Bug ID 589822: Setting the masquerade MAC on a traffic-group to a multicast address can result in unexpected network behavior

Last Modified: Sep 13, 2023

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

Known Affected Versions:
11.5.3, 11.5.4, 11.5.5, 11.5.6, 11.5.7, 11.5.8, 11.5.9, 11.5.10, 11.6.0, 11.6.1, 11.6.2, 11.6.3,,,,, 11.6.4, 11.6.5,,,, 12.0.0, 12.0.0 HF1, 12.1.0 HF1, 12.0.0 HF2, 12.1.0 HF2, 12.0.0 HF3, 12.0.0 HF4, 12.1.1 HF1, 12.1.1 HF2, 12.1.2 HF1, 12.1.2 HF2, 12.1.0, 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

Opened: Apr 27, 2016

Severity: 4-Minor


The BIG-IP system allows the Masquerade MAC to be set to an Ethernet multicast address, which may cause traffic intended for an Active BIG-IP to be flooded to all devices on the local network.


Depending on the behavior and configuration of devices on your network: - Excessive traffic may be flooded to all devices on your network - Traffic may not be delivered correctly to the Active BIG-IP device - ARP resolution may fail for failover objects


You have configured MAC Masquerade with a multicast address. Multicast addresses are defined by having the lowest bit in the first octet set. For example, the following address: 00:01:d7:ab:cd:ef has a first octet which is: 00000000 in binary. With the lowest bit flipped: 00000001 it becomes: 01:01:d7:ab:cd:ef


Choose a unicast (non-multicast) address for MAC Masquerade. SOL3523 contains recommendations for choosing a safe MAC Masquerade address.

Fix Information


Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips