e a certain level of quality and the 2nd a certain bandwidth guaranteed, the process of im- plementation will follow typical steps. The MS and the network negotiate and agree QoS level during the PDP-context activation. However, based on the availability of radio resources, it may also be re-negotiated later during the session. We can illustrate these steps as follows: The MS sends an active PDP context message to the SGSN containing, e.g. the access point name and a number of other parameters including a QoS profile. The SGSN verifies the request with the HLR based on the user's subscription pro- file. If there is contradiction, the QoS request may be rejected. Otherwise, the SGSN will issue a DNS query to identify the IP address of the GGSN associated with the requested access point. The SGSN then issues a create PDP context request to the GGSN with the re- negotiated QoS profile. The GGSN may accept or decline this request. The GGSN replies with its acceptance of the PDP context request to the SGSN and the SGSN in turn to the MS. In the IP backbone, dedicated traffic for example, will make use of the Type of Service (ToS) field in the IPv4 or Ipv6 header to classify traffic. Then the GGSN and SGSN map the QoS profile requested in the PDP context activation message to dedicated code points. The UMTS Network and Radio Access Technology We can also map dedicated classes to ATM Permanent Virtual Circuits (PVCs) to pro- vide guaranteed QoS. However, this is still undergoing consolidation in the standardiza- tion bodies, e.g. IETF. We may also map dedicated classes to MPLS labels, where the latter defines a protocol for encapsulating IP packets. MPLS, which has awareness of routing devices, uses a four-byte label added to the original packets. Thus, MPLS aims to simplify routing de- cisions by allowing packets to go along specific routes based on QoS parameters among others. 3.2.5.7 Implementing lpv6 The introduction of IP terminals in 3G will dramatically increase the need for new IP addresses. Thus, we turn to IPv