Bug ID 442098: Avoid Head-of-line blocking by enabling egress queue discard limits.

Last Modified: Apr 10, 2019

Bug Tracker

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

Known Affected Versions:
11.4.1, 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, 11.5.2, 11.5.2 HF1, 11.5.3, 11.5.3 HF1, 11.5.3 HF2, 11.5.4, 11.5.4 HF1, 11.5.4 HF2, 11.5.4 HF3, 11.5.4 HF4, 11.5.5, 11.5.6, 11.5.7, 11.5.8, 11.5.9, 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, 11.6.1, 11.6.1 HF1, 11.6.1 HF2, 11.6.2, 11.6.2 HF1, 11.6.3, 11.6.3.1, 11.6.3.2, 11.6.3.3, 11.6.3.4, 11.6.4

Fixed In:
11.4.1 HF3

Opened: Jan 03, 2014
Severity: 2-Critical
Related AskF5 Article:
K16373

Symptoms

For a lossless mode switch configuration associated with ingress buffering, there is a potential for the switch to experience head-of-line blocking during periods of egress contention/congestion, where lower ingress limits may result in ingress dropping of sensitive traffic. This affects the following platforms; PB200, 11000, 11050, B2100, 5000, 7000.

Impact

Traffic over the high speed 1 GB link gets impacted by buffering on the low speed 10 MB link.

Conditions

This might occur when the system sends logging data at a speed higher than the physical interface to the logging server can support, for example 50Mbps of HSL to a 10Mbps ethernet link.

Workaround

None

Fix Information

Avoid head-of-line-blocking (or lossless mode) with CoS queue dropping by enabling mmu queue egress limit thresholds.

Behavior Change