ProSoft Technology RLX2-IHW-E User Manual page 104

RLX2-IHx Series ♦ 802.11a, b, g, n
Industrial Hotspots
Rapid Spanning Tree Functionality
Rapid Spanning Tree Protocol (RSTP) is an advanced networking function that shuts off
ports as necessary to prevent data packet loops when more than one network path is
available. If loops exist in an Ethernet network, the devices can circulate packets
endlessly, consuming all the bandwidth and making the network unusable.
RSTP allows the radios to create truly redundant connections between any two points in
the network, but use only one path at a time. The radios detect the redundant paths and
use only one primary connection for communications. If the primary connection fails, the
radios quickly change to the secondary connection to a state to forward packets,
allowing the network to adapt itself to handle problems without requiring your
intervention.
RTSP uses active communications between network devices to quickly propagate
changes and transitions in the network. Because RTSP is an IEEE standard, RLX2-IHx
series radios work in conjunction with wired Ethernet switches to form a redundant
network.
Each RSTP device (RLX2-IHx series radio or Ethernet switch) communicates with other
RSTP devices in the network using packets called Bridge Protocol Data Units (BPDUs).
Each device sends BPDUs out each of the devices ports. In a wired switch, this is from
each of the Ethernet ports. In an RLX2-IHx series Radio, this is from both the Ethernet
port and each wireless link. BPDUs allow each RSTP device in the network to make
sure that the proper connections still exist.
The Port Status dialog box shows a list of all ports and their state. In the top part of the
radio web interface, click P
this example, the RLX2-IHx series radio has 4 RSTP "ports":

Ethernet port (1)

A port for its parent connection (2)

A port for each of its two child connections (11 and 12)
BPDUs are sent out the port at a rate called the Hello Time set on the A
N S
ETWORK ETTINGS
a radio (or any other RSTP device) does not get a BPDU from a device for a time period
equal to two Hello Times, the radio assumes the RSTP device is no longer available.
The radio can then open a redundant path if one is available. This process is much like
the STP process. If other devices on the network are not operating in Rapid Spanning
Tree mode, the radio reverts to normal Spanning Tree operation on the ports connected
to those devices.
RSTP provides a performance enhancement over STP.
ProSoft Technology, Inc.
S . See Viewing the Radio Port Status (page 62). In
ORT TATUS
tab. The accepted standard value for this parameter is 2 seconds. If
Configuring a Radio - Detailed Configuration
DVANCED
User Manual
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