805U-E Wireless Ethernet
User Manual
Man_805U-E Rev 1.5
Page 34
For example, consider this network with a redundant wireless link. If the Spanning Tree
Algorithm function is enabled, one of the two wireless 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 redundant 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 handles the majority of traffic in the network. As a
low bandwidth radio device, the 805U-E is configured with a Bridge Priority of (255) by
default. The intention is reduce traffic that the 805U-E must handle, by placing it at the
branch level in the network tree. As a branch, the 805U-E 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
Routing Rules
When a 905U-E receives an IP frame that is destined for an IP address on a different
network, it checks if the network address matches the network address of one of its own
interfaces (i.e. hard wired Ethernet, or wireless Ethernet, or PPP) and forwards the frame
appropriately. However, if the IP network address does not match any of its interfaces, the
905U-E will forward the frame to its default gateway. In this case it is assumed that the
default gateway has a valid route to the destination.
In some cases it is not practical to have just one default gateway (i.e. routed wireless
networks with more than two 905U-E routers). If more than one “next-hop router” is
required, the 905U-E allows for up to 30 routing rules to be configured. A routing rule
specifies a destination network (or host) IP address and the corresponding next-hop router
that messages for the specified destination will be forwarded to. It is assumed that the next-
Client
Bridge
Access Point
Bridge
Access Point
Bridge
Client
Bridge
