Examples of techniques for Association Identifier (AID) assignment are disclosed. In an example, a controller managing an AP may allocate a set of numbers for AID assignment to clients connecting to VAPs in a multiple BSSID set of the AP. The controller may configure the AP to assign AIDS to non-Multi-Link (non-ML) clients from a first subset of the set based on a first monotonic sequence and assign AIDS to ML clients from a second subset of the set based on a second monotonic sequence. The AP may receive an association request from a client to associate with a VAP of the multiple BSSID set, determine whether Multi-Link operation (MLO) is enabled for the client, and in response to determining that MLO is disabled for the client device, assign a first AID to the client from the first subset based on the first monotonic sequence.