Bug ID 563475: ePVA dynamic offloading can result in immediate eviction and re-offloading of flows.

Last Modified: Nov 07, 2022

Bug Tracker

Affected Product:  See more info
BIG-IP All(all modules)

Known Affected Versions:
11.5.0, 11.5.1, 11.5.1 HF1, 11.5.1 HF10, 11.5.1 HF11, 11.5.1 HF2, 11.5.1 HF3, 11.5.1 HF4, 11.5.1 HF5, 11.5.1 HF6, 11.5.1 HF7, 11.5.1 HF8, 11.5.1 HF9, 11.5.10, 11.5.2, 11.5.2 HF1, 11.5.3, 11.5.3 HF1, 11.5.3 HF2, 11.5.4, 11.5.4 HF1, 11.6.0, 11.6.0 HF1, 11.6.0 HF2, 11.6.0 HF3, 11.6.0 HF4, 11.6.0 HF5, 11.6.0 HF6, 11.6.0 HF7, 11.6.0 HF8, 12.0.0, 12.0.0 HF1, 12.0.0 HF2

Fixed In:
12.1.0, 12.0.0 HF3, 11.6.1, 11.5.4 HF2

Opened: Dec 17, 2015
Severity: 3-Major
Related Article:
K00301400

Symptoms

ePVA dynamic offloading can result in immediate eviction and re-offloading of flows. If dynamic offloading is enabled in the fastl4 profile, flows that collide in the ePVA will ping/pong in and out of the ePVA due to immediate eviction and re-offloading. Flows that are evicted due to collisions are reported in the epva_flowstat stats, tot.hash_evict.

Impact

Flows that collide will be re-offloaded, evicted, and then re-offloaded again within a short time span. It is unknown if there is a direct impact, but in some cases a delay in processing packets on a connection may occur.

Conditions

A fastl4 profile with PVA Offload Dynamic enabled and two flows that result in a hash collision, resulting in an evicted flow.

Workaround

Disable PVA Offload Dynamic in the fastl4 profile. Another option would be to disable PVA Flow Evict in the fastl4 profile.

Fix Information

The system now handles flows involved in hash collisions such that ePVA dynamic offloading no longer results in immediate eviction and re-offloading of flows.

Behavior Change