e dedicated bearer had already stopped, and hence the bearer was deactivated. The dedicated bearers can be deactivated for various reasons by the UE, the MME, and the PGW. The EPS system also has what is called multiple PDN support. Practically, this means that a UE can be connected to multiple IP networks at the same time. Hence, it has multiple IP addresses. Figure 2.16 describes the UE requested PDN Connectivity procedure. The idea is the same as in GPRS with multiple Primary PDP Contexts. 1. PDN Connectivity Request is sent by the UE to the MME via the eNodeB. The PDN Connectivity Request indicates what kind of connectivity (IPv4, IPv6, or both) is requested to which network. 2. Create Session Request message is created by the MME and sent to the SGW. The SGW creates an entry for this new bearer in its EPS Bearer table, and forwards the message to the PGW. The PGW also generates a new entry for in its EPS Bearer table and allocates the IP address(es) for the bearer. 3. Create Session Response is created by the PGW including the needed configuration information such as the IP address, PCO, and QoS information. The message is sent to the SGW, which forwards it to the MME. 4. Bearer Setup Request/PDN Connectivity Accept message is sent to the eNodeB. The Bearer Setup Request indicates to the eNodeB to start the radio bearer negotiation with the UE. The PDN Connectivity Accept is a response to the UE to the PDN Connectivity Request. The PDN Connectivity Accept is sent within the Bearer Setup Request message. Basics of the 3GPP Technologies eNodeB 1. PDN Connectivity Request 2. Create Session Request 3. Create Session Response 4. Bearer Setup Request 5. RRC Connection Reconfiguration 6. Bearer Setup Response 7. PDN Connectivity Complete 8. Bearer Modification 9. IP traffic Figure 2.16 UE requested PDN connectivity. 5. RRC Connection Reconfiguration message exchange sets up the radio bearers between the UE and the eNodeB. The PDN Connectivity Accept message is delivered to the UE at this point. 6. Bearer Setup Resp