In computer networking, a softwire protocol is a type of tunneling protocol that creates a virtual "wire" that transparently encapsulates another protocol as if it was an anonymous point-to-point low-level link. Softwires are used for various purposes, one of which is to carry IPv4 traffic over IPv6 and vice versa, in order to support IPv6 transition mechanisms.
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Softwire (protocol) Wikipedia(Text) CC BY-SA