IBM Support

MTU size change and failover reset cause vNIC interface to go into a reset loop

Flashes (Alerts)


Abstract

It is observed that a Maximum Transmission Unit (MTU) size change and failover might cause the virtual Network Interface Controller (vNIC) interface to reset in a loop. It can take up to 5 minutes or longer to restore the network connection.

Content

Linux releases affected:
Red Hat Enterprise Linux 8.1
Red Hat Enterprise Linux 8.2
Red Hat Enterprise Linux 8.4
SUSE Linux Enterprise Server 12, Service Pack 5
SUSE Linux Enterprise Server 15, Service Pack 1
SUSE Linux Enterprise Server 15, Service Pack 2
SUSE Linux Enterprise Server 15, Service Pack 3

IBM Systems Affected
All IBM Power Systems that support vNIC.

Description
MTU size change and failover can cause the IBM vNIC to go into a reset loop, taking 5 minutes or 
longer to restore the network connection. If the interface has multiple backing devices and auto 
priority failover is enabled, the number of resets worsen.

Workaround
- Avoid changing MTU unnecessarily
- Disable auto priority failover to avoid auto failback.

Fix Outlook
IBM is working closely with SUSE and Red Hat to release a fix for this issue. The fix should come as 
part of a future SLES or RHEL maintenance release. Please open a support ticket with SUSE or 
Red Hat if a hotfix is needed prior to the next maintenance release.

See Red Hat Bug: 2011995, 2014106
See SUSE Bug:  1191428

Product Synonym
Red Hat Enterprise Linux 8.1 or later
SUSE Linux Enterprise Server 12, Service Pack 5
SUSE Linux Enterprise Server 15, Service Pack 1, or later

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Document Information

Modified date:
22 October 2021

UID

ibm16490867