Cisco WS-X4604-GWY - VoIP Gateway Especificaciones descargar pdf (Pagina 53)

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Cisco IP Telephony Network Design Guide

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Chapter 2 Campus Infrastructure Considerations

Power to IP Phones

Figure 2-8 External Power Through the Power Patch Panel

As shown in Figure 2-8, pairs 2 and 3 from the switch are patched straight through

to pairs 2 and 3 coming from the phone. Pairs 1 and 4 from the phone terminate

at the patch panel (Ethernet does not use pairs 1 and 4) and power is applied across

them to power the phone. The actual conductors used are pins 4 and 5 (pair 1) and

pins 7 and 8 (pair 4) for power and ground return. This means that all four pairs

in the Category 5 cable need to be terminated at the user’s desk and in the wiring

closet.

The Cisco power patch panel operates in discovery mode. In discovery mode, the

patch panel tries to verify if the device connected to it is a Cisco IP Phone. It does

this by using the phone discovery mechanism used in the inline power method,

except that here the patch panel, rather than the switch, generates the test tone.

Everything else about the process is identical to that described in the

“Establishing Power to the IP Phone” section on page 2-12.

Switch side

RJ-45

Switch port

without

inline power

Phone side

RJ-45

Power

Pair 4

Pair 1

Cisco IP phone

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Cisco WS-X4604-GWY - VoIP Gateway Especificaciones Pagina 53