User's Manual

Rapid Link Shutdown
79
Horizon Compact Plus Release 1.0.1 Wireless Ethernet Product User Manual – Volume 2
A “hard failure” mode triggers on a percentage of erred packets on a link. This mode is
applicable to link outages or severely degraded data transfer.
o The default value of error threshold is a loss of 50% of Rx Blocks (packets) over a
default sample time of 50 mS. The sample time and error threshold are user-
configurable.
o Advanced Mode provides support for a combined “hard”/”soft” failure mode
 Fast RLS switch for “hard” failure (severe degradation or link outage)
 Longer sample time and RLS switch for “soft” failure (high error rate)
Increased flexibility in setting a larger differential for “break vs. make” error values
Addition of a Receive Signal Level “RSL” threshold monitor to be optionally used in “make”
criteria for link startup
14.2 RLS Configuration – Port Groups
When RLS is enabled there are two options available for determining when RLS should be invoked to
shut down the Ethernet ports. These are the basic and advanced modes. The port group configuration
determines what port, or ports, the system will monitor and apply the failure algorithms to before a port
shutdown takes place. Note that any port that is part of a port group cannot be used for management,
regardless of the status of RLS (enabled or not).
14.2.1 Basic Mode
In basic mode, the user can configure the modem Block error rate thresholds under which RLS will be
invoked and the Ethernet ports disabled. The user can also set the thresholds for which RLS will be
revoked and the Ethernet ports brought back to service. Complete link outages due to loss of Ethernet
connectivity, loss of RF path, hardware failure, or power failure will trigger an RLS event and the
modem’s Ethernet ports will be shut down until the outage is repaired.
The basic mode relies on the follow situations occurring:
“Soft” failure. This mode monitors the link for data errors either as a steady state error rate or bursts
of data errors.
a. The RLS signal degrade settings correspond to “soft” failure mode.
b. Minor modem block errors can be corrected by the modem. This correction is invisible
to the user and is not traffic affecting. The Rx Blocks Error counter indicates
uncorrectable errors in the modem block stream over the air. Modem blocks may, or
may not, contsain user/payload data. The counter is a true representation ov over-the-
air data performance, even when there is no user data present.
c. The sample time is user configurable
d. An RLS signal degrade threshold setting in percentage is available to allow shorter
sampling times should errors occur on a frequent basis.
14.2.2 Advanced Mode
The advanced mode relies on any of the following situations occurring:
1. “Hard” failure. This mode invokes RLS when the link has deteriorated to a point of a massive
amount of data errors being received over the link.
a. A link outage will trigger an immediate RLS condition.
b. The RLS signal fault parameters correspond to “hard” failure mode.
c. The user-configurable error rates vary from 5% to 95%.
d. The user-configurable sample time ranges from 5 mS to 1000 mS.