9.1 ALS Overview
The ALS mechanism controls the pulse of the laser of an optical module by detecting the Loss
of Signal (LOS) on an optical interface.
When ALS is disabled, if the fiber link is faulty, the optical interface is not disabled and the laser
of an optical module is enabled though data communication is interrupted. If the laser of an
optical module still sends pulses after data communication is interrupted, energy is wasted and
eyes of operators may be hurt.
When ALS is enabled, if the fiber link is faulty, the software automatically disables the laser of
an optical module from sending pulses on the optical interface after detecting the LOS on the
optical interface. When the faulty fiber link is recovered, the software detects that the LOS of
the optical interface is cleared. Then the software enables the laser to send pulses. The ALS
mechanism protects operators against laser injury and saves energy.
9.2 ALS Features Supported by the S5700
This section describes the ALS features supported by the S5700.
Applicable Environment of ALS
l
The switches are connected through fibers.
When switches are connected through fibers, the ALS function can be enabled on interfaces
of switches to protect users against laser radiation to eyes, as shown in
Figure 9-1
Connecting switches through fibers
SwitchA
SwitchB
TX
RX
RX
TX
l
The switch and the optical network terminal (ONT) are connected through fibers.
In the application of fiber to the home (FTTH), if ONT users perform improper operations
on the fiber because of lack of knowledge about radiation or children touch the fiber, the
radiation of the laser harms eyes. To solve this problem, you can enable the ALS function
on the switch to protect safety of users.
Figure 9-2
Connecting the switch and ONT through the fiber
TX
TX
RX
RX
Switch
ONT
Quidway S5700 Series Ethernet Switches
Configuration Guide - Device Management
9 ALS Configuration
Issue 01 (2011-07-15)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
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