Centos 5.0 默认不支持8101e的网卡驱动去官方下个驱动

<Linux device driver for Realtek Ethernet controllers>

This is the Linux device driver released for RealTek RTL8101E and RTL8102E(L), the Fast Ethernet controller with PCI-Express interface.

<Requirements>

- kernel source tree (supported Linux kernel 2.6.x and 2.4.x)
- For linux kernel 2.4.x, this driver supports linux kernel 2.4.20 and latter.
- compiler/binutils for kernel compilation

<Quick install with proper kernel settings>
Check whether the built-in driver, r8169.ko (or r8169.o for kernel 2.4.x), is installed.
   # lsmod | grep r8169

If it is installed, please remove it.
   # rmmod r8169
note: If the built-in driver cannot removed by rmmod, please edit /etc/modprobe.conf and comment 'alias eth0 r8169'. Then, remmove it again or reboot your computer.

Unpack the tarball :
   # tar vjxf r8101-8.aaa.bb.tar.bz2

Change to the directory:
   # cd r8101-8.aaa.bb

If you are running the target kernel, then you should be able to do :

   # make clean modules (as root or with sudo)
   # make install
   # depmod -a
   # insmod ./src/r8101.ko (or r8101.o for kernel 2.4.x)

You can check whether the driver is loaded by using following commands.

   # lsmod | grep r8101
   # ifconfig -a

If there is a device name, ethX, shown on the monitor, the linux
driver is loaded. Then, you can use the following command to activate
the ethX.

   # ifconfig ethX

   ,where X=0,1,2,...

<Set the network related information>
1. Set manually
   a. Set the IP address of your machine.

    # ifconfig ethX "the IP address of your machine"

   b. Set the IP address of DNS.

     Insert the following configuration in /etc/resolv.conf.
  
    nameserver "the IP address of DNS"

   c. Set the IP address of gateway.

    # route add default gw "the IP address of gateway"

2. Set by doing configurations in /etc/sysconfig/network-scripts
    /ifcfg-ethX for Redhat and Fedora, or /etc/sysconfig/network
    /ifcfg-ethX for SuSE. There are two examples to set network
    configurations.

   a. Fixed IP address:
    DEVICE=eth0
    BOOTPROTO=static
    ONBOOT=yes
    TYPE=ethernet
    NETMASK=255.255.255.0
    IPADDR=192.168.1.1
    GATEWAY=192.168.1.254
    BROADCAST=192.168.1.255

   b. DHCP:
    DEVICE=eth0
    BOOTPROTO=dhcp
    ONBOOT=yes

<Modify the MAC address>
There are two ways to modify the MAC address of the NIC.
1. Use ifconfig:

   # ifconfig ethX hw ether YY:YY:YY:YY:YY:YY

    ,where X is the device number assigned by Linux kernel, and
    YY:YY:YY:YY:YY:YY is the MAC address assigned by the user.

2. Use ip:

   # ip link set ethX address YY:YY:YY:YY:YY:YY

    ,where X is the device number assigned by Linux kernel, and
    YY:YY:YY:YY:YY:YY is the MAC address assigned by the user.

<Force Link Status>

1. Force the link status when insert the driver.

    If the user is in the path ~/r8101, the link status can be forced
    to one of the 4 modes as following command.

   # insmod ./src/r8101.ko speed=SPEED_MODE duplex=DUPLEX_MODE autoneg=NWAY_OPTION

   ,where
    SPEED_MODE = 100 for 100Mbps
      = 10 for 10Mbps
    DUPLEX_MODE = 0 for half-duplex
      = 1 for full-duplex
    NWAY_OPTION = 0 for auto-negotiation off (true force)
      = 1 for auto-negotiation on (nway force)
   For example:

    # insmod ./src/r8101.ko speed=100 duplex=0 autoneg=1

   will force PHY to operate in 100Mpbs Half-duplex(nway force).

2. Force the link status by using ethtool.
   a. Insert the driver first.
   b. Make sure that ethtool exists in /sbin.
   c. Force the link status as the following command.

    # ethtool -s ethX speed SPEED_MODE duplex DUPLEX_MODE autoneg NWAY_OPTION

    ,where
     SPEED_MODE = 100 for 100Mbps
       = 10 for 10Mbps
     DUPLEX_MODE = half for half-duplex
       = full for full-duplex
     NWAY_OPTION = off for auto-negotiation off (true force)
       = on for auto-negotiation on (nway force)

   For example:
  
    # ethtool -s eth0 speed 100 duplex full autoneg on

   will force PHY to operate in 100Mpbs Full-duplex(nway force).