APPLICATION TO PURCHASE LINES
A poe ethernet switch 12 port purchase starts from the devices on the far end of the cable, not from a chassis photo. LinkScope Sourcing 15 turns that application into rows a factory can price: port class, total watts, uplink, and the closet constraints.
List cameras, wireless access points, phones, or door controllers. For each, write the PoE class the device asks for. A mix of 802.3af and 802.3at loads on twelve ports is common. Add the watts after each device datasheet is in the folder. Do not multiply twelve by 30 W and call it the requirement.
Ask the switch supplier for the total PoE budget of the named 12-port model and for the budget that remains when the uplink and the fans are running. A 180 W or 240 W figure you have seen on other units is a prompt, not a value for this model. The reply has to quote its own supply.
A closet that feeds cameras and nothing else may stay unmanaged if the NVR handles VLANs upstream. A closet that also carries staff traffic usually needs managed VLANs, and sometimes 802.1X. Write that split before the price column exists. Fast Ethernet at 100 Mb/s can still be enough for a single camera stream. Gigabit is the row to request when the same switch also uplinks several access points.
Depth, temperature, and whether the supply is internal decide if the unit fits the cabinet. An outdoor enclosure needs the operating range from the named model, plus the question of condensation and a surge path. Those limits are not inferred from an indoor 12-port sibling.
Port number, device type, requested class, and cable length. Length matters because powered-device wattage is stated after cable loss. A 100 m run is the usual planning ceiling in premises copper discussions. Your actual run may be shorter. Say so.
Port speed, PoE standard, total budget, switching capacity, and forwarding rate for the exact 12-port model. MAC table size matters when the closet sees many camera addresses plus an uplink trunk.
Wavelength, mode, and reach, kept on a separate price line. Single-mode and multimode are not substitutes. The fiber already in the riser decides the optic, not the switch brochure.
Ask which FCC equipment authorization and which NRTL file cover the proposed model for a US site. This page does not certify either. A public rule text is a place to learn what to request.
Yes as a procurement question, if the watt sum fits the supply and the VLANs are specified. No as an assumption. Put both device classes in the brief and ask the supplier to mark any port that cannot hold the higher class while the others are loaded.
Document review, then a sample or a photo of the faceplate if you ask for one, then incoming inspection of the serial and the power supply label, then a configuration check if the unit is managed. Commissioning on site is a separate line from the chassis price. Say whether you want it quoted.
A refurbished 12-port PoE unit can cover a legacy install when condition, fan wear, and warranty months are written down. Power-supply age is part of that condition. Keep the refurbished column away from the new-unit column so the watt budget is not the sole difference.
Neighboring port plans are labeled on the inquiry cards. The closet rows go out through the requirement form. Ask the named 12-port datasheet for switching capacity in Gb/s, forwarding rate in Mpps on 64-byte frames, and copper speed as 100BASE-TX or 1000BASE-T. Power over Ethernet stays a class plus a chassis total: 802.3af at 15.4 W, 802.3at at 30 W, or a higher 802.3bt class when a device datasheet requires it. If the uplink is fiber, record wavelength, transmit power in dBm, receiver sensitivity in dBm, optical budget, and insertion loss. A 1U rack unit and a wall-mount box need depth in millimeters. Return loss is a connector row, not a substitute for the watt budget.
Include device classes, the 12-port speed, the uplink, quantity of switches, the US site, and the timing. The form has no attachment control. Describe the map in the requirement field.
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