Bug ID 700827: B2250 blades may lose efficiency when source ports form an arithmetic sequence.

Last Modified: Jun 20, 2019

Bug Tracker

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

Known Affected Versions:
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, 12.1.2 HF1, 12.1.2 HF2, 12.1.3,,,,,,,, 13.0.0, 13.0.0 HF1, 13.0.0 HF2, 13.0.0 HF3, 13.0.1, 13.1.0,,,,,,,,, 13.1.1,,,, 14.0.0,,,,

Fixed In:
14.1.0,,, 12.1.4

Opened: Jan 04, 2018
Severity: 3-Major


Traffic imbalance between tmm threads. You might see the traffic imbalance by running the following command: tmsh show sys tmm-traffic


Traffic imbalance between tmm threads may result in sub-optimal performance.


Source ports used to connect to B2250 blade form an arithmetic sequence. For example, some servers always use randomly selected even source port numbers. This means the 'stride' of the ports selected is '2'. Because a sorted list of the ports yields a list like 2, 4, 6, 8... 32002, 32004. It is 'striding' over the odd ports; thus, a port stride of 2.


Randomize source ports when connecting via a BIG-IP system.

Fix Information

This release introduces a new variable mhdag.pu.table.size.multiplier. Setting it to 2 or 3 mitigates the issue.

Behavior Change