Missing carrier on ethernet.

[deva]

Hi

I have aqcuired 3 Olimex A10S-OLinuXine-MICRO boards and set them up as a buildserver for a armv7 board I am developing.
When first set up everything seemed to be workind, but at some point the ethernet stopped detecting the carrier signal.
This results in the dhcp client to never correctly gain an ip address, and basically renders my buildserver useless.
I have tested with the supplied debian image with the same results:
A10S_debian_3_4_GPIO_LAN_USBs_SDs_HDMI_LCD_I2C_100KHz_TS_4G_release_4 from https://www.olimex.com/wiki/A10s-OLinuXino-MICRO#Linux

Here is the output from "/etc/init.d/networking start":
root@A10s:~# /etc/init.d/networking start
[....] Configuring network interfaces...Internet Systems Consortium DHCP Client 4.2.2
Copyright 2004-2011 Internet Systems Consortium.
All rights reserved.
For info, please visit https://www.isc.org/software/dhcp/

<6>sunxi_emac sunxi_emac.0: eth0: link down
[  834.423341] sunxi_emac sunxi_emac.0: eth0: link down
Listening on LPF/eth0/02:93:08:c0:b2:26
Sending on   LPF/eth0/02:93:08:c0:b2:26
Sending on   Socket/fallback
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 5
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 8
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 20
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 7
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 10
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 11
No DHCPOFFERS received.
No working leases in persistent database - sleeping.
done.


Here is the output of my own dhcpcd execution (with gentoo image):
root@gentoo-A10s:~# dhcpcd eth0
dhcpcd[1015]: version 6.2.0 starting
dhcpcd[1015]: all: IPv6 kernel autoconf disabled
dhcpcd[1015]: eth0: IPv6 kernel autoconf disabled
dhcpcd[1015]: eth0: waiting for carrier
dhcpcd[1015]: timed out
dhcpcd[1015]: allowing 8 seconds for IPv4LL timeout
dhcpcd[1015]: timed out
dhcpcd[1015]: exited

Ane hints to a solution would be more than welcome.

Kind regards
Bent Bisballe Nyeng

[deva]

It appears that the reason for the missing carrier was that my switch made a shutdown on the port due to some (currently unknown) problem with the connected interface.
I have set up logging on the ports and will report back here if I find anything of interrest.
According to the switch spec, the violation could be anything from "violates the TCP/IP standart" to "signal voltage too high"...