To show the Link Status on an interface (Speed, Duplex, MDIX etc) we can use the ethtool command.

From the command line enter:

  /sbin/ethtool ethx (where x is the interface number)

Example:

  /sbin/ethtool eth4    (in this example, eth4 is connected to a Cisco 3560G switch)
  
  
  Settings for eth4:
      Supported ports: [ TP ]
      Supported link modes:   10baseT/Half 10baseT/Full
                              100baseT/Half 100baseT/Full
                              1000baseT/Full
      Supported pause frame use: Symmetric
      Supports auto-negotiation: Yes
      Advertised link modes:  10baseT/Half 10baseT/Full
                              100baseT/Half 100baseT/Full
                              1000baseT/Full
      Advertised pause frame use: Symmetric
      Advertised auto-negotiation: Yes
      Speed: 1000Mb/s
      Duplex: Full
      Port: Twisted Pair
      PHYAD: 1
      Transceiver: internal
      Auto-negotiation: on
      MDI-X: off (auto)
      Supports Wake-on: d
      Wake-on: d
      Current message level: 0x00000007 (7)
                             drv probe link
      Link detected: yes

Example 2

  
  /sbin/ethtool eth0    (in this example, eth is connected to a P ProCurve)
  
  
  Settings for eth0:
      Supported ports: [ TP ]
      Supported link modes:   10baseT/Half 10baseT/Full
                              100baseT/Half 100baseT/Full
                              1000baseT/Full
      Supported pause frame use: Symmetric
      Supports auto-negotiation: Yes
      Advertised link modes:  10baseT/Half 10baseT/Full
                              100baseT/Half 100baseT/Full
                              1000baseT/Full
      Advertised pause frame use: Symmetric
      Advertised auto-negotiation: Yes
      Speed: 100Mb/s
      Duplex: Full
      Port: Twisted Pair
      PHYAD: 1
      Transceiver: internal
      Auto-negotiation: on
      MDI-X: on (auto)
      Supports Wake-on: pumbg
      Wake-on: g
      Current message level: 0x00000007 (7)
                             drv probe link
      Link detected: yes