Bug ID 589400: With Nagle disabled, TCP does not send all of xfrags with size greater than MSS.

Last Modified: Oct 12, 2018

Bug Tracker

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

Known Affected Versions:
11.2.1, 11.3.0, 11.4.0, 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, 11.6.0, 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, 12.0.0, 12.0.0 HF1, 12.0.0 HF2, 12.0.0 HF3, 12.0.0 HF4, 12.1.0, 12.1.0 HF1, 12.1.0 HF2, 12.1.1, 12.1.1 HF1, 12.1.1 HF2, 12.1.2

Fixed In:
13.0.0, 12.1.2 HF1, 11.6.3.3, 11.5.7

Opened: Apr 25, 2016
Severity: 3-Major
Related AskF5 Article:
K33191529

Symptoms

With Nagle disabled, TCP does not send all of xfrags with size greater than MSS.

Impact

Additional connection latency.

Conditions

Congestion window is small relative to message size; abc is enabled; also might manifest when serverside MTU is greater than clientside MTU.

Workaround

Enabling proxy-mss on the serverside TCP profile significantly reduces incidence of this problem in observed cases. If init-cwnd is low, raising it might also help. Disabling abc can also reduce the problem, but might have other negative network implications.

Fix Information

Incoming packets are now pulled more aggressively into the send buffer, if there are no negative implications for CPU performance.

Behavior Change