User's Manual

RLX2 Series ♦ 802.11a, b, g, n Detailed Radio Configuration / Diagnostics
Industrial Hotspots User Manual
6.2.3 Rapid Spanning Tree Functionality
The software’s built-in Rapid Spanning Tree (RSTP) functionality enables the
setup of full redundancy between radios or other devices. Spanning Tree shuts
off ports as necessary to prevent loops. If loops are created in an Ethernet
network, packets can be circulated endlessly, consuming all the bandwidth and
making the network unusable.
Important: All radios in a network must have the same Spanning Tree configuration (enabled or
disabled.) Radios will not link if some of them have Spanning Tree enabled while others do not.
RSTP allows users to create truly redundant connections between any two points
in the network. The radios detect the redundant paths and keep one connection
alive for communications. If the primary connection fails for any reason, the
secondary connection is quickly transitioned to a state to forward packets,
allowing the network to adapt itself to handle problems without customer
intervention.
RSTP uses active communications between network devices to propagate
changes in the network and to cause transitions to occur much more quickly.
Because RSTP is an IEEE standard, RLX2 radios work in conjunction with wired
Ethernet switches to form a redundant network. Spanning Tree details are
described in the IEEE 802.1D series of specifications.
Each RSTP device (RLX2 Radio or Ethernet switch) communicates with other
RSTP devices in the network via packets called Bridge Protocol Data Units
(BPDUs). BPDUs are sent out each of the devices ports. In a wired switch this
would be from each of the Ethernet ports. In an RLX2 Radio, in addition to the
Ethernet port, each wireless link is considered a port. These BPDUs are the
communications means to allow each RSTP device in the network to make sure
that the proper connections still exist.
ProSoft Technology, Inc. Page 67 of 161
November 29, 2012