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Understanding TCX1000-RDM20 and TCX1000-2D8CMD Multiplexing Capabilities

 

Introduction

The TCX1000-RDM20 has twenty universal ports that you can use for directly adding/dropping channels onto a ROADM degree, passing channels through from one ROADM degree to another, or for connecting an optical multiplexer-demutiplexer to add/drop more channels to the TCX1000-RDM20.

This section describes how you can use the TCX1000-2D8CMD multiplexer with the TCX1000-RDM20 for both single and multi-direction colorless add/drop multiplexing. This section also describes how multiplexing and demultiplexing works in this configuration for both directly added/dropped channels and pass-through channels.

Note

The TCX1000-2D8CMD client ports require coherent transceivers.

Single Direction Add/Drop Colorless Multiplexing with TCX1000-2D8CMD

Figure 1 shows a 2-degree linear multi-span ROADM node. The top portion shows the physical interconnections needed to create the ROADM node. The bottom portion shows the logical node configuration.

Figure 1: Single Direction Add/Drop Colorless Multiplexing with TCX1000-2D8CMD
Single Direction Add/Drop
Colorless Multiplexing with TCX1000-2D8CMD

In Figure 1 is a ROADM node that includes two elements, RDM20-A and 2D8CMD-A form one ROADM element serving degree 1 and RDM20-B and 2D8CMD-B form another ROADM element serving degree 2. This 2-degree node provides single direction colorless multiplexing for connected channels; connected channels are always routed out the ROADM degree that they are physically connected to. As such, in this configuration, you can add/drop channels for direction 1 by connecting your transceivers to either RDM20-A or 2D8CMD-A and you can add/drop channels for direction 2 by connecting your transceivers to either RDM20-B or 2D8CMD-B.

Also in this ROADM node configuration, a single universal port on each TCX1000-RDM20 is used to pass channels between the two ROADM degrees. Another universal port connects the line port of the TCX1000-2D8CMD multiplexer. This configuration leaves you 18 universal ports on RDM20-A and 18 universal ports on RDM20-B, as well as 8 additional ports on each TCX1000-2D8CMD.

The following sections describe how multiplexing and demultiplexing works for directly connected add/drop channels and for pass-through channels in this configuration.

Multiplexing

Add/Drop Channels

  • Channels directly connected to the clients ports (Cx) on 2D8CMD-A are combined and broadcast out the Lx Out port(s) to the connected universal port on RDM20-A, which multiplexes the channels and routes them out degree 1.

  • Channels directly connected to the clients ports (Cx In) on 2D8CMD-B are combined and broadcast out the Lx Out port(s) to the connected universal port on RDM20-B, multiplexes the channels and routes them out degree 2.

Pass-Through Channels

The configuration in Figure 1 enables you to pass through channels between degree 1 and degree 2:

  • Pass-through channels from direction 1 are received on the line port of RDM20-A, which demultiplexes the channels and sends it out the universal port on RDM20-A to the universal port on RDM20-B. RDM20-B multiplexes the pass-through channel and sends it out direction 2.

  • Pass-through channels from direction 2 are received on the line port of RDM20-B, which demultiplexes the channel and sends it out the universal port on RDM20-B to the universal port on RDM20-A. RDM20-A multiplexes the pass-through channel and sends it out direction 1.

Demultiplexing

Add/Drop Channels

  • Channels coming in from direction 1 are demultiplexed by RDM20-A and dropped to the appropriate universal port. Channels destined to 2D8CMD-A, now present at Lx In port of 2D8CMD-A , are broadcast to the 8 channel output ports (Cx Out ports) on 2D8CMD-A.

  • Channels coming in from direction 2 are demultiplexed by RDM20-B and dropped to the appropriate universal port. Channels destined to 2D8CMD-B, now present at the Lx In port, are broadcast to the 8 channel output ports (Cx Out ports) on 2D8CMD-B.

Note

The connected coherent transceivers are responsible for selecting their corresponding wavelength and filtering out the impact of the unwanted broadcast channels. As such, the TCX1000-2D8CMD is suitable for coherent only applications.

Pass-Through Channels

  • A pass-through channel coming in from direction 1 is demultiplexed by ROADM element RDM20-A and sent out the Ux Out pass-through port on RDM20-A to the Ux In pass-through port on RDM20-B, which multiplexes the pass-through channel and sends it out direction 2.

  • A pass-through channel coming in from direction 2 is demultiplexed by ROADM element RDM20-B and sent out the Ux Out pass-through port on RDM20-B to the Ux In pass-through port on RDM20-A, which multiplexes the pass-through channel and sends it out direction 1.

Summary of Colorless Single Direction Multiplexing

Figure 2 summarizes colorless single direction multiplexing.

Figure 2: Colorless One-Direction Multiplexing
Colorless One-Direction
Multiplexing

Coherent transceiver interfaces connect to the eight client ports on the TCX1000-2D8CMD. The line port of the TCX1000-2D8CMD connects to a single Ux port on the TCX1000-RDM20. The TCX1000-2D8CMD can be thought of as an 8:1 port expander. This configuration provides channel ports that are:

  • Colorless

  • Single direction (direction is defined by the connected TCX1000-RDM20 degree)

Note

There is no spectral policing on the TCX1000-2D8CMD, so that if the same channel is applied to two or more client ports of a single TCX1000-2D8CMD, interference can occur between the channels.

