NAT Network Address Translation NAT 64 NAT 6

介紹 � NAT : 網路地址轉換(Network Address Translation) � NAT 64 (NAT 6 TO 4) : IPv 6轉IPv 4或IPv 4轉IPv 6。 � 術語: IPv 4 -converted IPv 6 addresses、 IPv 4 -embedded IPv 6 addresses、 IPv 4 -translatable IPv 6 addresses、 Network-Specific Prefix、 Well-Known Prefix 3

介紹 � IPv 4 -embedded � IPv 6 addresses in which 32 bits contain an IPv 4 address. � IPv 4 -converted IPv 6 addresses � IPv 6 addresses used to represent IPv 4 nodes in an IPv 6 network. � IPv 4 -translatable � IPv 6 addresses assigned to IPv 6 nodes for use with stateless translation. 4

介紹 � Network-Specific Prefix � an IPv 6 prefix assigned by an organization for use in algorithmic mapping. � Well-Known � the Prefix IPv 6 prefix defined in this document for use in an algorithmic mapping. 5

地址格式 � 包裝IPv 4 進IPv 6 � Concatenate the prefix, the 32 bits of the IPv 4 address, and the suffix to obtain a 128 -bit address. � Insert the null octet "u" at the appropriate position (bits 64 to 71), if the prefix length is less than 96 bits � 取出IPv 4 � If the prefix is 96 bits long, extract the last 32 bits of the. IPv 6 address � For the other prefix lengths, remove the "u" octet to obtain a 120 -bit sequence, then extract the 32 bits following the prefix. 6

Prefix � Well-Known � The Prefix Well-Known Prefix SHOULD be used in IPv 4 converted IPv 6 addresses � The Well-Known Prefix SHOULD NOT be used in IPv 4 - translatable IPv 6 addresses. � The Well-Known Prefix MAY appear in inter-domain routing tables � The Well-Known Prefix MUST NOT be used to represent non-global IPv 4 addresses 9

Prefix � Network-Specific � IPv 4 -translatable Prefixes IPv 6 addresses MUST use the selected Network-Specific Prefix. 10

Prefix (Stateless、stateful mapping) �Stateless mapping � IPv 4 -translatable IPv 6 addresses MUST use the selected Network-Specific Prefix. � Both IPv 4 - translatable IPv 6 addresses and IPv 4情境一 converted IPv 6 addresses SHOULD use the same prefix. � The stateless translation can be used for Scenario 1, Scenario 2, Scenario 5, and Scenario 6 情境二 11

Prefix (Stateless、stateful mapping) �Scenario 1 (IPv 6 network -> IPv 4 Internet) Scenario 2 (IPv 4 -> IPv 6) �an ISP holding a /32 allocation SHOULD use a /40 prefix, and a site holding a /48 allocation SHOULD use a /56 prefix. �Scenario 5 (IPv 6 -> IPv 4) Scenario 6 (IPv 4 -> IPv 6) � the 12 deployment SHOULD use a /64 or a /96 prefix.

Prefix �Both (Stateless、stateful mapping) on stateful mapping � The Well-Known Prefix SHOULD be used in these scenarios � All scenarios, the translation MAY use a Network-Specific Prefix � The Well-Known Prefix MUST NOT be used for Scenario 3 as this would lead to using the Well-Known Prefix with non-global IPv 4 addresses. 13

suffix � These bits are reserved for future extensions and SHOULD be set to zero. RFC 4291 14

參考資料 � RFC 6052 http: //tools. ietf. org/pdf/rfc 6052. pdf � 電腦王 http: //www. techbang. com/posts/15861 -3 -ipintroduction-to-network-architecture-conceptclassification-and-the-subnet-mask? page=2 � 維基百科 http: //zh. wikipedia. org/wiki/NAT � 中國教育和科研計算機網 http: //zh. wikipedia. org/wiki/NAT 15