Cross-connection types

Overview

Alcatel-Lucent 1665 DMX has cross-connect capabilities offering users flexibility in directing traffic flow through systems to support a wide variety of customer applications using one-way and multi-point (data specific) cross-connections.

Making cross-connections

Cross-connections are made by specifying the SONET rate (VT1.5 or STS-n), the end point addresses (AIDs), and the cross-connection type (for example, 1WAY). Each single cross-connection command establishes a 1-way cross-connection.

Atomic cross-connections

Beginning in Release 6.0, Alcatel-Lucent 1665 DMX employs atomic cross-connections for all cross-connect provisioning. Atomic cross-connections are one-way cross-connections between logical ring channels which can be set up and taken down by a single command, and which cannot be broken down into smaller parts. Logical ring channels are the tributaries of a port or port protection group used for transmission in the absence of any line or equipment protection.

Each portion of a 2way cross-connect is provisioned as 1way cross-connects. This provides increased flexibility in provisioning all cross-connects.

For customers who use the WaveStar® CIT, Telcordia ® Operating Systems (OS), and INC this change will be transparent. In order to support atomic cross-connections for the first time, customers employing proprietary OS solutions will need to adjust their cross-connection provisioning procedures.

Bidirectional (two-way) cross-connections

A bidirectional connection can be used to send signals between two high-speed ports (pass-through), two low-speed ports (hairpin or pass-through), and a high-speed and low-speed port (add/drop). Bidirectional cross-connections are supported at the VT1.5, STS-1, STS-3c, STS-12c STS-48c, and STS-192c rates as a function of the port types (OC-3/12/48/192-high speed and low-speed).

Unidirectional (one-way) cross-connections

A one-way cross-connection is a unidirectional connection that can be used to send signals between two high-speed ports (pass-through or hairpin, hairpin with the LNW59, LNW82, or LNW504 only), two low-speed ports (hairpin or pass-through), and a high-speed and low-speed port (add/drop). In add/drop applications, this is used where VT1.5, STS-1, STS-3(c), STS-12(c), STS-48(c), STS-192(c) signals on high-speed channels are cross-connected to low-speed DS1/E1, DS3, EC-1, OC-3, OC-12, OC-48, OC-192 10/100/1000BASE-T, 100/1000BASE-X, or FC-DATA ports. Alcatel-Lucent 1665 DMX allows one-way cross-connections in support of DRI, bridge and roll, and true 0x1 unprotected scenarios.

Hairpinning cross-connections

If VLF Main packs are used in “hairpinning” topologies, all cross-connect and switching functions are centralized on the Main pack. Switching within the fabrics on the tributary (low-speed) OLIUs is disabled and traffic is routed directly to the STS fabric on the Mains, bypassing any VT fabric on the tributary OLIUs. When non-VLF Main packs are used, tributary (low-speed) traffic is routed into the system and back out without ever being placed on high-speed (OC-12, OC-48 or OC-192) interfaces. In addition, in systems with non-VLF mains, VT cross-connections on the LNW45 and LNW49 are optimized to minimize the VT fabric usage on the main packs. For example, hairpins between different VTs on an LNW45 or LNW49 are routed using only the VT fabric on the LNW45 or LNW49, and thus do not consume any VT resources on the main packs.

Alcatel-Lucent 1665 DMX is capable of connecting any input on a circuit pack in a function or growth slot to any output on a circuit pack in the same group (known as inter-fn hairpin). Alcatel-Lucent 1665 DMX also supports intra-port hairpins, by which Alcatel-Lucent 1665 DMX can hairpin between different tributaries in the same port. Hairpin cross-connections to 0x1Sn interfaces is also supported. When a VLF Main circuit pack is installed, hairpin cross-connections between unprotected ports on different slots of the same low-speed group are also supported.

