Cisco goes green with Catalyst 3750-X

Cisco delivers cost savings by creating power pool within switch stack

Buy less equipment, use less power: That's a proposition network managers can get behind, and it's what Cisco promises with the new power management features in its Catalyst 3750-X stackable access switch.

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As this exclusive Clear Choice test demonstrates, Cisco makes good on that promise with StackPower, a means of pooling power among switches in a stack. Testing validated that StackPower can cut both capital and operational costs.

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Buy less equipment, use less power: That's a proposition network managers can get behind, and it's what Cisco promises with the new power management features in its Catalyst 3750-X stackable access switch.

Read daily news about Cisco

As this exclusive Clear Choice test demonstrates, Cisco makes good on that promise with StackPower, a means of pooling power among switches in a stack. Testing validated that StackPower can cut both capital and operational costs.

The switches also support PoE+, a new method of lighting up power-hungry Web cameras, 802.11n Wi-Fi access points, and other devices requiring more juice than the old PoE standard can supply.

Click to see: INFOGRAPHIC: StackPower saves on capital, power costs

We verified full PoE+ operation on 48 switch ports concurrently, and ran the switch through a rigorous battery of conformance tests developed by Sifos Technologies. Those tests turned up only minor issues, none of which should affect interoperability.

The 3750-X offers other new features, such as MACSec encryption and Smart Operations deployment software, on top of what is already a lengthy features list. We focused on the new switch's power management capabilities.

Power-sharing arrangement

StackPower offers a means of pooling power supplies within a stack and making wattage available to any switch as needed. The advantages include savings on power and power supplies; redundancy with no extra footprint; and a prioritization scheme that first cuts power to lower-priority ports in case a power supply fails.

StackPower connections are conceptually similar to the StackWise Plus links supported in earlier Catalyst 3750 switches, with multiple switches connected in a ring topology. The switches continue to share power if a connection fails, something we verified in testing. (While StackPower works only with the new X series switches, StackWise Plus works between newer and older Catalyst 3750 models.)

Ethernet cheat sheet

Up to four Catalyst 3750-X switches can form a StackPower ring. This is fewer than the nine switches supported in StackWise Plus. However, a nine-switch StackPower unit still can be formed through the use of an XPS-2200, an external redundant power system that connects to the switches using a star topology. We did not test the XPS-2200.

Cost savings is StackPower's most obvious benefit. Given the importance network managers typically place on high availability, it's not uncommon to find redundant power supplies in every switch throughout the enterprise. With StackPower, it's possible to purchase fewer power supplies and still obtain N+1 redundancy for power supplies in a ring (or N:1 redundancy if using the XPS-2000).

For example, if each of three switches in a stack consumes 200 watts, the aggregate power draw is 600 watts. With 715-watt power supplies, full N+1 redundancy would involve six power supplies at $1,000 each, supplying up to 4,290 watts.

In contrast, the StackPower could run the same stack with as few as two 715-watt power supplies. That's a savings of four power supplies or $4,000, and a rated capacity of only 1,430 watts, with the same level of redundancy.