Espressif ESP32-S2 Programming Manual page 1336

Chapter 4. API Guides
– The channel discrepancy prevents any data exchange between the root node and the router during
that ESP-WIFI-MESH network's switch.
– In the ESP-WIFI-MESH network, the root node and intermediate parent nodes will request their
connected child nodes to stop transmissions until the channel switch takes place by setting the Chan-
nel Switch Mode field in the CSA element to 1.
– Frequent router triggered network channel switches can degrade the ESP-WIFI-MESH network'
s performance. Note that this can be caused by the ESP-WIFI-MESH network itself (e.g. due
to wireless medium contention with ESP-WIFI-MESH network). If this is the case, users should
disable the automatic channel switching on the router and use a specified channel instead.
• When there is a temporary channel discrepancy, the root node remains technically connected to the router.
– Disconnection occurs after the root node fails to receive any beacon frames or probe responses from
the router over a fixed number of router beacon intervals.
– Upon disconnection, the root node will automatically re-scan all channels for the presence of a router.
• If the root node is unable to receive any of the router's CSA beacon frames (e.g. due to short switch time given by the
– After the router switches channels, the root node will no longer be able to receive the router's
beacon frames and probe responses and result in a disconnection after a fixed number of beacon
intervals.
– The root node will re-scan all channels for the router after disconnection.
– The root node will maintain downstream connections throughout this process.
Note: Although ESP-WIFI-MESH network channel switching aims to move all nodes within the network to a new
operating channel, it should be recognized that a channel switch might not successfully move all nodes (e.g. due to
reasons such as node failures).
Channel and Router Switching Configuration
ESP-WIFI-MESH allows for autonomous channel switching to be enabled/disabled via configuration. Likewise,
autonomous router switching (i.e. when a root node autonomously connects to another router) can also be en-
abled/disabled by configuration. Autonomous channel switching and router switching is dependent on the following
configuration parameters and run-time conditions.
Allow Channel Switch: This parameter is set via the allow_channel_switch field of the
structure and permits an ESP-WIFI-MESH network to dynamically switch channels when set.
Preset Channel: An ESP-WIFI-MESH network can have a preset channel by setting the channel field of the
mesh_cfg_t structure to the desired channel number. If this field is unset, the allow_channel_switch
parameter is overridden such that channel switches are always permitted.
Allow Router Switch: This parameter is set via the allow_router_switch field of the
and permits an ESP-WIFI-MESH to dynamically switch to a different router when set.
Preset Router BSSID: An ESP-WIFI-MESH network can have a preset router by setting the bssid field
of the mesh_router_t
low_router_switch parameter is overridden such that router switches are always permitted.
Root Node Present: The presence of a root node will can also affect whether or a channel or router switch is
permitted.
The following table illustrates how the different combinations of parameters/conditions affect whether channel
switching and/or router switching is permitted. Note that X represents a "don't care"for the parameter.
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structure to the BSSID of the desired router.
1325
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mesh_cfg_t
mesh_router_t
If this field is unset, the al-
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