How to find out why an IP address is not allocated for the Raspberry Pi connected to the LAN port of the router?

Question

linux

Bought Raspberry Pi 2B . I follow strictly the instructions for installing Arch Linux ARM on a 4 GB memory card, it says that the DHCPCd daemon should be started automatically at boot time. I insert a USB flash drive, connect an ethernet cable and then power. Two indicators light up - red PWR and green ACT, then the indicators on the LAN ports of the router and Raspberry Pi themselves light up and after a while the green ACT indicator goes out.
However, for some reason, the router does not issue an IP address to the device. The router itself runs on OpenWrt, in the LuCI control panel in the "Switch" tab you can see the following:

I.e. the router clearly sees that something is connected to the first port.
Some router logs when connecting to a LAN port:
dmesg:

[71591.750000] eth0: link up (1000Mbps/Full duplex)
[71591.750000] br-lan: port 1(eth0) entered forwarding state
[71591.750000] br-lan: port 1(eth0) entered forwarding state
[71593.750000] br-lan: port 1(eth0) entered forwarding state

syslog:

Thu May  7 12:13:08 2015 daemon.notice netifd: Network device 'eth0' link is up
Thu May  7 12:13:08 2015 kern.info kernel: [71591.750000] eth0: link up (1000Mbps/Full duplex)
Thu May  7 12:13:08 2015 kern.info kernel: [71591.750000] br-lan: port 1(eth0) entered forwarding state
Thu May  7 12:13:08 2015 kern.info kernel: [71591.750000] br-lan: port 1(eth0) entered forwarding state
Thu May  7 12:13:10 2015 kern.info kernel: [71593.750000] br-lan: port 1(eth0) entered forwarding state

Why can't it give out an IP address? How to check what is happening without connecting to a monitor? I checked the cable itself, when the laptop is connected, the IP address is allocated.

Answer 1

UPD :
I'm sorry, when writing the original answer, I did not carefully read the text of the question.

How to check what is happening without connecting to a monitor?

You can connect a laptop to a router (to one of the switched ports) and use a traffic analyzer (wireshark, tcpdump) to see if the Raspberry PI is sending DHCPDISCOVER messages (they are broadcast). If not, then the problem is somewhere on the device itself. If so, you will need to further analyze DHCP traffic and settings of the DHCP server (and, probably, the client).

Answer 2

link up ( 1000Mbps /Full duplex)

Doesn't the raspberry still have a 100Mbps network?

Answer 3

Recently connected Raspberry to the network, there was a similar problem. Plugged the USB power cable into USB3 and it worked. Apparently there was not enough food.