Figure 36: T640-Sib - Juniper TX MATRIX Hardware Manual

TX Matrix Hardware Guide
66
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 36 on page 66). 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" on page 58 for
an illustration of the recommended centralized configuration.

Figure 36: 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" on
page 63.
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
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