t Service Centre (BM-SC), supports various MBMS user-specific services such as provisioning and delivery of mul- ticast traffic. In EPS a functional entity called MBMS Gateway exists at the edge between the core network and the BM-SC. In the case of EPS, the PGW is bypassed regarding Deploying IPv6 in 3GPP Networks 'Internal' content source Content Gn/Gp UTRAN BM-SC provider in Internet lu/Gb GERAN Figure 4.29 MBMS architecture for GPRS. Gateway eNodeB E-UTRAN Content BM-SC Provider Gateway SGi-mb UTRAN S4-SGSN Figure 4.30 MBMS architecture for EPS. the IP multicast traffic delivery. The BM-SC provides functions for MBMS user service provisioning and multicast traffic delivery. It may serve as an entry point for the content provider. The BM-SC is a functional entity, which must exist for each MBMS user service. The BM-SC consists of the following sub-functions: membership function session and transmission function proxy and transport function service announcement function security function content synchronization for MBMS in UTRAN content synchronization for MBMS in E-UTRAN for broadcast mode header compression in UTRAN; header compression is not supported in E-UTRAN as of 3GPP Release-11. Known IPv6 Issues and Anomalies This section describes and demonstrates some of the known anomalies and issues on early IPv6 deployments in GPRS and EPS networks. The issues discussed here show how little IPv6 in 3GPP Networks proper testing and serious deployment trials of IPv6 in a cellular environment there has been. Some of the documented cases are indeed SO trivial that they should not happen. We can partly also point at developers not fully understanding the difference between IPv4 and IPv6, specifically when it comes to link models and running IPv6 over arbitrary link technology. The documented issues in this section do not apply to all vendors and their products. The used 'sample' is more than one vendor, though. 4.9.1 IPv6 Neighbor Discovery Considerations IPv6 NDP is a complex protocol and getting it working properly 