© Microhard Systems Inc. Confidential 51
3.0 Mesh Configuration
3.2.7 Routing
For Mesh Networking to be an effective networking topology, routing functions must be performed to
discover paths within the network to each destination, to ensure the best path is chosen. All units in a
Mesh Network, including remotes, can be configured to provide routing capabilities by setting register
S223.
S223 = 0 - Routing Disabled
S223 = 1 - Routing Enabled
All traffic in a Mesh system is either broadcast, where data is sent to everyone; or unicast, where data is
sent to a specific destination. Anytime there is no direct line of sight with a primary coordinator, addi-
tional coordinators can be added to extend the network. If data is transmitted to a unicast destination,
the modems will use a Microhard routing protocol to find a route by initiating route discovery. At this
point routing is required to provide route information and load balancing of the network traffic. Routing is
a key element in Mesh network design that can have a profound impact on overall system performance.
The diagram below shows a sample Mesh Network comprised of a Primary Coordinator, a Secondary
Coordinator and 11 remotes. Routing has been enabled on the Secondary Coordinator and two of the
remotes to provide comprehensive routing capabilities. It is always a good idea to assign routing opera-
tion to more than one unit to provide redundancy, and to provide alternate paths for routed data to
travel, essentially sharing the load of the network. Generally remotes sitting on the edge of the network
are not required to perform routing.
As traffic flows through and around a network, routing tables in each unit will be populated using
route discovery and routing requests as required routes are discovered. Eventually the entire network is
converged, meaning a path to all units are mapped, until something changes - a unit moves, a unit is
added, or a unit is removed from the system. When this happens, the routing table(s) must be updated.
P.C.
RT
S.C
Primary
Coordinator
Routing
Enabled
Secondary
Coordinator
Drawing 3-7: Mesh Network w/Routing
RT
RT
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