Campbell CR1000, Руководство оператора

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Section 8. Operation
• neighbor
•
neighbor-filters
• hello
• hello-exchange
•
hello-message
• hello-request
• CVI
•
beacon
To form a network, nodes must establish links with neighbors (neighbors are
adjacent nodes). Links are established through a process called discovery.
Discovery occurs when nodes exchange hellos. A hello-exchange occurs during a
hello-message between two nodes.
8.5.3.1 Hello-Message
A hello-message is a two-way exchange between nodes to negotiate a neighbor
link. A hello-message is sent out in response to one or both of either a beacon or
a hello-request.
8.5.3.2 Beacon
A beacon is a one-way broadcast sent by a node at a specified interval telling all
nodes within hearing that a hello-message can be sent. If a node wishes to
establish itself as a neighbor to the beaconing node, it will then send a hello-
message to the beaconing node. Nodes already established as neighbors will not
respond to a beacon.
8.5.3.3 Hello-Request
A hello-request is a one-way broadcast. All nodes hearing a hello-request
(existing and potential neighbors) will issue a hello-message to negotiate or re-
negotiate a neighbor relationship with the broadcasting node.
8.5.3.4 Neighbor Lists
PakBus devices in a network can be configured with a neighbor list. The CR1000
sends out a hello-message to each node in the list whose
CVI
(p. 511)
has expired at
a random interval
1
. If a node responds, a hello-message is exchanged and the node
becomes a neighbor.
Neighbor filters dictate which nodes are neighbors and force packets to take
routes specified by the network administrator. LoggerNet, which is a PakBus
node, derives its neighbor filter from link information in the LoggerNet Setup
device map.
1
Interval is a random number of seconds between the interval and two times the interval, where the
interval is the CVI (if non-zero) or 300 seconds if the CVI setting is set to zero.
8.5.3.5 Adjusting Links
PakBusGraph , a client of LoggerNet , is particularly useful when testing and
adjusting PakBus routes. Paths established by way of beaconing may be
redundant and vary in reliability. Redundant paths can provide backup links in the
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