Tunneling-IPv6 tunnel communication (1)

IPv6 tunnel Communication Technology
IPv6 is a new generation of Internet communication protocol with many features: new Header Format, large address space, effective and hierarchical address and routing architecture, built-in security, new communication Protocol Neighbor Discovery Protocol for IPv6 that interacts with neighboring nodes, scalability. As a network manager, it is necessary to enhance understanding of IPv6 and prepare for the full upgrade of IPv4 in the future.
The IPv6 tunnel encapsulates IPv6 packets in IPv4 packets so that IPv6 packets can communicate through the IPv4 network. For devices using tunnel technology, IPv6 datagram is encapsulated into IPv4 at the entrance of the tunnel. The source and destination addresses of IPv4 packets are the IPv4 addresses at the entrance of the tunnel and at the exit of the tunnel respectively; at the exit of the tunnel, the IPv6 packet is taken out and forwarded to the destination node. Tunnel Technology only requires modification at the entrance and exit of the tunnel. It is easy to implement because it has no requirements on other parts. However, tunnel technology cannot directly communicate with IPv4 hosts and IPv6 hosts.
IPv6-over-IPv4 GRE Tunneling Technology
Using the standard GRE tunneling technology, IPv6 data packets can be carried over IPv4 GRE tunnels. The GRE tunnel is a connection between two points. Each connection is a separate tunnel. The GRE tunnel uses IPv6 as the passenger protocol and GRE as the bearer protocol. The configured IPv6 address is configured on the Tunnel interface, and the configured IPv4 address is the Tunnel source address and destination address Tunnel start and end ).
The GRE tunnel is mainly used for regular and secure communication between two edge routers or terminal systems and edge routers. Vrouters and terminal systems must implement dual-protocol stacks.

 
Figure 1 GRE Principle
 
Figure 2 GRE packet Encapsulation Format

As shown in figure 1, the two IPv6 subnets are Group1 and Group2, respectively. They must be interconnected through the IPv6 tunnel protocol between router R1 and R2. The tunnel interfaces of R1 and R2 are manually configured Global IPv6 addresses, and the tunnel source and destination addresses must also be manually configured. Set the IPv4 address of the E0 interface of R1 to 192.168.100.1, And the IPv4 address of the E0 interface of R2 to 192.168.200.1.
During the above forwarding process, the R1 router first learns the destination address 3003: 1 through the tunnel Based on the route table, so the packet is sent to the tunnel interface for encapsulation according to the specific GRE Format 2.