Alcatel-Lucent 1665 DMX supports path switched ring applications using the path protection switching schemes described in Telcordia ® GR-1400. This scheme offers 60-millisecond restoration times and simple network administration for access applications. The ring facility consists of two fibers, with service and protection rotating in opposite directions. Each input is bridged and transmitted in both directions around the ring. The receiving end terminal monitors the quality of both signals and selects the best signal to drop.
Alcatel-Lucent 1665 DMX supports the following OC-3/OC-12/OC-48/OC-192 path switched ring configurations:
Path protection is user-provisionable on a per-cross-connection basis when the port is set to UPSR. A manual path protection switching command allows switching to the other path for ease of ring maintenance. STS-n path switching is non-revertive and is triggered by path defects Path AIS (AIS-P), UNEQ-P, LOP-P, SF BER (excessive BER) and SD. The system also supports VT path protection switching based on VT AIS (AIS-V), LOP-V, UNEQ-V, and VT SD. Line level defects (LOS, LOF, AIS) indirectly contribute to path switching because these errors generate downstream path AIS (AIS-P).
By supporting protection mode provisioning on a per port basis, Alcatel-Lucent 1665 DMX provides for the mixing of protection modes across the ports of a multi-port pack.
On the WAN (SONET) side of the network, Alcatel-Lucent 1665 DMX utilizes standard IEEE 802.1D and fast 802.1w spanning tree protection for multipoint applications and/or STS-1 UPSR protection (for point-to-point applications).
In the "locked" mode, Alcatel-Lucent 1665 DMX does not select the best signal from both rotations of a UPSR. Instead, traffic is added and dropped (locked) from one rotation of the ring only (provisionable). The main advantage of locked VT cross-connections is the lack of UPSR switching which results in the ability to reuse time slots around a UPSR.
Locked cross-connections are only used in systems that are not equipped with VLF Mains because VLF mains allow unprotected (linear) UPSR cross-connections which allow users to independently provision cross-connections on UPSR tributaries. In systems with non-VLF Mains, once a locked cross-connection is established from a UPSR tributary, the companion tributary cannot be cross-connected.
Alcatel-Lucent 1665 DMX has the ability to mix locked, unlocked, and pass-through VT1.5s within the same STS-1, and to allow both rotations of a ring to be used simultaneously.
Alcatel-Lucent 1665 DMX provides an unprotected cross-connection mode, referred to as Linear/Unprotected UPSR, on OC-3/12/48 low-speed ports and OC-3/12/48/192 high-speed UPSRs. Alcatel-Lucent 1665 DMX allows both rotations of a ring to be used simultaneously. Simultaneous 1WAY cross-connections can be sourced from the 2 associated ring channels in a UPSR application. Simultaneous 1WAY cross-connection can be sourced from a ring channel. Support is also provided for 1WAY or 1WAYPR destined to the associated ring channel.
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