How is wireless roaming defined, and how many ways?

How is wireless roaming defined, and how many ways?

Wireless roaming is generally defined as wireless terminal users can move freely between the same SSID, and keep the original IP address and corresponding permissions unchanged. Roaming can be divided into two-layer roaming and three-layer roaming. There is also a special type of roaming, which is roaming between APs managed by different ACs, that is, roaming domains.