IPv6: The Next Generation Internet Protocol
A practical, hands-on guide to the new version of the Internet Protocol, written for network administrators and managers who will work with IPv6.
TABLE OF CONTENTS IPv6: The Next Generation Internet Protocol
Section 1.8: TRANSITION TECHNIQUES
1.8 TRANSITION TECHNIQUES
One technique involves IPv6-over-IPv4 tunneling which involves encapsulating IPv6 packets within IPv4 in order for them to be conveyed across IPv4 routing infrastructures. One aspect involves configured tunneling which involves IPv6 over IPv4 tunneling where the IPv4 tunnel endpoint address is designated by configuration information on the encapsulating node.
However, automatic tunneling is a method where IPv6-over-IPv4 tunneling involves the IPv4 tunnel endpoint address to be designated from the IPv4 address within in the IPv4-compatible destination address of the IPv6 packet.
Addressing
The automatic tunneling mechanism employs a specific type of IPv6 address. It is designated as an IPv4-compatible address. An IPv4-compatible address is designated by an all zeros 96-bit prefix, and contains an IPv4 address in the low order 32-bits. Various IPv6 addressing formats are compared in Figure 1.8.
IPv4/IPv6 Address Format
IPv4 compatible addresses are reserved for IPv6/IPv4 nodes which handle automatic tunneling. Nodes that are configured with IPv4 compatible addresses may employ the total address as their IPv6 address can use the embedded IPv4 address as their IPv4 address.
The rest of the IPv6 address space which designates all addresses with 96-bit prefixes besides that of 0:0:0:0:0:0 are designated as IPv6-only Addresses.
The dual IP layer is the most direct method for IPv6 nodes to stay compatible with IPv4 only nodes. It provides a total IPv4 implementation. IPv6 nodes which yield a total method of IPv4 implementation besides that of their IPv6 implementation are designated as IPv6/IPv4 nodes. IPv6/IPv4 nodes have the capability to...
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