14
User Guide
Metrobility T3/E3 15
Link Loss Indications
The following examples show the status of the LK LED under various link condi-
tions and describe when unframed all ones are generated. (Loopback is disabled in
these examples.)
Note:
An all-ones pattern indicates an alarm indication signal (AIS) for the E3 units
only. For T3 models, the all-ones pattern is simply transmitted to the remote device;
it does NOT indicate AIS.
Normal
The diagram below shows a typical configuration with good link status.
Remote
Device
Local
Device
Local T3/E3
Unit
Remote T3/E3
Unit
green LED
unlit LED
Coax
Coax
Fiber
LK
LK
LK
LK
Input Coaxial Link Loss
Loss of the copper input disables the BNC portʼs LK LED. It also forces the T3/E3
unit to generate unframed all ones (AIS for E3 only), which are transmitted out its fi-
ber port. For example, if the local unitʼs inbound coaxial cable breaks, it will transmit
all ones to the remote T3/E3 unit via the fiber cable. The remote unit then carries the
pattern forward via its coaxial cable to the remote device.
Input Fiber Link Loss
Loss of the fiber input is indicated by the fiber portʼs unlit LK LED. When the fiber
input is lost, an unframed all-ones pattern is transmitted from the coaxial port, as
shown in the following illustration.
Remote
Device
Local
Device
Local T3/E3
Unit
Remote T3/E3
Unit
green LED
unlit LED
Coax
Coax
Fiber
LK
LK
LK
LK
All Ones
All Ones
All Ones carried forward
