Cisco Systems RPS 675 Review

Voice over IP (VoIP), it is the wave of the communications future.  The company I work for converted about two years ago from traditional phone lines.  Goodbye Ma-Bell, hello Cisco.  VoIP phones like the Cisco 7940 IP Phone need an IP address in order to take and make phone calls, but they also need power in the form of Direct Current (DC).  And in order to supply (DC) electrical power over a category 5 cable the phones have to be connected to a network switch that supplies a reliable source of DC power like the Cisco Catalyst 3570-PoE switch.       

Note: Power-over-Ethernet (PoE) or "Active Ethernet" eliminates the need to run 110/220 VAC power to Wireless Access Points and other devices on a wired LAN such as IP Phones. Utilizing PoE system installers need to run only a single CAT5 Ethernet cable that carries both power and data to each device. This allows greater flexibility in the locating of Wireless Access Points AP's and network devices and significantly decreasing installation costs in many cases.

Power-over-Ethernet begins with a CAT5 "Injector" that inserts a DC Voltage onto the CAT5 cable. The Injector is typically installed in the "wiring closet" near the Ethernet switch or hub.  We use our complement of some 100 Catalyst 3750-PoE switches to power and connect our installed base of IP Phones.

In turn the Cisco Catalyst 3570-PoE switch needs a reliable source of DC electrical power, that is where the Cisco Redundant Power System 675 (RPS 675) comes into the picture.  The small 1U rack mount unit is in effect a (backup) power supply designed to provide internal power supply redundancy for up to six Cisco networking devices and provides those devices with an immediate failover capability.  If the internal power supply of one of the connected Cisco Catalyst 3570-PoE switches were to fail the Cisco RPS 675 automatically senses the failure and delivers uninterrupted power to that device.  This in turn guarantees uninterrupted VoIP service for the enterprise.  

The Cisco RPS 675 provides (6) 675W DC outputs to various Cisco devices through rather thick gray cables. The Cisco RPS 675 has two output levels: -48 VDC with a maximum output of 375W and 12 VDC with a maximum output of 300W, for a maximum total output power of 675W. The -48V mode powers telephone systems in

line-powered switches like the Cisco Catalyst 3570-PoE switch.

Cisco RPS 675 Use

Typical deployment of the Cisco RPS 675 finds one unit in each wiring closet per floor supplying redundant power to up to (6) Cisco Catalyst 3570-PoE switches.  There is nothing to configure, no software to install, of firmware to flash.  The Cisco RPS-675 is for all purposes a UPS that provide (DC) power.    So far the units have proved themselves highly reliable; the business has yet to have a Cisco RPS 675 fail or need replacing. 

The only downside of the Cisco RPS 675 is the size of the DC connector cables (CAB-RPS-1614), which may make installation troublesome; it is big and not very flexible. So trying the bend the cable to your will is a challenge. 

Rack mounting the Cisco RPS 675 is simples and straight forward; the unit utilizes industry standard mounting brackets that Cisco provides in the box with the unit.  Note: Cisco provides (2) CAB-RPS-1614 cables in the box with the RPS 675; additional cables will have to be ordered separately for about $45.00 each.    

Conclusion

In today's technology rich environment, where VoIP is becoming the norm a reliable source of DC power is a must.  The Cisco RPS 675 can and does provide that internal redundant power for our complement of Cisco Catalyst 3570-PoE switches.