the Raspi ethernet port at 5MB/s.



Usually I get between 45Mb/s and 55Mb/s download, and 5Mb/s to 10Mb/s upload. I wanted to use the VPN within the house also, so good speeds between wi-fi base station and appliances were my desired intention.
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by RaTTuS » Thu Jun 13, 2013 3:22 pm
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by raspberrypilover » Thu Jun 13, 2013 3:33 pm
RaTTuS wrote:http://en.wikipedia.org/wiki/Data_rate_units
so you are on cable then ?
Image


Wow! I envy your bi-directional symmetric speeds! Is that a work or domestic connection? If it's domestic how much do you pay a month?
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by RaTTuS » Thu Jun 13, 2013 3:38 pm
no that is work - and you don't want to know ....
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by rpdom » Thu Jun 13, 2013 4:16 pm
I currently only get about 29.6Mbs up and 1.9Mbs down, since I'm on the slowest option I can get through VirginMedia.

I have been getting odd results from some speedtest sites. The uswitch one did report my connection as 85Mbs down and 9Mbs up for a while, but has now decided that I get 49Mbs down and 2.5Mbs up.

I'd probably get a slightly higher reading if I wasn't going through three network switches to get to my cable modem.
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by drgeoff » Thu Jun 13, 2013 4:23 pm
rpdom wrote:I currently only get about 29.6Mbs up and 1.9Mbs down, ....


If that is true it is very unusual. :lol:
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by rpdom » Thu Jun 13, 2013 4:43 pm
drgeoff wrote:
rpdom wrote:I currently only get about 29.6Mbs up and 1.9Mbs down, ....


If that is true it is very unusual. :lol:


Um, yes. Swap "up" and "down" there. Sorry :lol:

When I first got this connection I was getting 512Kbs down, which was a bit more than the fat pipe at work that was shared between 40 odd users. I once used that (via VPN) to back up a work server from home when its tape drive was out of action and it was quite a bit faster than backing up to the tape drive (DDS1 was very slow!)
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