Symptoms
In some cases, an active BIG-IP may fail to forward the SYN on the server-side when handling traffic for a mirrored FastL4 virtual after receiving a context ACK from the standby BIG-IP.
Symptoms include:
-- TCP connection failures.
-- Possibly other packets lost.
Impact
FastL4 mirroring does not always forward SYN to server after receiving context ACK. Connections fail.
Conditions
-- FastL4 virtual server.
-- Mirroring is enabled.
-- Certain traffic interleaving might be necessary for this intermittent problem to occur.
Workaround
Set the tm.fastl4_ack_mirror db variable using the following command:
tmsh modify sys db tm.fastl4_ack_mirror value disable
Fix Information
In this release, mirrored FastL4 virtual servers now forward the SYN on the server-side after receiving the context-ack from the peer as expected.
