Perle Systems IOLINK-PRO IOLINK-520 - Manual (Page 19)

Introduction
1.18 — IOLINK-PRO & 520 Reference Manual
WAN Topologies
The IOLINK router may be connected to other IOLINK routers in two configurations: Multipoint or Point-to-Point. The
WAN routing method used is set in the WAN Set-Up Menu under the Link Operation option.
Point-to-Point
In a Point-to-Point configuration, two IOLINK routers are connected together with one or two WAN links. Each
link may be set to an always active (unconditional) state or a backup/recovery (conditional) state.
A single link may be used for general traffic, and the second link may be used for disaster recovery or increased
throughput. The Bandwidth on Demand feature controls the conditional behavior of the second link in a Point-to-
Point configuration.
The Time of Day connect feature may be used in a Point-to-Point configuration to provide specific hours of access
or increased throughput.
Multipoint
In a Multipoint configuration, an IOLINK router is connected to more than one other IOLINK router. A
Multipoint configuration consists of three or more IOLINK routers connected together on the same wide area
network.
A dual-link IOLINK router that is connected to two different IOLINK routers (one on each link) is in a Multipoint
configuration.
The Time of Day connect feature may be used in a Multipoint configuration to provide specific hours of access.
Bandwidth On Demand
Each IOLINK router has the ability to automatically enable or disable a second link based on traffic activity, time of day, or
main link failure.
The Bandwidth on Demand feature allows you to use a second link only when required, thus saving the cost of having the
second link up and connected all of the time. The second link could be connected to an inexpensive dial-up line that is only
required when the main link fails or is exceeding a predefined traffic throughput level.
Bandwidth on Demand is accomplished by using the intelligence of the IOLINK router to measure the utilization of the
primary link. When it approaches saturation, Bandwidth on Demand will initialize and loadshare with a second stand-by link.
This will effectively increase the throughput of the IOLINK router, thereby alleviating the saturation and avoiding data loss.
The second link is then deactivated when traffic levels drop off to where the primary link can adequately handle the traffic
load once again.
When the stand-by link is activated, the IOLINK router raises the outgoing control signals. This control-signal transition is
then used to initiate autodial or auto call-setup procedures on the interface device. This autodial feature is standard on most
of the modems and terminal adapters on the market.
When the second link is deactivated, the IOLINK router lowers the outgoing control signals. This control-signal transition is
used to disconnect the call and bring down the link. The second link then remains in stand-by mode until the bridge/router
determines that the link must be used again.