Bug ID 1207977: Packet loss on VELOS due to congestion caused by interfaces that are down or disabled

Last Modified: May 29, 2024

Affected Product(s):
F5OS Velos(all modules)

Known Affected Versions:
F5OS-C 1.3.0, F5OS-C 1.3.1, F5OS-C 1.3.2, F5OS-C 1.5.0, F5OS-C 1.5.1

Fixed In:
F5OS-C 1.6.0

Opened: Dec 09, 2022

Severity: 3-Major


An interface that is down or disabled can cause dropped packets on another port due to internal congestion. This leads to bi-directional packet loss that affects tenants. The packet drops due to VOQ congestion can be seen in the vqf_voq tmctl table in the cos_fill_drop column.


Congestion occurs, which causes packet loss that also affects tenants.


VELOS chassis. One or more interfaces on a blade in a partition is down or disabled. Packets generated internally like lldp packets being sent to a down or disabled interface.


The mitigation is to disable sources of internally generated packets which are sent to a down or disabled interface. This can be done by disabling LLDP on a down or disabled interface.

Fix Information

This change will disable queueing packets to a down or disabled interface queue. This will prevent the internal congestion and dropped packets.

Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips