Flashes (Alerts)
Abstract
Bridge mode networking is not supported for VIOS-backed Virtual Ethernet (VETH) interfaces. This limitation occurs because VETH interfaces use a fixed, burned-in source MAC address. As a result, any Ethernet packet with a mismatched source MAC address is dropped, leading to an error on the host operating system.
Content
Linux Releases Affected
All Linux Kernels that support running a KVM guest in a PowerVM LPAR that is Linux kernel versions 6.7+ and PowerVM FW1011+
IBM Systems Affected
All PowerVM versions that support running a KVM guest in a PowerVM LPAR that is Linux kernel versions 6.7+ and PowerVM FW1011+
Symptoms
The bridge network does not function correctly for guest virtual machines. Guests are unable to obtain IP addresses, DNS configurations, or routing information, and fail to acquire DHCP leases. The following errors are reported in the kernel logs of the host system:
[ T8420] kvm-hv: Parent hypervisor does
[ T8351] br0: port 2(vnet0) entered blocking state
[ T8351] br0: port 2(vnet0) entered forwarding state
[ T8953] ibmveth 30000002 env2: tx: h_send_logical_lan failed with rc=-4Workaround
Using VNICs instead of VETH interfaces can prevent this issue.
Fix Outlook
SUSE mirrored bug number: SUSE1249420
The fix for this issue will be included in a later release.
References
I/O device impacted
vETH interfaces that are assigned to an LPAR and backed by VIOS.
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Document Information
Modified date:
10 November 2025
UID
ibm17247967