Bug ID 881041: BIG-IP system may forward IP broadcast packets back to the incoming VLAN interface via a forwarding virtual server.

Last Modified: Dec 18, 2024

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

Known Affected Versions:
14.1.2.3, 14.1.2.4, 14.1.2.5, 14.1.2.6, 14.1.2.7, 14.1.2.8, 14.1.3, 14.1.3.1, 14.1.4, 14.1.4.1, 14.1.4.2, 14.1.4.3, 14.1.4.4, 14.1.4.5, 14.1.4.6, 14.1.5, 14.1.5.1, 14.1.5.2, 14.1.5.3, 14.1.5.4, 14.1.5.6, 15.1.0, 15.1.0.1, 15.1.0.2, 15.1.0.3, 15.1.0.4, 15.1.0.5, 15.1.1, 15.1.2, 15.1.2.1, 15.1.3, 15.1.3.1, 15.1.4, 15.1.4.1, 15.1.5, 15.1.5.1, 15.1.6, 15.1.6.1, 15.1.7, 15.1.8, 15.1.8.1, 15.1.8.2, 15.1.9, 15.1.9.1, 15.1.10, 15.1.10.2, 15.1.10.3, 15.1.10.4, 15.1.10.5, 15.1.10.6

Opened: Feb 14, 2020

Severity: 3-Major

Symptoms

Some received packets are retransmitted back on the incoming VLAN interface.

Impact

Broadcast packets are forwarded back to the incoming VLAN interface might result in loops if there are multiple gateways on the network.

Conditions

The symptom is found with the following conditions: 1. A forwarding virtual server is configured. 2. A packet is received whose destination MAC address is its unicast VLAN MAC address and the destination IP address is the broadcast address of that subnet.

Workaround

Apply an iRule to network-forwarding virtual servers that drops packets destined to the broadcast IP address of local vlans. For example: ltm data-group internal /Common/local_broadcast_ips { records { 10.1.1.255/32 { } 10.1.2.255/32 { } } type ip } ltm rule do_not_fwd_to_bcast_addrs { priority 5 when CLIENT_ACCEPTED { if { [class match [IP::local_addr] equals local_broadcast_ips ] } { drop } } }

Fix Information

None

Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips