Explicitly controlling channel allocation – Echelon LNS User Manual
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LNS Programmer's Guide
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As of LNS Turbo Edition, LNS does not support defining or modifying a
router as a learning router. If an application defines a router as a
learning router, or changes a routers class to lcaLearningRouter, the
LNS Object Server will automatically change the class to
lcaConfiguredRouter. See the next paragraph for a description of
configured routers, and the advantages they provide.
• A configured router forwards packets based on internal routing tables.
Configured routers have their routing tables in non-volatile memory. The
LNS Object Server configures and manages the routing tables based on
its knowledge of the network topology. In addition, a configured router
can be configured to selectively forward group-addressed messages when
it is known that all members of the group are on one side or the other of
the router. LNS manages the subnet and group forwarding tables in
configured routers automatically. This is the most efficient router
type to use, as it also allows the LNS Object Server to
automatically determine the channel each device is attached to,
supports physical loops, and reduces unnecessary network
traffic. Configured routers also support the use of redundant routers (see
the Explicitly Controlling Subnet Allocation section below), which provide
for redundant message paths.
In addition, you can define repeaters and bridges as permanent routers, meaning that
their types cannot be changed after they are installed. When a repeater or bridge router
is defined as permanent, the LNS Object Server knows that it will never be changed into
a configured router later, and it will allow the same subnet to exist on both sides of the
router. This is permitted by the router, since bridges and repeaters do not perform
forwarding based on subnet address.
If a router is defined as a non-permanent bridge or repeater, LNS will enforce the rule
that no subnet can appear on both sides of the router or bridge, even though the router
itself does not enforce this rule. This allows the LNS application to change the router
class later, without creating subnet conflicts. See the Explicitly Controlling Subnet
Allocation section below for more information on the role of subnets and the rules
regarding their allocation.
With the exception of learning routers, you can use LNS to configure a L
ON
W
ORKS
router
as any of the router types described in this section. The most efficient router type to use
is the configured router, as this allows the LNS Object Server to automatically determine
the channel to which each device is attached, supports physical loops, and reduces
unnecessary network traffic.
Explicitly Controlling Channel Allocation
Unless you are using the ad hoc or automatic installation scenario, you should explicitly
define the channels in your system, and specify those channels as devices and routers are
added to the system. When using the ad hoc installation scenario, you can omit the
channel definitions and allow LNS to create channels for you. When using an automated
installation scenario based on device discovery mechanism, LNS automatically creates
each AppDevice with the correct channel assignment. When explicitly defining a
channel, you must specify the channel’s media type, by transceiver ID. The LNS Object
Server includes the ConstTransceiverId constant, which includes enumerations for
each of the possible transceiver types you can use for this purpose.