Raspberry Pi Ethernet Problem

Assume you've probably got things to work by now...

I think I just ran into a similar problem in getting my networking to go as well.

Note: I had the additional complication of MAC filtering turned on in my router so I needed to get that all set up first on the router. As well I have DHCP, but with assigned addresses also taken care of on the router (although it should provide any freely available one, I like having the same machine on the same address).

So after doing all that I expected things to start right up as any other device I've ever connected to my router.

What finally got things working was bringing the eth0 interface down and up using the following commands;

ifdown eth0

ifup eth0

Then do the ifconfig and you should see IP addresses assigned to the PI

Final note: I had tried rebooting the Pi and restarting the interface none of which worked for me, but you can try the command to restart the network interface services as follows;

/etc/init.d/networking restart

Sorry but i haven't fixed the issue yet. I was just out of town for the weekend. I did try a different computer on the same jack which worked fine for the internet. I tried putting a new image of wheezy on it but still no solution. I can try to post my windows configuration from ipconfig later today when i get a chance along with trying the ipdown.

I just got my Raspeberry Pi unit today and started looking for a solution to this problem myself. After spending some time looking for the answer I decided to try another cable; even though the first cable was used to connect one of my computers to the internet. Strangely enough it worked just fine when I switched to another cable.

I can't say what causes this behaviour, but it seems like even though the cable works on my laptop it may not work on the Raspberry Pi. Switching to another cable could be helpful despite the cable seems to be working fine. (The LED's on the Pi was on and flickering so I thought everything was OK.)

I guess the Raspberry Pi might be more strict about the cable than my laptop. If anyone have an answer to why this happens I would like to know.

Erik Hepso wrote:

 

I just got my Raspeberry Pi unit today and started looking for a solution to this problem myself. After spending some time looking for the answer I decided to try another cable; even though the first cable was used to connect one of my computers to the internet. Strangely enough it worked just fine when I switched to another cable.

I can't say what causes this behaviour, but it seems like even though the cable works on my laptop it may not work on the Raspberry Pi. Switching to another cable could be helpful despite the cable seems to be working fine. (The LED's on the Pi was on and flickering so I thought everything was OK.)

 

I guess the Raspberry Pi might be more strict about the cable than my laptop. If anyone have an answer to why this happens I would like to know.

Here's my experience: 10/100baseT Ethernet uses twisted differential pairs for RX and TX.  If one side of a pair breaks, some signal still gets through, but with poor signal quality.  Depending on the receiver and cable length, you may be able to get enough frames  through to operate.  Some PHY chips do a better job than others with poor signals.  TCP and other protocols re-transmit if packets don't get through, so as long as some packets get through you still get a connection, though it can be very slow.

John Beetem wrote:

 

Here's my experience: 10/100baseT Ethernet uses twisted differential pairs for RX and TX.  If one side of a pair breaks, some signal still gets through, but with poor signal quality.  Depending on the receiver and cable length, you may be able to get enough frames  through to operate.  Some PHY chips do a better job than others with poor signals.  TCP and other protocols re-transmit if packets don't get through, so as long as some packets get through you still get a connection, though it can be very slow.

Thanks for the answer John.

That sounds plausible. I always thought it was either working or not.

I better check my cables, and perhaps start treating them nicer too.

I inspected the board this weekend and found that resistor 50 is missing!  Could this be why it won't connect?  Also if this is the case does the RMA cover a situation like this? or could I repair it if I can solder that tiny?

According to the RasPi schematics, R50 connects the SD card DAT1 signal.  This should only affect SD card behavior, and then only if the SD card is using a 4-bit data bus.  If your RasPi is booting, then either your SD card doesn't use 4-bit mode or RasPi's software has detected errors using 4-bit mode and has fallen back to 1-bit mode.

You can replace R50 if you have a soldering iron with a small tip and a good pair of tweezers.  However, board modifications generally void the warranty -- I don't know about if doing your own repairs counts as a "modification".  The absence of R50 does suggest that your board slipped through quality control, so who knows what else might be wrong with it?  From what I read, RasPi boards don't go through a lot of Q/C but suppliers tend to be good about replacing defective units.

Just as a follow up for anyone who reads this thread in the future and for all of you helpers...

I had ordered another raspberry pi and just reimaged the sd card, booted up in that one, and the internet worked fine.  I took the sd card out and put it in the old raspberry pi and hooked up the same exact cables and ethernet cord but it still didn't work. With that and the missing resistor I am definitely going to RMA it.  Thank you all for your help!

Hi,

I had the same problem. I was trying to connect to the internet for the first time. I did the same things. Set static address, restarted the pi. Finally the 'ifdown' and 'ifup' did the trick. I had to use "sudo ifdown eth0". Without the sudo I got a permission error.

Thanks you all for the help.

I also am having problems with a Raspberry Pi (a B+). Did have a connection with a wifi adaptor but that broke and will be going back. Tried plugging in an ethernet cable and the hub appears to be seeing the Pi but the Pi says that there is no internet connection. Tried 'sudo ifdown eth0' followed by 'sudo ifup eth0' and got a series of DHCPDISCOVER messages followed by 'No DHCPOFFERS received'. ifconfig shows no internet address against eth0.

Any help would be really appreciated.