AutoWDS – wireless integration of APs via P2P connections

In a centrally managed WLAN network, access points (APs) are typically connected to the WLAN controller (WLC) via the LAN. The LAN connections simultaneously determine the topology of the managed network. Network extension by means of additional APs is restricted to the reach of the hard-wired network architecture and requires the extension of the corresponding infrastructure.

By means of AutoWDS, you have the option of extending a WLAN by means of point-to-point (P2P) connections for the cost-effective and fast installation of highly scalable networks. "AutoWDS" stands for "automatic wireless distribution system". This feature enables you to create a radio network from several APs, which are interconnected via wireless only: a logical connection is all you need. Potential applications include the seamless connection of smaller properties or even entire districts to the Internet, or the establishment of a company network where connections via LAN are impracticable.

Important: AutoWDS is not supported anymore as of LCOS 10.70. The functionality still remeins intact in LANCOM devices (except in 18xx series routers) and therefore still can be used for existing installations. However LANCOM Systems will not provide any support regarding the configuration and troubleshooting of an AutoWDS scenario.

In the simplest case, all you need is a WLC connected via LAN to an AutoWDS-enabled AP. The AP supports the managed network and at the same time acts as an "anchor AP". Using this anchor AP, unassociated AutoWDS-enabled APs connect to the WLC, which transmits a configuration to them by means of CAPWAP. After obtaining the configuration and being incorporated into the managed WLAN, the individual APs use P2P links to forward user data, to communicate with one another, and to support the topology. Additional APs that join later are able to use the associated APs as their anchor APs. In this manner, several APs can be chained together to establish meshed networks, which can optionally feature redundant connections via RSTP. From the perspective of an unassociated AP, associated APs are master APs. From the perspective of the master AP, unassociated APs are slave APs.

Figure 1. Phase 1 – unassociated AP in building B seeks AutoWDS base network and finds anchor AP in building A

Figure 2. Phase 2 – unassociated AP in building B finds WLC and retrieves AP configuration via CAPWAP

Figure 3. Phase 3 – unassociated AP in building B joins the managed WLAN. Unassociated AP in building C seeks AutoWDS base network and finds anchor AP in building B

Precise information about the integration process and the operating modes for topology management can be found in the following sections, which describe how AutoWDS functions.

Important: AutoWDS is suitable for static infrastructure only, not for mobile APs. If an AP should move out of range of its P2P partner and lose the connection to the network, there is a temporary downtime and a subsequent reconfiguration. However, the roaming of WLAN clients between individual AutoWDS APs is no different than the roaming between conventional APs.

Important: AutoWDS does not support the network separation of SSIDs to VLANs by means of a static configuration or a dynamic VLAN assignment via RADIUS. Implementing a network separation of SSIDs requires these to be separated by means of layer-3 tunnels.

Important: The DFS processing by an AP in 5-GHz operation is unaffected by AutoWDS and has a higher priority. DFS radar recognition may cause the AP to suddenly change the channel during operation. It can even completely deactivate the WLAN for a period if radar recognition is running on different channels and the available frequencies drop out. The impacted AP can cause interference to the entire AutoWDS group, and may not be able to deploy any SSIDs for some time. Within buildings you have the option of counteracting interference by enabling the indoor mode.

Note:

If you operate AutoWDS on a device with a single physical WLAN interface, its data rate will be reduced to just a third, since the device must send incoming/outgoing data multiple times: To the WLAN clients, to a master AP and, if applicable, to a slave AP. This effect is mitigated by operating only devices that have multiple WLAN physical interfaces and using these to divide up the data traffic. You do this by reserving one physical WLAN interface for connecting the APs and one physical WLAN interface for connecting the clients.

MultiHop on the same WLAN interface can be enabled in the AutoWDS profile configuration, if necessary. This is disabled by default due to the associated loss of performance.