Difference between 1:1 and 1+1 Power Option

[Noy-pi]

hi,

can someone explain the difference between 1:1 and 1+1 power option for Cisco switches? any links for such explanation?

thank you,

shawn

[Reza Sharifi]

Hi,

Have a look:

http://en.wikipedia.org/wiki/N%2B1_redundancy

Also:

N+1 Power Supply Unit Redundancy (default): In  this mode, protection against a single power supply unit failure is  provided. In the event of a single power supply failure, loads are  redistributed using available capacity across remaining functional power  supply units. N+1 redundancy is available with either 2 or 3 power  supplies installed in the system. The total available power to the  chassis is the sum of all installed power supplies minus that of the  largest (for redundancy). This is the default power redundancy mode.

Nexus Series power supply redundancy:

http://www.cisco.com/en/US/prod/collateral/switches/ps9441/ps9402/ps9512/White_Paper_Continuous_Operations_High_Availability.html

HTH

[newbieregarded]

What about 1:1? What does that mean?

[Ramblin Tech]

1:1 redundancy means that for each component protected by redundancy, there is a 1:1 relationship with a redundant, fail-over component. In the above example, from 2013, 1:1 and 1+1 are effectively the same. That is, the system can operated on one PSU, but there is a second PSU installed for redundancy. If the system required two PSUs to operate (N=2), the 1:1 redundancy model would have a total of four installed (two redundant pairs), but the N+1 model would need only three (the third PSU protects both of the other two PSUs).

[Joseph W. Doherty]

Here's, I believe, the same question posted some years ago on a different forum.

[Edit - addendum]

Here's a Cisco StackPower White paper that describes 1:1, 1:N and 1+N (not mentioned is 1+1, but should be a subset of 1+N).