System from scratch - network problem

Hello,

As an exercise I'm trying to build a linux system for the beagle board
xM Rev C from scratch. I'm using the 2.6.35 kernel sources and
BusyBox 1.19.3. I started out with the "omap3_beagle_defconfig" kernel
configuration and made the following changes:

CONFIG_USB_USBNET=y
CONFIG_USB_NET_AX8817X=y
CONFIG_USB_NET_CDCETHER=y
...
CONFIG_USB_ETH=y

I compiled the kernel and busybox and put them on a micro SD card and
installed the modules. Then I added "/etc/fstab" to mount the proc and
sys filesystems. The system boots fine and I get a command prompt.
When booted I do the following to enable the usb0 device:

/ # mount proc
/ # mount sys
/ # ifconfig lo 127.0.0.1 netmask 255.0.0.0 up
/ # ifconfig usb0 10.0.0.250 netmask 255.255.255.0 up

Then I can ping 127.0.0.1 and 10.0.0.250 just fine but when I try to
ping the host pc I get nothing (I checked the cables and that isn't
the problem):

/ # ping -c 10 10.0.0.117
PING 10.0.0.117 (10.0.0.117): 56 data bytes

--- 10.0.0.117 ping statistics ---
10 packets transmitted, 0 packets received, 100% packet loss

Also the leds on the ethernet port of the board don't light up so I
guess the port isn't getting any power. Am I missing some kernel
configuration option or do I need to do something else to startup the
ethernet port?