Cisco AS5850 Manual do Utilizador descarregar pdf (Página 4)

Universal Gateway by preventing CPU- and memory-overload conditions that could cause ERSC failure. The CPU adjusts to “the DSP

auto-busy” algorithms when memory is low or CPU is high.

Hot-Swapping on all Cards and Modules

Hot-swapping on all cards and modules allows hardware maintenance to be performed on an active access server with little or no service

interruption. During a hot-swap, any card may be replaced, and only the calls on the card being removed are affected. “Soft busy”

commands can be used to gracefully remove traffic before card removal.

The power entry modules (PEMs) are load-sharing and fully redundant, with separate power feeds and separate breakers. In the unlikely

event of a PEM failure, the failed unit can be removed and replaced while the system continues normal operation. The cooling module can

be easily hot-swapped if necessary. The optional managed AC supply has hot-swappable modules and N + 1 power module redundancy.

Thermal Management

Twelve adjustable-speed fans in three N + 1 redundant banks provide cooling for the Cisco AS5850 Universal Gateway. If one fan in a

bank fails, the others automatically increase speed (thereby increasing airflow) to compensate for the lost fan. If a fan-controller fault

occurs, all fans automatically run at full speed. A fan failure or fan-controller failure causes the ERSC to generate an alarm. Redundant

power feeds to the fan controller help ensure power to the fans and controller.

Thermal sensors are installed on each card near the air inlet and outlet positions to monitor the inlet and outlet temperatures and

temperature rise across each card. The fans increase speed in case of high-temperature readings, providing additional cooling in

extreme conditions. If an individual feature card within the dial shelf exceeds its maximum operating temperature, only the affected

board is shut (powered) down.

If the system continues to exceed its maximum operating temperature, the thermal sensors initiate further shutdowns, preventing damage

to the unit or its surrounding environment from excessive heat. An incremental shutdown sequence targets DSP cards first and trunk

interfaces last to avoid alarms in the central-office switch.

The thermal performance margin of the Cisco AS5850 Universal Gateway cooling system allows a Cisco AS5850 to operate at full capacity

for up to 15 minutes with the hot-swappable cooling module removed during a cooling module exchange.

Hot Spares

The Cisco AS5850 Universal Gateway can be configured with spare DSPs for added resiliency. Because DSPs are pooled and allocated

on a call-by-call basis, a DSP failure will not cause a DS-0 or B channel to be left without a DSP to terminate the call, preventing the

occurrence of “stranded ports” or unused channels within a hunt group. Having spare DSPs in the pool also allows DSP code to be updated

without affecting active calls. There can be more DSPs in the DSP pool than available DS-0 interfaces to cover for resources that are being

upgraded or tested.

DSP Resource Recovery Feature

DSP resources are tested at power up and after disconnect to check for faults. Any defective DSPs found are moved to the resource

recovery pool. An automatic recovery feature can be turned on to recover defective DSPs in the recovery pool and added back into the

resource pool if possible.

Redundant Data Paths

The Cisco AS5850 Universal Gateway provides multiple paths for data packets from a DS-0 to an external backbone device. Redundant

packet buses exist from each feature card slot to both ERSCs along with multiple separate time-division multiplexing (TDM) buses for

expansion and resiliency. Backhaul redundancy to the IP core network is accomplished using the redundant backhaul Gigabit Ethernet

interfaces provided on each ERSC.

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