Bug ID 429773: Session Initiation Protocol (SIP) flow control enforcement issues

Last Modified: Oct 06, 2020

Bug Tracker

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

Known Affected Versions:
11.2.0, 11.2.1, 11.3.0, 11.4.0, 11.4.1

Fixed In:
11.5.0, 11.4.1 HF2, 11.4.0 HF6, 11.3.0 HF9, 11.2.1 HF11

Opened: Sep 04, 2013
Severity: 3-Major
Related AskF5 Article:


When using Session Initiation Protocol (SIP) and Message-based Load Balancing (MBLB) and TCP/TLS you may encounter memory issues, due to ineffective flow control. When remote client/server drains much slower than the rate of messages queued for them, the pending messages could use more memory than necessary.


TMM could get into aggressive memory sweeper, often


SIP configured in a MBLB profile.


Increase the count of server-side connections to distribute messages.

Fix Information

The mblb profile's egress settings could control the egress pending Q size and prevents it from growing to a size that impacts performance of other connections.

Behavior Change