IPv6 Crash Course – Part 4

After I have dealt with the most essential IPv6 features for me in parts 1 to 3 (see here, here and here) this part focuses on the bits and pieces that have to fall in place in 3GPP GSM, UMTS and LTE networks to make it work.

First of all, mobile devices need to support IPv6. Some already do, such as Nokia devices running on Symbian/S60.In fact, Nokia supports IPv6 already since 2003 as shown in this IPv6 presentation from way back then…

Next, mobile devices need to be able to get an IPv6 address when they connect to the network. In GSM and UMTS, the PDP context activation request message contains the necessary parameters to request one. In LTE the default/dedicated bearer activation procedures provide similar capabilities. Dual stack devices can ask for an IPv4 and IPv6 address in one request. In addition, IPv6 requires a Router Solictiation message being sent from the UE and a Router Advertisement answer from the GGSN to finalize the IPv6 address creation. This is done over the established user data bearer. More details can be found below.

While in theory, user data is sent transparently back and forth between the mobile device and the gateway to the Internet (the GGSN or the PDN-GW), the base station should perform IP header compression (RoHC). In practice this will become even more important due to the significantly increased size of the IP header due to the 128 bit long IPv6 addresses, especially for voice calls.

At the gateway to the Internet, the GGSN (GSM/UMTS) or the PDN-GW (LTE) must be able to assign IPv6 addresses and provide firewall functionalities for IPv6 based communication. Further, the Home Subscriber Server (HSS) must be updated to support IPv6 parameters on a per user basis. And last, but by far not  least, are the IP Multimedia Subsystem (IMS) network nodes that have to handle IPv6 on the network layer but also inside SIP messages.

All of this has been in the standards for years so there's a fair chance we'll see it in the network sooner or later. Here's a couple of links for further information:

  • 3GPP TS 23.221 Rel 8, 'Architectural Requirements', Chapter 5.6 on IP addressing says that the mobile is free to change the host part of the IPv6 address at any time on it's own without updating the PS domain via a mechanism described in RFC 3041.
  • 3GPP TS 23.060 describes the PDP context activation procedure for IPv6 in Chapter in Figure 6.1 After the context is active, the UE sends a router solicitation message to the network (the GGSN) which then returns a Router Advertisement message. The information contain in this message is then used by the mobile to construct it's own IPv6 address.

Since I'm not an IPv6 guru, here's a question to all 3GPP IPv6 enthusiasts out there: Have I been missing an important point?