Pv4 1 octet In case of IPv6 16 octets of IPv6 address prefixlen Figure 4.14 The PDN Address Allocation information element carrying GPRS Tunneling Protocol version 2 (GTPv2) IP addressing information. IPv6 in 3GPP Networks User Datagram Protocol, Src Port gtp-control (2123), Dst Port gtp-control (2123) GPRS Tunneling Protocol V2 Create Session Response Flags: 72 Message Type: Create Session Response (33) Message Length: 123 Tunnel Endpoint Identifier: 1912602635 Sequence Number: 1 Spare: 0 D Cause : Fully Qualified Tunnel Endpoint Identifier (F-TEID) : PDN Address Allocation (PAA) : IE Type: PDN Address Allocation (PAA) (79) IE Length: 22 = CR flag: o 0000 = Instance: o 011 = PDN Type: IPv4/IPv6 (3) IPv6 Prefix Length: 64 PDN IPv6: fc00:6:8000: :1 (fc00:6:8000::1) PDN IPv4: 10.254.0.29 (10.254.0.29) 66 c8 2c 5e 00 04 00 Text item (text), 26 bytes Packets: 1636 Displayed: 1636 Marked: 0 Figure 4.15 A captured PDN Address Allocation information element carrying GTPv2 IPv4 and IPv6 addressing information. Octets Type = 0x63 Length (1 for now) Spare Instance Spare v4 = 001, v6 = 010, v4v6 = 011 6 to n+4 Present if specified in the future Figure 4.16 The GTPv2 PDN Type information element carrying the requested PDN Type. Deploying IPv6 in 3GPP Networks IP Address Information Element In addition to the PDN Address Allocation information element, the IP Address information element is used in GTPv2 to carry around the user plane IPv4 or IPv6 address. The information element is currently (as for 3GPP Release-11) found included inside the PDN Connection Grouped Type information element used within the Forward Relocation Request and the Context Response messages. These messages are used during various handover and relocation procedures (over the S10-, S3- and S16-interfaces between MMEs and S4-SGSNs). Figure 4.17 shows the information element format. Typically, instance value 1 is used to indicate that the PDN Address Allocation information element contains an IPv6 address. The IPv6 address is a complete /128 IPv6 address, 