Determining if there are Multiple Network Cards on a AIX Machine

Problem(Abstract)

How to determine the number of network cards on a AIX machine.

Resolving the problem

INTRODUCTION

You may need to find the IP address or addresses for your AIX system, but may not know whether the system contains more than one Network Interface Card (NIC).


METHOD

On AIX systems, the command ifconfig supports an option (-a) to list all of the interfaces on the machine. The output of ifconfig -a varies among operating systems, but should include the IP address of any Network Interface Card (NIC) on the machine.

The interface name will be a 3 to 4 character indicator like hme0, en0 or lc1. Each entry will always begin with the interface name and a colon. This will usually be followed by a set of flags. The flag LOOPBACK indicates that the interface is the local loop back interface and not an actual NIC. Somewhere in the entry for an NIC there is a keyword of inet followed by an IP address. This is the IP address of the interface.

Execute ifconfig -a and look for entries with IP addresses that are not 127.0.0.1. The IP addresses are preceded by inet. 

Note: Some systems that support IP version 6 (IPv6) will have two interfaces for each NIC, one for IPv6 and the other for IP version 4 (IPv4). The IPv6 interface will not have an inet parameter, instead it will have an inet6 parameter that will not look like an IP address. Instead of decimal numbers separated by periods an IPv6 address is made up of hexadecimal numbers separated by colons.


Examples:

Output from an AIX machine: 

The output shows that interface en0 is an actual NIC that has an internet (IP) address of 10.25.16.1 (IP addresses have been changed as a security precaution). The device lo0 is a local loop back as shown by the LOOPBACK flag and the internet address of 127.0.0.1

$ ifconfig -a
en0: flags=4e080863< UP,BROADCAST,NOTRAILERS,RUNNING,
SIMPLEX,MULTICAST,GROUPRT,64BIT,PSEG>
     inet 10.25.16.1 netmask 0xffffff00 broadcast 109.25.146.145
lo0: flags=e08084b < UP,BROADCAST,LOOPBACK,RUNNING,SIMPLEX,
MULTICAST,GROUPRT,64BIT>
     inet 127.0.0.1 netmask 0xff000000 broadcast 127.255.255.255
     inet6 ::1/0


Finding ifconfig

The ifconfig command may not be in your default PATH. Look in the following directories:

• /usr/bin
• /etc
• /usr/etc
• /sbin
• /usr/sbin

You can still use it by simply including the full path to the ifconfig file on the command line. If you cannot find ifconfig, check the man page for ifconfig or use the find command.

For more information, check with your system administrator or the operating system documentation.

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