2 x 3750X stackpower - 1 or 2 stackpower cables needed

[will]

hi, just got some new toys: 2 x 3750x stacking switches. have worked with the data stack before and understand why we need 2 cables to stack 2 switches: increased throughput and a little bit of data plane redundancy. However, regarding stack power, im not sure if you have just 2 switches, whether we really need two stack power cables. both switches can run on their own with their own individual power supply. So if the one primary stackpower cable goes away, switches will be fine on their unique power supplies. therefore, im having a time to understand if we really need to connect 2 switches with _both_ stackpower cables. Seems like no real advantage.

FYI... in case you are wondering: "Why even worry about this, just connect them up with the 2-free supplied cables?" Well, we need to purchase the extra long stackpower cables to go cross-rack, rather then rack-vertical. So just wondering if we really need to buy two cables.

thx in advance,

Will

[Leo Laohoo]

Yes.  You need two.

[Reza Sharifi]

Hi,

It will work fine with just one power cable connected.  You can actually test it by disconnecting the power cord to one of the switches. One switch will run of the other switch. The reason for 2 is that you can daisy chain multiple switches together.  Have a look at figure-6 in this link and read about the use case for power sharing.  It is mostly for cases when you have POE and none POE switches with different types of power supplies in the same stack.

http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps6406/white_paper_c11-578931.html

HTH