Bug ID 588572: Unnecessary re-transmission of packets on higher ICMP PMTU.

Last Modified: Apr 10, 2019

Bug Tracker

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

Known Affected Versions:
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, 11.6.0, 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:
11.5.4 HF3

Opened: Apr 19, 2016
Severity: 4-Minor

Symptoms

LTM re-transmits TCP segments even when ICMP Path maximum transmission unit (PMTU) is higher than existing MTU.

Impact

Burst traffic generated.

Conditions

ICMP PMTU is higher than existing MTU. User enables MPTCP, Rate Pacing, or any of the following congestion controls: Vegas, Illinois, Woodside, CHD, CHG

Workaround

Disable Path MTU Discovery by entering the command: tmsh modify sys db tm.enforcepathmtu value disable.

Fix Information

Fixed unnecessary re-transmission of packets on higher ICMP Path maximum transmission unit (PMTU) in the advanced TCP implementation.

Behavior Change