4in6

{{Short description|Tunneling of IPv4 in IPv6}}

{{IPv6 transition mechanisms}}

{{Use dmy dates|date=September 2022}}

4in6 refers to tunneling of IPv4 in IPv6.{{cite book|last1=Blanchet|first1=Marc|title=Migrating to IPv6: A Practical Guide to Implementing IPv6 in Mobile and Fixed Networks|date=18 May 2009|publisher=John Wiley and Sons|isbn=9780470468906|pages=345–350|url=https://books.google.com/books?id=9_Qn3LSD2t8C&pg=PA345|language=en}}{{cite book|last1=Stockebrand|first1=Benedikt|title=IPv6 in Practice: A Unixer's Guide to the Next Generation Internet|date=28 November 2006|publisher=Springer Science & Business Media|isbn=9783540480013|pages=170–172|url=https://books.google.com/books?id=VpHSCntF6JEC&pg=PA170|language=en}} It is an Internet interoperation mechanism allowing Internet Protocol version 4 (IPv4) to be used in an IPv6 only network. 4in6 uses tunneling to encapsulate IPv4 traffic over configured IPv6 tunnels as defined in {{IETF RFC|2473}}.{{cite journal|last1=Conta|first1=Alex|last2=Deering|first2=S.|title=RFC 2473: Generic Packet Tunneling in IPv6 Specification|url=https://tools.ietf.org/html/rfc2473|website=tools.ietf.org|year=1998 |doi=10.17487/RFC2473 |access-date=17 June 2016}} 4in6 tunnels are usually manually configured but they can be automated using protocols such as TSP to allow easy connection to a tunnel broker.{{cite book|last1=Hagen|first1=Silvia|title=Ipv6 Essentials|date=9 June 2014|publisher="O'Reilly Media, Inc."|isbn=9781449335267|pages=228–231|url=https://books.google.com/books?id=rTbFAwAAQBAJ&pg=PA228|language=en}}