Roaming Design

WLAN roaming addresses the following issues:

• Retains users' IP addresses. After roaming, users can still access the initially associated network and continue its services.
• Avoids packet loss or service interruption caused by long-term authentication.

WLAN roaming is classified into the following types based on the STA roaming scope:

• Intra-WAC roaming
• Inter-WAC roaming at Layer 2 or Layer 3

In actual deployment, intra-WAC roaming is recommended. Inter-WAC roaming can be avoided through proper AP group management. For services with high latency requirements, such as automated guided vehicles (AGVs), in warehouses and factories, it is recommended that a separate SSID or VLAN be planned to implement Layer 2 roaming within the WAC.

In the native WAC scenario, if the number of STAs is greater than or equal to 40,000, a maximum of four native WACs can be deployed in each mobility group; if the number of STAs is less than 40,000, a maximum of 16 native WACs can be deployed in each mobility group.

In addition to the preceding basic roaming functions, Huawei WLAN supports the fast roaming function, including pairwise master key (PMK) fast roaming and 802.11r fast roaming. This function further reduces the handoff delay between APs. Table 3-8 shows the handover delay of STAs in different roaming modes.

802.11r fast roaming supports an enhanced roaming mechanism based on device-pipe synergy when working with Huawei terminals. This mechanism helps further reduce the roaming handover delay and packet loss rate. Therefore, you are advised to enable the machanism when enabling 802.11r fast roaming.