Introduction for Administrative Users > Ethernet Ports on the OnBoard > Public Ethernet Ports

Public Ethernet Ports
On the public side of the OnBoard, the primary and secondary Ethernet ports are referred to as eth0 and eth1. Optionally-added Ethernet PCMCIA cards are referred to as eth2 and eth3, and if they are present, they are treated as public interfaces.
The secondary Ethernet port on the OnBoard can optionally be configured for failover, which is also referred to as bonding. Failover is important for high-availability environments where constant accessibility is required to support mission-critical applications. Failover automatically redirects traffic from the primary Ethernet port to the secondary Ethernet port if the primary interface fails. The primary Ethernet port continues to be monitored, and when it starts functioning again, traffic is then automatically redirected back through the primary Ethernet port again. All connection sessions continue without interruption.
With failover, both the primary and secondary Ethernet ports are assigned a single IP and single MAC [Ethernet] address.
After failover is enabled, the bonded Ethernet interfaces are referred to as “bond0.”
For example, when failover is set, the ifconfig command lists bond0 along with eth0 and eth1 as shown in the following screen example. Note that the “HWaddress” [MAC address] and “inet addr” [IP address] are identical for bond0, eth0, and eth1.
 
bond0 Link encap:Ethernet HWaddr 00:60:2E:00:4F:97
inet addr:172.20.0.131 Bcast:172.20.255.255 Mask:255.255.0.0
eth0 Link encap:Ethernet HWaddr 00:60:2E:00:4F:97
inet addr:172.20.0.131 Bcast:172.20.255.255 Mask:255.255.0.0
 
...
eth1 Link encap:Ethernet HWaddr 00:60:2E:00:4F:97
inet addr:172.20.0.131 Bcast:172.20.255.255 Mask:255.255.0.0

Introduction for Administrative Users > Ethernet Ports on the OnBoard > Public Ethernet Ports