Centos NIC status detection

Because the ifconfig command cannot view the NIC status, there are five ways to check the NIC status and whether the NIC is connected to HowtocheckphysicalNetworkLinkStatusonLinux (RHEL/Centos: http://linuxsupporttips.wordpress.com/2011/08/01/how-to-check-physical-network-l because the ifconfig command can not see some of the NIC status, the following five ways to view the NIC status, whether to connect to the network

How to check physical Network Link Status on Linux (RHEL/Centos)
Original article: http://linuxsupporttips.wordpress.com/2011/08/01/how-to-check-physical-network-link-status-on-linux-rhelcentos/

There are several ways to check Link status on RHEL,
As far I used to check by 5-ways. Refer Below

1)
# Dmesg | grep eth
.....
E1000: eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: None
E1000: eth1 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: None
 
2)
# Mii-tool
Eth0: negotiated 100baseTx-FD, link OK
Eth1: negotiated 100baseTx-FD, link OK

3)
# Ethtool eth0 | grep Link
Link detected: yes

4)
# Cat/sys/class/net/eth0/operstate
Up

5)
# Ip link show
2: eth0: mtu 1500 qdisc pfifo_fast qlen 1000 link/ether 00: 0c: 29: b0: ef: e4 brd ff: ff
3: eth1: mtu 1500 qdisc pfifo_fast qlen 1000 link/ether 00: 0c: 29: b0: ef: ee brd ff: ff