Chapter 3. 9500 MXC Nodes
Vol. II-3-86 Alcatel-Lucent
• A silent transmitter switch
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is initiated when both far-end receivers are in
path-fail alarm, and the link has been wrapped for not less than 5 seconds.
• If the link failure is due to a path fade, the silent transmitter command from
the far-end(s) will not be received at the local end(s), meaning no Tx switch
will occur.
• If the link failure is due to a Tx failure, the silent transmitter command from
the far end will initiate a switch to the standby Tx at the local end (the
secondary RAC is the default standby Tx).
• Auxiliary data circuits and any payload circuits configured for point-to-point
operation are not protected in the event of a ring wrap (as for a ring operation
using 1+0 links).
• NMS is supported on the 1+1 ring links (as for ring operation using 1+0 links).
• Standard ring diagnostics are supported at the ring level, and operate
independently of the 1+1 diagnostics.
• Standard 1+1 link diagnostics are supported on the 1+1 ring links.
Co-channel XPIC Operation on a Ring
Using RAC 40s for Co-channel Dual Polarized (CCDP) operation, two
independent Super-PDH protected rings can be established over the same ring
topology and on the same frequency by using the vertical and horizontal
polarizations.
• Standard RAC 40 configuration procedures are used on each of the ring links.
• The capacities supported are the standard PDH RAC 40 rates of 64x, 75xE1 or
70x, 84x, 100xDS1. However for single-gateway rings (all ring traffic sourced
and sunk through one ring site), the Node backplane maximums mean the
maximum usable capacities are 64xE1 or 70x, 84x DS1.
• Two co-located INUs are required at each ring node. Each supports an east and
west RAC 40.
For more information on RAC 40 CCDP operation refer to Co-channel Operation
on page 3-102.
A ring wrap occurs when the path provided by the space diversity link fails, or a
Tx or Rx online switch event occurs on the space diversity link, or both space
diversity receivers trigger a demodulator not locked alarm.
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A silent transmitter switch is designed to prevent an undetected transmit failure from causing a link to go
down indefinitely.
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