Use link aggregation instead of VIPA on IBM i

In the past, the only option to provide redundant Ethernet on dedicated network adapters for IBM i was a VIRTUALIP ‘interface’. Starting with IBM i 7.1 TR3, there is a new feature called Link aggregation. It is much better and much easier for implementation than VIPA.

VIPA configuration requires 2 physical  interface, and 3 public IPs. The traffic is routed only thru one interface, while the second is a backup only. Moreover, the configuration process is kind of complicated.

The other option is provision TCP traffic thru VIOS (SEA) to an IBM i host. For someone who has VIOS skills it is easy, but for IBM i stuff, it is usually ‘mission impossible’. Also the SEA brings additional layer, a machine needs extra CPU cycles to handle TCP traffic, and such configuration is not that fast as direct attach adapters .

Some time ago, IBM introduced the link aggregation feature. It allows trunk two physical adapters to a single logical device.

What is needed for such configuration

• two physical Ethernet adapters/ports, or two logical ports provisioned by SR-IOV adapters, or two interfaces delivered by two HEA’s
• the ports need to be connected to EtherChannel capable switch or switch pair. If you use two switches they must be configured in a Virtual Link Aggregation Group (VLAG) or Virtual Port Channel.
• only 1 public IP address

With this configuration you acquire

• Resilience – a system is connected thru independent adapters, switches
• Performance – both adapters are actively used to handle TCP traffic. If you use two adapters 1 Gb each, theoretically you get 2Gb bandwidth

Below you can see how to configure it

Here is an Lpar with two logical interfaces delivered by two independent SR-IOV adapters.

These ports looks following on the Green screen.

Create a Line Description type *AGG with the specific resources by command.

If your have ports correctly configures on switches, just add a IP address by ADDTCPIFC command. Vary on the interface and start use it.

In my humble opinion , if you don’t want use SEA, Link aggregation with SR-IOV adapters is the most efficient configuration.