Common TCP/IP problems with network interfaces

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Network interfaces are configured automatically during the first system startup after the adapter card is installed. However, there are certain values that must be set in order for TCP/IP to start. These include the host name and Internet address and can be set using the SMIT fast path, smit mktcpip.

If you choose the SMIT method, use the smit mktcpip fast path to set these values permanently in the configuration database. Use the smit chinet and smit hostname fast paths to change them in a running system. The smit mktcpip fast path minimally configures TCP/IP. To add adapters, use the Further Configuration menu, which can be reached with the smit tcpip fast path.

If you have already checked these to verify accuracy and you are still having trouble sending and receiving information, check the following:

  • Verify that your network adapter has a network interface by executing the netstat -i command. The output should list an interface, such as tr0, in the Name column. If it does not, create a network interface by entering the SMIT fast path smit mkinet.
  • Verify that IP address for the interface is correct by executing the netstat -i command. The output should list the IP address in the Network column. If it is incorrect, set the IP address by entering the SMIT fast path smit chinet.
  • Use the arp command to make sure you have the complete IP address for the target machine. For example: 
    arp -a

    The arp command looks for the physical adapter address. This command might show an incomplete address. For example:

    ? (192.100.61.210) at (incomplete)

    This could be due to an unplugged machine, a stray address with no machine at that particular address, or a hardware problem (such as a machine that connects and receives packets but is not able to send packets back).

  • Look for errors on the adapter card. For example: 
    netstat -v

    The netstat -v command shows statistics for the Ethernet, Token Ring, X.25, and 802.3 adapter device drivers. The command also shows network and error logging data for all device drivers active on an interface including: No Mbufs Errors, No Mbuf Extension Errors, and Packets Transmitted and Adapter Errors Detected.

  • Check the error log by running the errpt command to ensure that there are no adapter problems.
  • Verify that the adapter card is good by running diagnostics. Use the smit diag fast path, or the diag command.