ication, then the UE can bypass the PGW at the user plane. Obviously IP packets still flow through the PGW, but they are not destined to it, thus the PGW has to actively inspect every user plane IP packet that goes through it. This might not be desirable from the IP forwarding efficiency point of view. If the PGW assumes the role of a DHCPv6 server-client, the UE would always send packets first to the PGW address, with or without unicast communication being allowed. The use of the DHCP is tightly coupled with the establishment of a PDN Connection. The use of DHCP in 3GPP networks has been limited SO far, which is visible in the lack of details learned from live deployments in relevant 3GPP standards (as in Release-11 at least). The DHCP protocol over the (S)Gi-interface is available for both transparent and non-transparent access to the PDN, and used solely for IP address management and additional end host configuration (such as configuring DNS and P-CSCF server addresses). Section 4.4 discusses IP address management and also links the use of the DHCP protocol over (S)Gi-interface to it. Figure 4.11 shows possible DHCP protocol interactions over the (S)Gi-interface triggered by the management of the PDN Connection. Currently, 3GPP specifications are silent about DHCP server initiated end host reconfiguration, but there is no reason why a vendor product could not implement such, for example, to delete a PDN Connection. It should be noted that both AAA and DHCP can be used simultaneously over the (S)Gi-interface. One example would be using AAA for a PDN Connection authentication/authorization and then DHCP for IP address management. Another example would be using AAA for accounting purposes while DHCP is, again, used for the UE IP address management. IPv6 in 3GPP Networks SGSN/SGW GGSN/PGW DHCP Server Create PDP Context Request or Create Session Request or PBU Gateway as a DHCP Client requests for IPv4 address or IPv6 prefix DHCPDISCOVER or SOLICIT DHCPOFFER or ADVERTIZE Not used if Rapid DHCPREQUEST or Commit is u