Transparent NAT Between IPv6 and IPv4

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Transparent NAT Between IPv6 and IPv4

• Pedro Roqueroque_at_cisco.com

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Transparent NAT
IPv6
IPv4
IPv6 Host
IPv4 Host

• Transparent to hosts
• Bidirectional
• Access from the IPv6 cloud to IPv4 servers
• Access from the IPv4 cloud to IPv6 servers

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Advantages

• It effectively expands the address space as a
  small number of IPv4 addresses can serve an IPv6
  cloud
• Translation router can be placed anywhere on the
  network
• Upper layer protocol translation

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IPv6 Client to IPv4 Server
50003000abcd1234/128 to 192.2.3.4/128 source
address pool10.0.0.0/8
IPv4 Host
IPv6
IPv6 Host
IPv4 Internet
5f006d00000ffff0/96 to 0.0.0.0/0 source
address pool 171.69.0.0/28
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IPv4 Client to IPv6 Server
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Implementation

• Cisco has made a prototype available at the end
  of July 97
• Translates
• Regular TCP/UDP
• FTP (RFC 959) from/to FOOBAR (RFC 1639)
• ICMP echo
• ICMP error messages

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Summary

• Equivalent solution to the deployed IPv4 NAT
  solutions, in terms of benefits and drawbacks
• Transparent NAT doesnt require explicit IETF
  standardization effort
• IETF could revise protocols like FTP to make
  them more translation friendly