1.   Evolution of SR-IOV Technology

Single Root I/O Virtualization (SR-IOV) allows an I/O adapter to be virtualized into multiple Virtual Functions (VFs), which can be directly assigned to multiple logical partitions (LPARs). While this offers high performance, it comes with a limitation: no migration capability, since the logical port is directly attached to Logical Partition. To address this, vNIC (Virtual NIC) functionality introduces a layer of abstraction:

•         The logical port is assigned to VIOS (Virtual I/O Server).
•         The client adapter is then attached to the target LPAR.
•          This setup enables LPAR migration, as the VF is no longer directly tied to the partition.

2.   How to Configure Hybrid Network Virtualisation 

In this section we will navigate to the steps on configuring migratable logical port. As  Logical port directly assigned to partition offers superior performance, vNIC/vETH provides flexibility and migration support. Combining both technologies results in Hybrid Network Virtualization, balancing performance with mobility.

A.      Move the SR-IOV adapter to Shared Mode VIA HMC

    Select the CEC on HMC

1.          Go to Hardware Virtualized I/O tab
2.        Select the SR-IOV adapter from the drop-down list
3.         Click on the button Modify
4.          Window pops up “select Shared radio button”
5.          Once moved to Shared mode, it would display status of Physical ports of SR-IOV adapter as shown below:

B.      Assign migratable logical port via HMC to Logical Partition

Use the Hardware Management Console (HMC) to assign a Migratable Logical Port to an LPAR:

a.      Select the "Migratable" checkbox.

b.     Choose a Backup Device Type either of these:

                        I.         Virtual NIC Adapter

·       By default, HMC assigns a Virtual NIC backup device:

                                               i.         It configures a vNIC from the same adapter using a different port,

                                             ii.         From a different adapter’s port, if available.

                                           iii.         If multiple adapters are in shared mode, you can customize the backup device by clicking the “Backup Device Physical Location Code” text box.

                      II.         Virtual Ethernet Adapter

                                               i.         Select a Virtual Network that is on the same physical network as SR-IOV logical port.

                                             ii.         You can create a Shared Ethernet Adapter (SEA) using:

a.     A different SR-IOV adapter

b.     A standard Ethernet adapter

c.     A different physical port on the same adapter

                                           iii.         Once SEA is created, it can be selected as the Backup Device for the migratable logical port

          On AIX and Linux environments, when configuring a Migratable Logical Port,  The IP configuration is configured on an network interface and not on the network device (logical port (VF)). This design ensures that during live partition migration, all network traffic automatically fails over to the designated backup device, such as a virtual Ethernet adapter or vNIC. Once the migration completes and the VF is re-established on the destination system, traffic seamlessly resumes through the VF without manual intervention. Importantly, regardless of the backup device type selected during logical port creation, PHYP will automatically generate an EtherChannel on AIX or a Bonding device on Linux, and the IP must always be configured on these interfaces to maintain consistent connectivity and failover behaviour.

C.    Configuring network interface on AIX:

D.    Configuring network interface on Linux

E.      Verify Bond devices on Linux

F.       Migratable Logical Port on IBMi

In case of IBMi partition, VIPA channel to be configured manually, please find the below steps:

           i.                  VIPA configuration using IBMi console

       ii.                  Vary on and starttcpifc

    iii.                  Ping to ping partner

G.    Removal Of Migratable Logical Port

On AIX and IBM i (IBMi) systems, when a Migratable Logical Function is configured, it's necessary to detach the IP address (on AIX) or stop the RMVTCPIP interface (on IBMi) before attempting to remove the device through the Hardware Management Console (HMC). If this step is skipped, HMC will not permit deconfiguration of the MVF. Once the device is successfully removed via HMC, the associated EtherChannel on AIX or Bonding device on IBMi is automatically gets deleted. However, in the case of IBMi, the VIPA (Virtual IP Address) configuration must be manually removed to ensure a clean deconfiguration and prevent residual network bindings.

H.    How LPAR gets migrated with Migratable Logical Port Assigned:

        Assign migratable logical port to the LPAR as mentioned in above steps, In this step let us discuss on handling errors while doing migration with migratable logical port.

1.     vNIC as Backing Device When using a vNIC as the backup device, the HMC automatically configures it based on the availability of SR-IOV adapters on the destination CEC.

2.     vETH as Backing Device If a virtual Ethernet (vETH) is selected as the backup device, it is mandatory to pre-configure the virtual Ethernet network on the destination system. Failure to do so will result in validation errors during migration.

3.     Port-Specific Migration Using Labels To migrate a specific SR-IOV physical port, identical labels must be assigned to the corresponding ports on both the source and destination systems.

4.     Migration Window Configuration In the migration window, selecting “Virtual NIC Labels: Yes” enables label-based port mapping. Four override options are available to handle cases where the destination CEC lacks the required vNIC or SR-IOV configuration.

5.     Error Handling Without Overrides If override options are not selected and only “Yes” is chosen for Virtual NIC Labels, migration may fail with configuration errors due to missing or mismatched vNIC/SR-IOV setups on the destination system.

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