Method, system and equipment for allocating IPv6 (internet protocol version 6) prefixes

The invention discloses a method for allocating IPv6 (internet protocol version 6) prefixes, which comprise the following steps of: querying a downlink port prefix corresponding to uplink port prefix information in a router advertisement message according to correspondence relation between an uplink port prefix and the downlink port prefix in port configuration information which is received by network node equipment and acquired locally in advance, and then sending the router advertisement message carrying the corresponding downlink port prefix to user equipment so as to realize global IPv6 address configuration, wherein the whole process needes no insertion of new options, and the expense on address configuration can be reduced. The invention also discloses an IPv6 prefix allocating system and the network node equipment.