A router is not included in a typical RFID system. A typical RFID system consists of three components: RFID tag, RFID reader, and information processing platform. The RFID tag is attached to the object to be identified, the RFID reader communicates with the tag and reads its information, and the information processing platform processes and stores the data collected by the reader.
References: https://support.huawei.com/enterprise/en/doc/EDOC1100058940/8a8f1c9b/rfid

In Huawei's smart roaming solution, the WAC can discover and maintain neighboring AP entries of STAs by using two methods: passive listening and active scanning. Passive listening means that the AP listens to the Probe frames sent by STAs and reports them to the WAC. Active scanning means that the AP periodically and proactively scans neighboring APs of STAs and reports them to the WAC.
References: https://support.huawei.com/enterprise/en/doc/EDOC1100058940/8a8f1c9b/smart-roaming

When a STA roams from AP1 to AP2 at Layer 2, AP2 notifies its neighbors of the MAC address learned from this STA. The MAC address is not encapsulated in a tunnel and sent to AP1 for forwarding. Instead, AP1 deletes the MAC address entry of the STA and releases the IP address lease.
References: https://support.huawei.com/enterprise/en/doc/EDOC1100058940/8a8f1c9b/layer-2-roaming