User Manual

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Understanding Industrial WLAN – IEEE 802.11
Wireless Bridge mode can also connect wireless clients to another SSID, as shown below, so it can be used
in environments where APs cannot be wired.
Figure: Bridge Mode for Extra APs
Mesh Technologies
Mesh technologies are generally considered to be wireless communication systems that are interconnected to
each other. However, there are two distinctive ways to build up a so called mesh network: wireless distribution
systems (WDS) and mesh routing. Both of these methods create Layer 2 connections to one or more bridges /
mesh routers to allow data to be passed between them.
WDS differs from mesh routing in many ways. Generally WDS has the nature of a more static network
configuration without significant demand for redundancy. That is, a wireless bridge is configured to point to the
adjacent bridge with a predefined MAC address. So when a bridge fails and while there is no adjacent bridge is
configure to serve as a backup path, the link will be lost.
A wireless mesh routing link, on the other hand, can provide greater redundancy because it can create a
redundant path in the event of node failure. In other words, the mesh router automatically detects a new node
when the original node fails and dynamically determines the best path.
While a WDS is more of a standard and a mesh routing link is more of a proprietary standard, they are being
adopted in accordance with users’ needs. A WDS is often employed in a hierarchical network topology
for bridges that can not prevent broadcast storms. As a result, a WDS is often configured in spanning tree
topologies. A bridge loop is often avoided to prevent a broadcast storm. However, there are software solutions
which utilize Spanning Tree Algorithms (STA) to compute the best path between two nodes while putting all
other paths in blocking mode. This realizes communication redundancy in a WDS but it can be time consuming
to create a workable bridge loop. So a WDS is often adopted in a small network that requires manual
configuration for each node. Once the connection is established, it is not easily interrupted.
Mesh routing on the other hand is often adopted in systems that require higher redundancy. It often needs few
manual configurations for each node and provides greater expandability when more nodes are to be added in
the future. In summary, redundancy is the primary concern when choosing mesh routing links. It is also more
of a suitable choice when the connections are subjected to constant disruptions, for example, by passing by
buses.
Figure: Wireless
Bridge Mode