Single PSUs on 3750s and 3560s any solution?

[Andy White]

Hello,

Weird question here, we have a bunch of 3750's and 3560 that have their single PSU's going into either of our 2 UPS's so they don't have any power redundancy should we lose a UPS.  Is there such a UPS cable that can come out of the single PSU port of a switch and go into both UPS's?

Thanks

[Gregory Snipes]

You should probably look into getting an RPS. Depending on the age of your equipment you may need to get either an RPS 2300 or an RPS 675 which is now end of sale but should still be obtainable.

Edit: Upon further examination it appears that they make a backwards compatible cable for the RPS 2300, so the RPS 2300 should work regardless of the age of the equipment.

The important thing here is that even if you were to get some kind of transfer switch to allow you to connect the switches to two UPS, you would still not be redundant as the power supply inside the switch is still a single point of failure. The RPS provides real redundancy, in the case of either an UPS or switch power supply failure.

[Andy White]

Thansk for this, so do you just plug your switches into one of these devices then?  Is it possibel to add another PSU to a 3750?

[Gregory Snipes]

Each RPS 2300 has two power supplies in it each of witch can power a switch. So for maximum redundancy I would say for each pair of switches install one RPS. Plug each of the switches into separate UPSs, then plug each of the RPS power supplies into two separate UPSs. You then use the RPS cables to connect the RPS to the DC input ports on the back of the switches.

Basically in the event of a power supply failure (or power supply input failure) the RPS will continue to send DC power onto the system power bus of the switch in place of the internal power supply.

The RPS is how you add an extra power supply to a 3750. It needs to external as there is no extra room inside the casing.