Symptoms

The High-Speed Bridge (HSB) can lock up in certain vlangroup configurations. HSB lock messages appear and the BIG-IP system eventually reboots, causing all traffic flows to be lost.

Impact

TMM goes down.

Conditions

Large ping messages to get re-assembled but when vlangroup.flow.allocate is disabled, tmm can write whole big message to HSB and that messes up internal state.

Workaround

Set vlangroup.flow.allocate to enabled with 11.4.0 you can limit bigger ICMP with dos.maxicmpframesize

Fix Information

ICMP messages are no longer reassembled when going through vlan group and original fragmentation is preserved.

Behavior Change