TX Matrix Fiber-Optic Array Cable Considerations

The fiber-optic array cables connect the switching planes of the T640 routers to the TX Matrix router by connecting the T640-SIBs to the TX-SIBs. When planning your installation site, consider the following fiber-optic array cable requirements:

• You must use the same length for every fiber-optic array cable from a particular T640 router to the TX Matrix router. However, you do not need to use the same length for all fiber-optic array cables within a routing matrix. For example, if your routing matrix contains two T640 routers, you can use 6-meter fiber-optic array cables to one router and 100-meter fiber-optic array cables to the other router.
• You must maintain a minimum bend radius of 2 in. (5.1 cm). We recommend that you maintain a bend radius of 10 in. (25.4 cm). If you must bend a fiber-optic array cable to a 2-inch radius, we recommend that you do not use more than two such bends.
• Plastic wrap-ties can damage or crimp the fiber-optic array cables (see Figure 1). We recommend that you use soft band straps to secure fiber-optic array cable.

  Figure 1: Using Soft Band Straps to Secure Fiber-Optic Array Cables

  
• The fiber-optic array cable connectors must fit through your site's cable conduits. For the connector dimensions, see Figure 3.

In addition, consider the following when planning your installation site:

• Make sure any existing T640 routers are close enough to the location of the TX Matrix router, particularly in a distributed configuration. Consider the length of the longest fiber-optic array cables (100 meters), along with their routing through overhead raceways and mounting racks.
• When you plug a fiber-optic array cable into a T640-SIB, the cable extends toward the left side of the T640 router (as viewed from the rear of the chassis) due to the horizontal orientation of the connectors (see Figure 2). To facilitate the fiber-optic array cable routing, particularly in a centralized configuration, we recommend that you install the TX Matrix router to the right of the T640 routers (as viewed from the front of the chassis). This chassis placement might allow you to use shorter fiber-optic array cables—such as 4 m or 5 m—and helps you manage the bend radius of the cable. See TX Matrix Routing Matrix Hardware Configurations for an illustration of the recommended centralized configuration.

  Figure 2: T640-SIB

  
• Plan the management of the fiber-optic array cables between the T640 routers and the TX Matrix router, keeping in mind the following considerations:
  • With four T640 routers, you can have a total of 20 fiber-optic array cables in a routing matrix.

    Note: We recommend that you purchase one additional fiber-optic array cable for each T640 router in the TX Matrix router in case one of the cables becomes damaged. We recommend that you route the spare cables when you route the main cables, particularly in a distributed configuration.

  • The fiber-optic array cables must not interfere with TX Matrix router and T640 router airflow and maintenance access. For an illustration of the TX Matrix router airflow, see TX Matrix Clearance Requirements for Airflow and Hardware Maintenance.
  • The fiber-optic array cable weighs 0.22 lb (0.10 kg) per meter and each cable connector weighs 0.5 lb (0.23 kg).
  • With four T640 routers, you can have a total of 128 PICs in a routing matrix, and each PIC can contain up to 10 cables (for example, the 10-port Gigabit Ethernet PIC), for a total of 1,280 cables. Consider PIC cabling as part of your overall cable management planning. For more information about PICs and their cables, see the T640 Core Router Hardware Guide  and the T640 Core Router PIC Guide .

Figure 3: Fiber-Optic Array Cable