USG2100（V100R005） changed the 3 layer interface to 2 layer, accede to untrust area, accede internal network 2 layer interface to trust area, accede the two interfaces to the same VLAN, all the packet filtering is forbidden.
PC1----trust firewall untrust----PC2
PC1 can communicate with PC2 too.
Forbid all the packet filtering, don’t accede interface to the area. PC1 can communicate with PC2, data is not processed by CPU. Shutdown the overall fast forwarding, PC1 cannot ping PC2, the command is: undo l2fwdfast enable.
Open the fast forwarding function overall, packets do not pass over packet filtering by soft packet. (switch board card is not controlled by packet filtering )
The feature of new version relates to the packets processing flow.