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6to4 tunnel
6to4 is an automatic tunneling technology that enables communication between isolated IPv6
islands and between sites within the IPv6 backbone and IPv6 backbone networks without the
network operator providing IPv6 interconnection services.
The 6to4 tunnel technology is used to establish a tunnel between border routers at an IPv6 site.
The border router at the source site is the start node of the tunnel, and the border router at the
destination site is the end point of the tunnel.
The 6to4 tunnel technology uses a special IPv6 address, that is, a 6to4 address, which starts with
2002. The IPv4 address of the border router is embedded in the prefix of this address. The address
structure is shown in the figure below.
− FP: Format Prefix, which is 001
− TLA: Top Level Aggregator, which is 0x0002
− IPv4 address: The IPv4 address of the border router
− SLA ID: Site Level Aggregator, namely the ID of subnet
− Interface ID: The ID of the interface
6rd tunnel
6RD (IPv6 Rapid Deployment) is an IPv6 network transition technology solution developed on the
basis of 6to4. It adds a 6RD BR (Border Relay, Border Relay Device) to an existing IPv4 network,
establishes a 6in4 tunnel at the home gateway (6RD CE (Customer Edge)) and 6RD BR of IPv6 users,
and provides IPv6 access to users.
The 6RD network typology is as follows.
As shown in the figure above, the 6RD tunnel technology is used to implement mutual access
between IPv6 islands, and the BR can also be used to access the IPv6 network after the BR.
The main differences between 6RD and 6to4:
6RD does not need to use a specific address 2002::/16, it can use the network operator's own
address block, which greatly increases the convenience of implementation.