Campbell CR800 Dokumentacja Pobierz pdf (Strona 300)

Section 14. PakBus Networking

14-16

RoutingTable(3) – PakBus address of the destination PakBus device

(LoggerNet in this example)

RoutingTable(4) – Hop metric (expected response time in milliseconds) of the

destination node. The Standby Mode of RF401s with an RF PakBus protocol

affects the hop metric.

A network’s distributed routing system is fundamentally driven by routers

learning who their neighbors are, then sharing that information with the other

routers in the network so each router can choose the best routes to all nodes.

To this end, it is the goal of a router to know the neighbor lists of every other

router in the network. An exception to this is the branch router.

14.3.7 Branch Routers and Central Routers

A branch router only strives to know the neighbor lists of (1) the Central

Routers, (2) the routers between itself and the central routers, and (3) the

routers that are outward from itself in the network. Central routers know the

entire network. The fact that branch routers have the central routers in their

routing tables enables them to access every node in the network.

Making a router into a branch router reduces the size of its routing table. For

example, RF401s are candidates for branch router when configured as stand-

alone routers in a network having many routers and/or excessive

communications traffic. In general, branch routers should be viewed as a way

to reduce RF traffic; however, if the number of network routers is greater than

about 10, then configuring RF401 series stand-alone routers as branch routers

becomes necessary due to limited radio memory resources. Central routers

appropriately chosen for a given network (see example below) can reduce to

approximately half the number of nodes the branch routers must keep track of

in their routing tables.

Indications that the network routing information exceeds the memory

capability of your stand-alone router(s) include: in a beaconing network, a

stand-alone router doesn’t have routes to all the nodes in the network as it

should; and LoggerNet is unable to connect to some node(s) that route through

stand-alone router(s). You can see a stand-alone router’s Routes (routing

table) in PakBus Graph by right-clicking on that node and selecting Show

Settings.

To divide a network into branches and configure branch routers it is necessary

to designate one or more routers in the network as central router(s). The

remaining routers in the network must all be configured as branch routers

which is accomplished indirectly by listing the central router PBAs in all the

branch routers’ Central Router fields.

Rules of branch routing:

1. Central routers are contiguous (no branch router may separate the central

routers)

2. The central routers extend far enough from LoggerNet to isolate the

branches

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