In this blog post, let’s take a look at the basics of power redundancy, why it’s needed, traditional methods of achieving it, and how you can do it better.
Businesses require a highly available campus network. Network switch power redundancy is a critical component of overall campus redundancy. There are two commonly used power redundancy solutions for switches – full redundancy and partial redundancy. In full redundancy, every switch is attached to two power supplies so that if one goes down, other takes over. This scheme is also called 1:1 redundancy. In partial redundancy, there is one extra power supply for multiple switches. This is also called 1:N redundancy. However, each has its drawback…
Fully redundant power solutions (the 1:1) are often underutilized because every switch has a backup power supply which is idle under normal condition. However, partially redundant power supply (the 1:N) takes time to come online in the event of a power failure leading to outage.
Cisco StackPower provides a revolutionary alternative to power redundancy for the Cisco access switches. StackPower pools the available power supplies in all the switches and makes it available to all of them. The pooling of the power supplies is the most efficient way to distribute power to all the switches equally because the power from the pool can be used by any switch and if a power supply fails, excess power from the pool can be redistributed to the switch in no time. The picture below compares StackPower with traditional power redundancy schemes for a stack of four switches.
As long as the total available power is more than the power in use, StackPower uses the excess power for redundancy. When a power supply fails on a particular switch, excess power is redistributed to that switch. StackPower allows distributing power based on switch and port priorities. This is valuable during power outages because if the StackPower pool does not have enough power for all switches, certain devices (e.g. Wireless AP’s) connected to certain ports can be kept going until the failed power is repaired.
So, what are the benefits to IT?
- Zero Footprint Redundant Power Supply (RPS): No need to set up an external RPS. Adding one additional power supply to any switch in the stack provides redundancy to entire stack.
- Capital Savings: Avoids purchase and installation of RPS. Conserve real estate in wiring closet.
- Operational Savings: Cisco StackPower frees administrators from maintaining underutilized redundant power supplies and power shelves.
- Scalable: You can connect up to 9 switches with an eXpandable Power System (XPS)
- Easily Configurable: Assign priorities to switches and ports (connected devices) for higher availability during outages.
If you’re looking to implement StackPower, look no further than the Cisco Catalyst 3750-X switch.
For more information, visit http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps6406/white_paper_c11-578931.html