# A Method for 5G-ICN Seamless Mobility Support Based on Router Buffered Data
## 3 Bdmm
### Architecture Overview  
Operators can use ICN as DN and extend the 5G core network to provide session mobility support [7]. The advantage of ICN as a DN integrated with 5G is that ICN introduces name-based identities which are location-independent, and can handle host mobility very effectively by applying the application-bound identifier and name resolution split principle. ICN also allows content to be independently replicated at network nodes or propagated through ICN routers, thereby bringing benefits to high-bandwidth/low-latency applications (such as AR/VR). Referring to [7], our proposed seamless mobility support method adopts 5G-ICN architecture, which uses SEANet [35] in the DN and can achieve coexistence with existing IP networks. A central feature of our approach is the use of SEANet to support session mobility. As shown in Figure 1, the UPF sinks to the edge of the network and is deployed in a distributed manner close to the base station (BS). In dense base station deployment scenarios, one UPF can connect multiple base stations. When the UE switches to the base station under the same UPF, the network address does not change. We define the above handover as a non-cross-UPF handover (as shown in Figure 1, the UE switches from BS2 to BS1). When the UE switches between base stations under different UPFs, the network address changes. We define the above handover as a cross-UPF handover (as shown in Figure 1, the UE switches from BS2 to BS3). Figure 1: BDMM’s architecture and handover process. Following the basic principle of identity-location separation in ICN, each network entity is assigned an Entity-ID (EID) as an identifier (or name) and a Network Address (NA) as a locator. Entities such as content, devices, and services are considered network entities. In order to ensure compatibility with existing IP networks, the IP address is used as NA. The Name Resolution System (NRS) maintains a mapping between identifiers and locators. UE and ICN routers in the DN support identity-based ICN packet forwarding, and other network devices (BS, UPF, etc.) support IP packet forwarding. Considering the scenario where the UE requests the Content Server, the request packet has the same format as the data packet, and both need to carry the source EID (UE's/Content Server's identifier), destination EID (Content Server's/UE's identifier), source network address (UE's/Content Server's network address) and destination network address (Content Server's/UE's network address). We collectively refer to request packets and data packets as packets. In order to implement the dynamic buffer resource allocation strategy, the data packet also needs to carry the service type that identifies its business type. Referring to MobilityFirst [36], the function of the ICN router, which alters the destination address of packets based on the identification (destination EID), is identified as a late-binding function. We designate the ICN router executing late-binding processing as a late-binding node (LBN). The ICN router can locate the valid network address of the mobile entity in the Name Resolution System (NRS) using the identifier of the mobile entity. In order to implement packet buffering and packet redirection, each ICN router needs to provide a buffer and to maintain a Mobile Entity State Table (MEST), which consists of a set of Mobile Entity State Table Entries (MESTEs). Each MESTE includes the EID and the New NA (the latest network address of the EID or the default value). Figure 2 describes the process of ICN router forwarding packets. After receiving the packet, the ICN router first queries MEST based on the destination EID carried in the packet. If there is a matching MESTE and the New NA in the table entry is not the default value, the packet will be late-binding, that is, the destination network address in the packet will be replaced with the corresponding NA in the MESTE, and then the FIB will be matched for forwarding. If a matching MESTE exists and New NA in the table entry is the default, the ICN router will buffer the packet.