Bug ID 681673: tmsh modify FDB command permits multicast MAC addresses, which produces unexpected results

Last Modified: Sep 13, 2023

Affected Product(s):
BIG-IP LTM(all modules)

Known Affected Versions:
12.1.1, 12.1.2, 12.1.3,,,,,,,, 12.1.4,, 12.1.5,,,, 12.1.6, 13.0.0, 13.0.0 HF1, 13.0.0 HF2, 13.0.0 HF3, 13.0.1, 13.1.0,,,,,,,,, 13.1.1

Fixed In:

Opened: Sep 05, 2017

Severity: 3-Major


TMSH does not block modify FDB commands that add a multicast MAC addresses.


There is not enough information to map the outgoing MAC address to a multi-cast group, and therefore it gets a default entry added that has no ports mapped. The result is that the frame will not go out the interface indicated in the tmsh command yet no warning is provided.


This occurs when the following is configured using tmsh commands when the mac-address is multicast: fdb vlan <vlan> records add {<mac-address> {interface <slot>/<port>}}.



Fix Information

TMSH modify FDB command is no longer permitted to add multicast MAC addresses, so this issue no longer occurs.

Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips