Why is the filtering rule configured by the NE40E security device in the blocking mode invalid?
The NE40E security device is mainly used for connecting the domestic and international routers, blocking and filtering invalid packets. When the service board for transparent transmission on the NE40E is POS, the link layer protocol configured on the NE40E is HDLC, but the link layer protocol configured at the interfaces of the local and peer devices is PPP, the packets can be transparently transmitted normally. Because the link layer protocols configured at the interfaces of the local and peer devices are different, the structures of the packet heads are different. Thus, the system cannot identify the packets transmitted transparently. That is why the filtering rule is invalid.