These flexible cross-connect capabilities allow you to use a combination of add/drop and hairpinning of compatible payloads through a variety of interfaces. You can bring traffic in from one remote site and cross-connect it at the VT1.5, STS-1, STS-3c, STS-12c, STS-48c, or STS-192c level back out to other remote sites without consuming any capacity on the ring/line interface.

Locked cross-connections

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, unlocked, and pass-through VT1.5s can be mixed within the same STS-1.

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.

Linear/unprotected UPSR

Alcatel-Lucent 1665 DMX allows both rotations of a ring to be used. Simultaneous 1WAY cross-connections can be sourced from the 2 associated ring channels in a UPSR application. Simultaneous 1WAY cross-connection sourced from a ring channel, and 1WAY or 1WAYPR destined to the associated ring channel are also supported.

Unswitched cross-connections

Unswitched cross-connections are user-provisionable on a per cross-connection basis and support single- and dual-homed ring on ring topologies. Path protection and internal equipment (switch fabric) protection is disabled in unprotected configurations. Unswitched cross-connections on Ethernet/Data packs that do not require VCG pairing are supported, but not required.

Multi-point (data-specific) cross-connections

The data specific multi-point cross-connect is a bidirectional cross-connection between two STS-1 Virtual Concatenation Groups (VCGs) on 100/1000BASE-X/T ports to two different ring interfaces. All multi-point cross-connections are done at the STS-1 level (multi-point cross-connections can also be made at the STS-3c and STS-12c level using the LNW63, LNW64, LNW87. or LNW170 circuit pack. Multi-point cross-connections are used to create packet rings.

Multiple 1WAY UNSWITCHED cross-connections provide unprotected SONET connections to Ethernet circuit packs. Each can be used to form two individual connections. With atomic cross-connections, multipoint cross-connections are provisioned by way of 1WAY UNSWITCHED cross-connects.

Bridged cross-connections

Alcatel-Lucent 1665 DMX supports multicast (1xN) cross-connections where N is limited only by the available cross-connect fabric (for VTs) and the compatible output tributaries. Bridging of an existing cross-connection consists of adding a one-way cross-connection with the same input tributary as that of an existing cross-connection, resulting in a 1x2 multicast from an input tributary to two output tributaries. Alcatel-Lucent 1665 DMX supports bridging for each of the supported SONET cross-connection rates. You can bridge any existing cross-connection to a second output port without impairing the existing signal. Conversely, either half of a bridged signal can be taken down without impairing the remaining cross-connected signal.

Pipe-mode (adaptive-rate) cross-connections

Pipe mode is a fault monitoring and performance monitoring feature whereby each automatically adapts to changes in the constituent payload structure of a provisioned STS-n rate cross-connection. Fault and PM are based on the payloads carried within a cross-connection rather than the cross-connection rate. Path protection switching continues to operate at the provisioned cross-connect rate.

DRI cross-connections

DRI cross-connections, used in Dual Ring Interworking applications, are accomplished by means of a one-way, protected drop from a UPSR, a one-way pass-through, and a one-way add to the same UPSR.

Manual cross-connection rates

The following lists the signals that can be cross-connected:

OCH cross-connections

Optical channel (OCH) cross-connections are supported between dense wavelength division multiplexing (DWDM) compatible circuit packs/pluggable transmission modules. The OCH cross-connections are used to inform the network element about manual fiber connections.

OCH cross-connections to/from OCH ports allow the network element to enable alarm reporting and variable optical attenuators. The variable optical attenuators are enabled only when an OCH port is the destination of an OCH cross-connection.

OCH cross-connections to/from OTU2 ports allow the network element to enable alarm reporting and assign the 10G Muxponder internal STS cross-connection fabric to the provisioned client ports.

The following OCH cross-connections are supported:

Important!

In order to support pass-through cross-connections, the LNW785 OMD circuit pack requires external optical amplification.

The following circuit packs are DWDM compatible:

Compatible DWDM optical signals that are terminated by other network elements are also supported (alien wavelengths).

November 2011Copyright © 2011 Alcatel-Lucent. All rights reserved.