GRE packet decapsulation process on the USG6000

1. Upon receiving an IP packet over the physical port connected to the Internet, the firewall checks the destination address of the packet. If the destination address is the firewall address and the protocol number in the IP packet header is 47 (indicating an encapsulated GRE packet), the firewall removes the IP packet header and enables the GRE protocol processing part to process the packet. 2. After checking and recognizing keywords, the GRE protocol processing part removes the GRE packet header and enables the IP processing part to process the packet. 3. The IP processing part forwards the packet to the IP network.

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