Westermo RM-80 - Manual (Page 29)

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3.10 Spanning Tree Algorithm / Redundancy
The “Spanning Tree Algorithm” function was introduced to handle network loops and
provide redundant paths in networks. The Spanning Tree Algorithm can be configured,
however the factory default setting is “disabled”.
For example, consider this
network with a redundant
wireless link. If the Spanning
Tree Algorithm function is
enabled, one of the two wire-
less links will be disabled
– that is, all wireless data will
be transferred by one link
only. If the active link fails, the
other link will automatically
start transferring the wireless
data.
The Spanning Tree Algorithm
implemented is IEEE 802.1d
compatible. The algorithm forms a loop-free network by blocking traffic between redun-
dant links in the network. These blocked links are placed in a standby condition, and may
be automatically enabled to repair the network if another link is lost. The Spanning Tree
Algorithm maintains a single path between all nodes in a network, by forming a tree-like
structure. The Bridge Priority determines where the node sits in the tree. A Bridge with
the lowest priority configured (0) will become the root node in the network, and will
direct traffic between each of its branches. The root node is typically the unit that han-
dles the majority of traffic in the network. As a low bandwidth radio device, the RM-80 is
configured with a Bridge Priority of (255) by default. The intention is reduce traffic that
the RM-80 must handle, by placing it at the branch level in the network tree. As a branch,
the RM-80 needs only pass traffic to devices that are its “leaves”.
There is some overhead in maintaining a network utilizing the Spanning Tree Algorithm.
Users wishing to increase their throughput, at the expense of redundancy should disable
Spanning Tree.
3.11 Wireless Message Filtering
When configured as a Bridge, the RM-80 will transmit all broadcast messages appear-
ing at its wired Ethernet port. When the RM-80 is configured as a Router, this does not
occur.
In many cases, the intended recipient of the broadcast traffic does not lie at the opposite
end of a proposed radio link. Reducing unnecessary broadcast traffic sent over the radio
link, will increase available bandwidth for data. The RM-80 has a filtering feature to help
reduce unnecessary wireless transmissions and enhance security.
The RM-80 may be configured to reject or accept messages to and from certain
Addresses. To accept wireless messages from particular devices a “Whitelist” of
Addresses must be made. Alternatively to reject messages from particular devices, a
“Blacklist” of Addresses must be made. Filtering applies only to messages appearing at the
wired Ethernet port of the configured RM-80.
6XXZhhEd^ci7g^Y\Z 8a^Zci7g^Y\Z
6XXZhhEd^ci7g^Y\Z 8a^Zci7g^Y\Z