Stack Power Group WS-C3750X-12S-E with WS-C3750X-48P-E

[Chris Gill]

So we have a couple network uplifts this year where the core will be two WS-C3750X-12S-E (350w powre supply) stacked with two WS-C3750X-48P-E (715w Power Supply) for a single four switch stack.

My question is can this be setup as a singe Stack Power group so that the 715w supplies in the WS-C3750X-48P-E can be used as backups for the 350w supplies in the fiber WS-C3750X-12S-E?  If not I will have to set the WS-C3750X-12S-E as their own stack power group and the other switches as their own.

We will also have a spare power supply in one of the WS-C3750X-48P-E for a total of 5 power supplies for the stack.

[Reza Sharifi · Accepted solution]

Yes, you can have the larger PSUs backup the stack.

See figure-6 in this link:

http://www.cisco.com/c/en/us/products/collateral/switches/catalyst-3750-x-series-switches/white_paper_c11-578931.html

HTH

[Chris Gill]

Thank you.  When I looked at that figure in the white sheets I saw the Xs and was thinking that it couldn't be done.

[Joseph W. Doherty · Accepted solution]

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Posting

(Bear with me.  This question seems very much like one I posted to the other day, but with the new revised forums, I'm unable to find that recent posting.)

As Reza has noted, yes you can.  However, you need to determine if there will be sufficient excess power if a 350W PS fails.  There's also the converse, whether there's sufficient excess power if a 715W PS fails.  Much will depend on how much PoE you'll be drawing on the 48Ps.

The extra PS (also 715W) should make it more likely you'll have enough excess power.

There is a limit, though, of 2000W via a StackPower cable.  So, ideally, you'll want to place power supplies to minimize the need to draw power through the StackPower cables, both normally, and in cases were a PS fails.