1.2. Assumptions......................................... 7 1.3. Impact Outside the Network Layer.................... 7 2. Terminology.............................................. 8 2.1. Addresses........................................... 9 2.2. Requirements........................................ 9 3. Translating from IPv4 to IPv6............................ 9 3.1. Translating IPv4 Headers into IPv6 Headers.......... 11 3.2. Translating UDP over IPv4........................... 13 3.3. Translating ICMPv4 Headers into ICMPv6 Headers...... 13 3.4. Translating ICMPv4 Error Messages into ICMPv6....... 16 3.5. Knowing when to Translate........................... 16 4. Translating from IPv6 to IPv4............................ 17 4.1. Translating IPv6 Headers into IPv4 Headers.......... 18 4.2. Translating ICMPv6 Headers into ICMPv4 Headers...... 20 4.3. Translating ICMPv6 Error Messages into ICMPv4....... 22 4.4. Knowing when to Translate........................... 22 5. Implications for IPv6-Only Nodes......................... 22 6. Security Considerations.................................. 23 References................................................... 24 Author's Address............................................. 25 Full Copyright Statement..................................... 26
1. Introduction and Motivation
The transition mechanisms specified in [TRANS-MECH] handle the case of dual IPv4/IPv6 hosts interoperating with both dual hosts and IPv4-only hosts, which is needed early in the transition to IPv6. The dual hosts are assigned both an IPv4 and one or more IPv6 addresses. As the number of available globally unique IPv4 addresses becomes smaller and smaller as the Internet grows there will be a desire to take advantage of the large IPv6 address and not require that every new Internet node have a permanently assigned IPv4 address.
There are several different scenarios where there might be IPv6-only
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