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Community Member

power supply for 6500

Dear All,

When I use power calculator ( to calculate the power supply needed for a 6500 (e.g. 6509E) switch. If I use a sup7203B with 4 x WS-X6748-GE-TX (with DFC3a), 1 x WS-X6704-10GE (with DFC3B) and 3 x WS-X6748-SFP (with DFC3A). The result display that the total power is 3323.88w and need a 4000w primary power supply. But the strange thing is, the result also display:

First Alternative Power Supply

Combined WS-CAC-2500W

So that means I can use a 2500w power supply as secondary power supply? or means that I need to use 2 x 2500w power supply? if I use 2500w power supply, what happen if 1 x 2500w power supply fails?

Thank you!

Best Regards,

Teru Lei


Re: power supply for 6500

You would need 2x2500 PS. If one were to fail, line cards would start to shut down and possibly the SUP! If you buy 2x4000 PS you can lose a PS and the switch will stay up and running.

Hope that helps

Community Member

Re: power supply for 6500

Collin nailed it - you can either run the PSU's in combined or redundant mode. Combined mode allows lesser PSU's to be used however as Collin noted, if you lose a PSU, you start dropping line cards as you now cannot meet the power capacity requirements of your box.

Best bet - 2x 4000w, if the budget allows.

Community Member

Re: power supply for 6500

Thanks for the reply. But I wonder if in 2 x 2500w, one power supply fails and some line card drop, and that may cause performance issue. e.g. HSRP, routing and spanning-tree. Seems it's better to shutdown the whole switch in this case. Is there any document to describe this scenario??


Re: power supply for 6500

Then you should buy one 4500w (and maybe another one as a shelf spare).

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