Bug ID 1670437: Jumbo frames with an IP length greater than 9174 bytes may be dropped

Last Modified: May 05, 2025

Affected Product(s):
F5OS F5OS-C(all modules)

Known Affected Versions:
F5OS-C 1.6.2

Fixed In:
F5OS-C 1.8.0

Opened: Sep 13, 2024

Severity: 3-Major

Symptoms

Jumbo frames with an IP total length greater than 9174 bytes are dropped when traversing the VELOS inter-blade backplane.

Impact

Data transfers between a VELOS tenant and another host configured with the same MTU may be disrupted. Individual packets may be dropped, or some flows may be permanently dropped.

Conditions

This issue may occur for VELOS tenants with a VLAN MTU set to 9175 or higher.

Workaround

Do not set the VLAN MTU higher than 9174 on a VELOS tenant.

Fix Information

The MTU limit of the inter-blade backplane has been increased to align with the maximum supported size of jumbo frames, ensuring that jumbo frame communication is reliably transmitted without packet drops.

Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips