Hi!

I configured the carambola board as WiFi client (station) mode that works fine when traffic is initiated by the caranbola board but when trying to access the carambola board from another PC in the wlan, then the carambola board doesn't response. Here's the exact procedure to reproduce the problem:

1. Configure the wlan, then reboot

a) in "/etc/config/network" add entry

config 'interface' 'wlan'
option 'proto' 'dhcp'

b) in "/etc/config/wireless" mod entry

config 'wifi-iface'
option 'device' 'radio0'
option 'network' 'wlan'
option 'mode' 'sta'
option 'ssid' 'my_wlan_ssid'
option 'encryption' 'psk2'
option 'key' my_wlan_key'

2. Check which ip address the target got (i.e. 192.168.0.109 in my case)

3. Ping the carambola board from another PC in the wlan or try to login via ssh.

A ping will tell "Destination Host Unreachable" and ssh will tell "ssh: connect to host 192.168.0.109 port 22: No route to host".

4. Add an arp entry for the carambola board on the PC:

sudo arp -s 192.168.0.109 00:0e:3b:1e:75:b7

Now it's possible to ping the carambola board or login via ssh.

BTW.: Alternatively, the PC will get a temporary arp entry when pinging the PC from the carambola board, first. Howerver, that arp entry will be lost again after some time of in-activity. Anyway, none of the two variants are a real solution.

Please note that the very problem also shows up when using a RT73USB bases USB WLAN dongle with the carambola board. The problem is even there when using an ARM bases embedded system with the RT73USB. So for sure not only the rt2800pci but at least also the rt73usb is affected and it is not specific to the carambola board. The problem seems to be known since at least 2009 but I couldn't find a cure, yet. I stumbled upon the following one, but that didn't helped:

http://blog.sysbite.org/complete-rt73-r ... linux-arm/

I didn't yet tried out AP mode, but I guess there is no problem - otherwise I would have expected more complaints in this Forum

Additional information: I check with tcpdump that the arp request goes out from the PC, but it never ever reaches the carambola board.

Feedback is highly appreciated!

regards

Bernhard

Just a quick update: in AP mode it works just fine (as expected)! Means: after booting the carambola in AP mode, it is possible to ping/ssh to the board without the need to add an arp entry on the PC or to ping the PC from the carambole, first. I tested it with the on-board wifi (rt2800pci) but I guess rt73usb will behave the same way.

regards

Bernhard

Of course ARP entries will disappear, they're supposed to have a TTL.
This all sounds like a problem with your network setup in general (specifically with your router, if all or most WiFi based devices get left out).

In case there currently is no IP to MAC association for a given machine (which can easily happen because ARP entries are temporary), an ARP request is broadcasted on the network and the machine holding the IP address is supposed to respond, right?. Now the situation is that I can see that the ARP request going out of the PC (using tcpdump), but the carambola doesn't receive the request, hence it doesn't respond. But this only happens so in client (station) mode. When the Carambola board is AP, then the ARP request is received and responded as expected. BTW.: In the mean time, I have read more ARP issue reports and sometimes it appears to help to swap out the AP. I'll try that out.

regards

Bernhard

Bernhard,

Are you still having this ARP problem or did you find a solution?

I am having the exact same issue with different hardware. My access point is a Picostation M2 and my devices are custom linux devices.

Regards,
Steve

Hi!

I didn't looked into it since then, sry.