Note

This configuration does not work with non-coherent channels.

Multi-Direction Add/Drop Colorless Multiplexing with TCX1000-RDM20 and TCX1000-2D8CMD

Figure 3 shows a 2-degree linear multi-span ROADM node that supports multi-direction add/drop capability. The top portion shows the physical interconnections needed to create the ROADM node. The bottom portion shows the logical node configuration.

Figure 3: Multi-Direction Add/Drop Colorless Multiplexing with TCX1000-RDM20 and TCX1000-2D8CMD
Multi-Direction
Add/Drop Colorless Multiplexing with TCX1000-RDM20 and TCX1000-2D8CMD

The 2-degree ROADM node in Figure 3 provides multi-direction add/drop colorless multiplexing by leveraging the TCX1000-2D8CMD dual line ports. In this node configuration, a single universal port on each ROADM element (RDM20-A and RDM20-B) is used for a pass-through connection. Another universal port on each ROADM element connects to the two line ports (Lx) of the TCX1000-2D8CMD. This configuration leaves you 36 universal ports for add/drop traffic: 18 universal ports on RDM20-A and 18 universal ports on RDM20-B, as well as 8 additional ports on the TCX1000-2D8CMD.

The following sections describe how multiplexing and demultiplexing works for directly connected add/drop channels and for pass-through channels in this configuration.

Multiplexing

Add/Drop Channels

Channels directly connected to the Cx In ports on ROADM element: 2D8CMD-A are combined and broadcast out both Lx Out ports to the connected universal ports on RDM20-A and RDM20-B. Channels configured to take the path to direction 1 are multiplexed by RDM20-A and sent out direction 1. Channels configured to take the path to direction 2 are multiplexed by RDM20-B and sent out direction 2.

The TCX1000-2D8CMD broadcasts the same composite signal out both line ports and the ROADM (TCX1000-RDM20) elements manage the channel selection. This allows a channel connected to the TCX1000-2D8CMD to be routed out either degree 1 or degree 2 of the ROADM node. This provides flexibility to re-configure the network remotely, allowing for rapid re-configuration of services, tidal traffic flow or automated optical restoration applications.

The TCX1000-2D8CMD provides the simplest form of a multi-direction solution where the output from the 8 to 1 combiner is broadcast in 2 directions. This is primarily intended for 1 + 1 redundancy applications.

Note

The TCX1000-2D8CMD broadcasts channels present on the Cx In ports out both Lx Out ports. You specify the path for these channels on the TCX1000-RDM20 when you define the channel service.

Pass-Through Channels

The 2-degree ROADM node in Figure 3 enables you to pass through channels from degree 1 to degree 2 and from degree 2 to degree 1:

  • Pass-through channels from direction 1 are received on the line port of ROADM element: RDM20-A, which demultiplexes the channel and sends it out the universal port on RDM20-A to the universal port on RDM20-B. RDM20-B multiplexes the pass-through channel and sends it out direction 2.

  • Pass-through channels from direction 2 are received on the line port of ROADM element: RDM20-B, which demultiplexes the channel and sends it out the universal port on RDM20-B to the universal port on RDM20-A. RDM20-A multiplexes the pass-through channel and sends it out direction 1.

Demultiplexing

Add/Drop Channels

Channels coming in from direction 1 that are destined for ROADM element: 2D8CMD-A are demultiplexed by RDM20-A and sent over the universal port to the connected line port on 2D8CMD-A. 2D8CMD-A demultiplexes the channels and broadcasts them to the Cx Out ports.

Channels coming in from direction 2 that are destined for ROADM element: 2D8CMD-A are demultiplexed by RDM20-B and sent over the universal port to the connected line port on 2D8CMD-A. 2D8CMD-A demultiplexes the channels and broadcasts them to the Cx Out ports.

Note

The TCX1000-2D8CMD broadcasts channels present on the Cx In ports out both Lx Out ports. You specify the path for these channels on the TCX1000-RDM20 when you define the channel service.

Pass-Through Channels

  • A pass-through channel coming in from direction 1 is demultiplexed by ROADM element RDM20-A and sent out the Ux Out port on RDM20-A to the Ux In port on RDM20-B, which multiplexes the pass-through channel and sends it out direction 2.

  • A pass-through channel coming in from direction 2 is demultiplexed by ROADM element RDM20-B and sent out the Ux Out port on RDM20-B to the Ux In port on RDM20-A, which multiplexes the pass-through channel and sends it out direction 1.

Summary Colorless 1+1 Redundancy Multiplexing

Figure 4: Summary Colorless 1+1 Multiplexing
Summary Colorless 1+1
Multiplexing

Figure 4 summarizes colorless 1+1 redundancy multiplexing. Coherent transceiver interfaces connect to the eight TCX1000-2D8CMD client ports. The two line ports from the TCX1000-2D8CMD each connect to a single universal port on TCX1000-RDM20. This configuration provides channel ports that are:

  • Colorless

  • Multi-direction — channels can be sent/received in two directions, as determined by the TCX1000-RDM20 configuration

Note

The TCX1000-2D8CMD broadcasts channels present on the Cx In ports out both Lx Out ports. The configuration of the connected TCX1000-RDM20 is responsible for determining which channels are multiplexed by the TCX1000-RDM20 and sent out its line port.