A presale test usually incorporates a performance test. It is recommended to disable the sequence preserving function and statistic function on a firewall for such a performance test so that the firewall can present its optimal performance. To make sure that functions such as anti-attack and querying session quantity work normally, usually you are not advised to disable the statistic function. However, the sequence preserving function can be disabled usually. To disable the sequence preserving function, run the undo firewall fifo enable command.
The sequence preserving function sorts packets before the firewall forwards packets. It ensures that packets are sent in order, preventing failure of some applications in responding to disordered packets. If some RADIUS servers cannot sort packets, the firewall must ensure the packet sequence.
If the firewall is not deployed in a special zone to protect servers, it is not necessary to enable the sequence preserving function.