Specifications

230 Implementing IBM System Networking 10Gb Ethernet Switches
track ports
ACC-1#
5.4.2 Layer 2 Failover
The primary application for Layer 2 Failover is to support Network Adapter Teaming. With
Network Adapter Teaming, all the NICs on each server share an IP address, and are
configured into a team. One NIC is the primary link, and the other is a standby link. For more
details, see the documentation for your Ethernet adapter.
Layer 2 Failover can be enabled on any trunk group in the switch, including LACP trunks.
Trunks can be added to failover trigger groups. Then, if some specified number of monitor
links fail, the switch disables all the control ports in the switch. When the control ports are
disabled, it causes the NIC team on the affected servers to fail over from the primary to the
backup NIC. This process is called a
failover event.
When the appropriate number of links in a monitor group return to service, the switch enables
the control ports. This action causes the NIC team on the affected servers to fail back to the
primary switch (unless Auto-Fallback is disabled on the NIC team). The backup switch
processes traffic until the primary switch’s control links come up, which can take up to
5 seconds.
For more details about the Layer 2 Failover feature, see Chapter 2, “IBM System Networking
Switch 10Gb Ethernet switch features” on page 51.
For our Layer 2 Failover implementation, we used portchannel 1 and portchannel 2 on the
ACC-1 and ACC-2 access switches to control the SRV-1 port on the switch (port 7). For a
reminder of the topology, see the network diagrams in the Chapter 3, “Reference
architectures” on page 107.
Basically, when uplink trunks of ACC-1 or ACC-2 go down, the access switches disable the
server port in order for the NIC teaming mechanism on the server to use the other
network interface.
Not all the options available in IBM Networking OS were used for our Layer 2 Failover
configuration. For detailed information about failover configuration commands, see 5.5, “More
information” on page 238.
Complete the following steps to enable, configure, and verify Layer 2 Failover:
1. Enable Layer 2 Failover.
Run failover enable to enable Layer 2 failover globally (Example 5-80).
Example 5-80 Enable Layer 2 Failover on the switch
ACC-1#configure terminal
Enter configuration commands, one per line. End with Ctrl/Z.
ACC-1(config)#failover enable
ACC-1(config)#^Z
ACC-1#
Link limits: Only two links per server can be used for Layer 2 Failover (one primary and
one backup). Network Adapter Teaming allows only one backup NIC for each
server blade.