On two occassions in the last week, i encountered situation where the NIC (network interface card) card was not functional from Linux side.
Linux has excellent support for 10/100 and 100/1000 ethernet PCI NIC cards, even the ones that require a binary firmware.

In both cases a dual boot system was setup - one was WinXP/Gentoo Linux (Broadcom NIC) and other was WinXP/OpenSuSe Linux 11 (Realtek NIC). This was particulary annoying as i have Realtek NIC cards on all my Intel boxes and nvidia nForce chipset on my AMD64 X2, Asus M2N MX SE board (The forcedeth driver for the ethernet part of nvidia’s nForce chipset is integrated into the kernel and works pretty well). Dual boot setups are quite common today.

The hardware was detected (dmesg and lspci -v). The kernel modules  list (/sbin/lsmod) entry shows the driver.

Module                  Size  Used by
cdc_acm                17600  0
pcspkr                  6656  0
8139too                27176  0
8139cp                 23824  0
bcm43xx               432704  0
serio_raw               9476  0
ieee80211softmac       34248  1 bcm43xx
ieee80211              48372  2 bcm43xx,ieee80211softmac
ieee80211_crypt         8704  1 ieee80211
...

This behaviour seemed strange and so digged a little deeper. Here are some observations and suggestions for anybody facing a similar situation.

On the Windows XP side, go to My Network Places --> Properties --> Select the LAN connection -> Properties --> Configure and then select the Power management tab sheet. Here is what you would see.

Please UNCHECK the option shown above as it causes Windows to turn off the device to save power and later the device does not come up on the Linux side.

The other two things you need to take care of are in the BIOS settings:

• Enable the 'Wake on LAN' (WoL) option.
• Enable the PXE boot option for your NIC card (if it supports).

Having made the requisite changes, please power down the system. Disconnect the UTP cable and the power cable. I'd suggest having a delay of some 15 seconds (to discharge the capacitors). Re-connect the Power cable and then the UTP cable.

Now, power on your system and select Gentoo or OpenSuSe Linux from the GRUB menu. You're Linux system will in most cases have a functional network card. Depending on your configuration eg. static IP or DHCP assigned IP address, you may like to run some traffic using the 'ping' command to verify this.

Hope this posting of mine helps the community members solve their connectivity issues and also educate the tech support guys of Beam cable / Sify that Realtek cards are detected and work well with Linux.