STP Scenarios Supported by a WDS Network
A WDS network supports only transparent transmission of STP packets. An STP-enabled AP does not forward STP packets to the wireless side. STP takes effect only on the AP's wired side.
When deploying a WDS network, avoid network loops. In WDS networking, STP applies only to scenarios where the WDS network forms a single loop with the wired network. The WDS network supports the following three STP scenarios:
- WDS links form a single loop with wired links. STP is enabled on non-AP network elements (NEs) on the loop but not enabled on NEs connected to the WDS network that are not involved in the loop. In this case, STP takes effect and breaks the loop.
As shown in the Figure 1 and Figure 2, the switch forms a single loop with WDS links. To break the loop, enable STP on the switch and ensure that STP is not enabled on GE0/0/1 connecting the AC to the root node.
- The WDS network connects to an AP with dual network ports. A loop exists on the AP's wired-side interfaces and the wired-side interfaces are not bound to an Eth-trunk interface. To prevent transparent forwarding of STA packets to the wireless side, enable STP on the AP.
In the Figure 3, the AC, SwitchA, SwitchB, and root node form a loop (loop 1), and SwitchC, SwitchD, and the leaf node form a loop (loop 2). If STP packets are transparently transmitted over WDS links, STP on loop 1 incorrectly includes SwitchC and SwitchD on loop 2 into its calculation.
To prevent calculation errors, enable STP on the root node and leaf node so that STP packets from loop 1 and loop 2 will not be transparently forwarded to the wireless side. The root node implements STP calculation of loop 1 and blocks wired-side interfaces based on the calculation results. The leaf node implements STP calculation of loop 2 and blocks wired-side interfaces based on the calculation results.
