Cisco Systems AS5800 manual Dial Shelf DC-Input Power Supply, Common Logic Interface

Dial Shelf Field-Replaceable Units

Table 1-5	Dial Shelf Controller Card Front Panel Ports
Port		Description
Console		Provides RJ-45 connection to the system controller
		console port for system management.
Network clock		Provides BNC connection for an external T1 or E1
		reference input signal from which a clock is extracted.
Alarms		Provides DB-15 serial connection to an external audio
		or visual alarm source.
10BaseT		For Cisco internal use only.
Dial shelf interconnect		Provides RJ-45 cable connection to the router shelf.

Common Logic Interface

Each DSC card contains a block of logic referred to as the common logic and system clocks. This block generates the backplane Stratum-4 compliant 4-MHz and 8-kHz clocks used for interface timing and for the TDM bus data movement. The common logic can use a variety of sources to generate this system timing, including an E1 or T1 signal input from the BNC connector on the dial shelf controller card front panel.

Only one common logic is active at a time, identified by the CLK LED on the DSC card front panel. The active common logic is user-selectable and is independent from each DSC card. This assures that if you need to replace a DSC, or if the slave dial shelf controller card becomes the master, clocking remains stable. The selected common logic should not be changed during normal operation unless a hardware failure is suspected or diagnosed in the DSC card.

Dial Shelf DC-Input Power Supply

The Cisco AS5800 is equipped with two power-entry modules (PEMs) in the dial shelf, which accept DC-input power either from your site DC source or from an optional AC-input power shelf, and distribute –48 VDC power to the dial shelf components. The PEMs provide power redundancy and load-sharing; however, a single PEM can power a fully configured system.

Note Whenever possible, we recommend that you connect each PEM to a separate DC power source.

The PEMs and the filter module are cooled by system air flow, which flows from the top to the back of the dial shelf chassis. The front and sides of the PEMs are perforated for minimum air flow restriction.

The PEMs support the following functions:

•Power redundancy and load sharing

The DC-input power supply provides redundant power by design. During normal operation, the two PEMs provide system power simultaneously (load share). When you remove one PEM, the remaining PEM immediately ramps up to provide full power and maintain uninterrupted system power.

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