Bug ID 504827: Use of DHCP relay virtual server might result in tmm crash 'top filter'.

Last Modified: Oct 06, 2020

Bug Tracker

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

Known Affected Versions:
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, 11.5.10, 11.5.2, 11.5.2 HF1, 11.5.3, 11.5.3 HF1, 11.5.3 HF2

Fixed In:
11.5.4

Opened: Feb 04, 2015
Severity: 3-Major
Related AskF5 Article:
K17186

Symptoms

The Traffic Management Microkernel (TMM) may produce a core file with the 'Assertion "top filter" failed' error message. As a result of this issue, you may encounter one or more of the following symptoms: Your BIG-IP system fails over to the standby system if configured for HA. Messages similar to the following example are logged to the /var/log/tmm* files: notice panic: ../modules/hudfilter/hudnode.c:310: Assertion "top filter" failed. Messages similar to the following example are logged to the /var/log/ltm file: notice sod[8810]: 01140045:5: HA reports tmm NOT ready. Messages similar to the following example are logged to the /var/log/messages file: notice logger: Started writing core file: /var/core/tmm.0.bld2384.0.core.gz for PID 13897 notice logger: Finished writing 236194271 bytes for core file: /var/core/tmm.0.bld2384.0.core.gz for PID 13897 Your BIG-IP system generates TMM core files to the /var/core directory, with a time stamp that correlates to the traffic interruption, similar to the following example: -rw-r--r-- 1 root root 226M Apr 13 15:09 tmm.0.bld2384.0.core.gz

Impact

The BIG-IP system may temporarily fail to process traffic as it recovers from TMM restarting, and systems configured as part of a high availability (HA) group may fail over. Traffic disrupted while tmm restarts.

Conditions

This issue occurs when the following condition is met: A Dynamic Host Configuration Protocol (DHCP) relay virtual server and another BIG-IP virtual server are both configured to use the same IP address and port combination.

Workaround

Avoid configuring virtual servers that share address:port with DHCP relay virtual server. In releases prior to version 11.5.4, use regular IP forwarding virtual servers if the virtual server is not for Relay but just for 'forwarding'. When the virtual server destination is not 255.255.255.255, it is typically for forwarding, not for Relay.

Fix Information

Verify existing serverside flows are actual relay flows before reusing it.

Behavior Change