IBM Support

Physical port of the SR-IOV device is configured for devices to use jumbo frames

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Abstract

If you want to use jumbo frames, you must configure the single root I/O virtualization (SR-IOV) physical port of the device with a maximum transfer unit (MTU) size of 9000 bytes before you configure or create any virtual Network Interface Controller (vNIC) adapters.

Content

Linux Releases Affected
Red Hat Enterprise Linux® 8.1, and later
SUSE Linux Enterprise Server 15, Service Pack 1, and later
IBM Systems Affected
All IBM POWER9™ systems that support vNIC.
Symptoms
If you do not configure the SR-IOV physical port of the device with an MTU size of 9000 bytes, you might see the following message when you configure jumbo frames on the client interface:
# ip link set env5 mtu 9000
RTNETLINK answers: Invalid argument
`env5: Invalid MTU 9000 requested, hw max 1500
 

To enable jumbo frames, you must remove the vNIC adapters and then reconfigure the vNIC adapters after you update the MTU of the physical port.

Workaround

This workaround might result in a temporary loss of connection as it forces a device reset. The reset is triggered to make changes that apply across the vNIC stack.

You must run the following operations from the command line interface of the relevant VIOS partitions:
# oem_setup_env
# rmdev -l vnicserverX
# rmdev -l entY
# mkdev -l entY
# mkdev -l vnicserverX
Where, vnicserverX is the backing vNIC Server and  entY is the backing SR-IOV Virtual Function (VF) of the vNIC client.

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Product Synonym

Red Hat Enterprise Linux 8.1, and later
SUSE Linux Enterprise Server 15, Service Pack 1, and later

Document Information

Modified date:
03 June 2020

UID

ibm16212125

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