Installation and Operation Manual Chapter 6 Troubleshooting and Diagnostics
IPmux-11 Ver. 2.00 Monitoring Performance 6-3
Table 6-1. E1/T1 Statistics Alarm Description
LOS Number of seconds with Loss of Signal. A Loss of Signal indicates that there is either no signal arriving
from the adjacent E1/T1 device or no valid E1 voltage mask or no voltage alteration between positive
and negative amplitudes.
For E1 links, the LOS counter will increase by one for each second during which a consecutive
255 pulses have no pulse of negative or positive polarity.
For T1 links, the LOS counter will increase by one for each second during which a consecutive
192 pulses have no pulse of negative or positive polarity.
A LOS alarm is also indicated by the front panel E1/T1 SYNC LED (red). The green E1/T1 SYNC LED
indicates that the E1/T1 synchronization has been restored).
Recommendations:
Check the physical layer (connectors, cables, etc.)
LOF (Red) Number of seconds with Loss of Frame. A Loss of Frame indicates a second that IPmux-11 lost E1/T1
synch opposite its adjacent E1/T1 device.
In more detail, this is a period of 2.5 seconds for T1 or 100 msec for E1, during which an OOF (Out Of
Frame) error persisted and no AIS errors were detected.
For E1 links an OOF defect is declared when three consecutive frame alignment signals have been
received with an error.
For T1 links, an OOF defect is declared when the receiver detects two or more framing errors within a
three msec period for ESF signals and 0.75 msec for D4 signals, or two or more errors out of five or
fewer consecutive framing-bits.
A LOF alarm is also indicated by the front panel E1/T1 SYNC LED (red).
When the IPmux enters a red alarm condition, it sends an Yf bit (yellow alarm or RAI) towards the
adjacent E1/T1 device.
Recommendations:
Check all framing related parameters for E1/T1, and physical connections.
LCV Number of seconds with Line Code Violations. A Line Code Violation indicates an error on the pulse
structure, either a Bipolar Violation (BPV) or an Excessive Zeros (EXZ) error event.
BPV is the occurrence of a pulse with the same polarity as the previous pulse.
EXZ is the occurrence of a zero string greater than 15 for AMI or 7 for B8ZS.
For an E1 link, the LCV counter will increase by one, for each second during which a BPV or EXZ errors
have occurred.
For T1 links, the LCV counter will increase for each second during which two consecutive BPVs of the
same polarity are received.
Complies with ITU-TI.431, 0.161, G775 and G.821 standards.
Recommendations:
Check physical link for bad/loose connection, impedance matching (balanced or unbalanced) and noisy
environment.