Juniper power supplies and optics look like small parts, even though the wrong one can take a switch or router offline. A supply with the wrong airflow, wattage or input type may not work in your chassis, while an optic must match both the port and the fiber.
This guide explains how to match replacement power supplies and 25G optics to EX, QFX and MX hardware. It also covers the JPSU-150-AC-AFO, JPSU-920-AC-AFO, JPSU-650W-DC-AFO and JNP-SFP-25G-SR, plus the checks that prevent costly mistakes.
Why Juniper power supplies matter
Many Juniper switches and routers, such as the EX3400, EX4100, QFX5120 and MX204, use field-replaceable power supplies. So when a supply fails, you can swap it without replacing the whole unit. In addition, a second supply adds redundancy and, on PoE switches, more power for devices.
For example, the EX3400-48P has a 740 W PoE budget with one 920 W supply and 1440 W with two. That second supply can decide whether every access point on the floor gets full power.
How to match Juniper power supplies
Wattage
First of all, check the wattage the switch shipped with. The non-PoE EX3400-24T and EX3400-48T use the 150 W JPSU-150-AC-AFO by default. In contrast, the EX3400-48P uses the 920 W JPSU-920-AC-AFO, so a 150 W unit would not cover its PoE load.
AC or DC input
After that, confirm the power feed. Offices and most data centers run on AC, while telecom sites and some carrier racks run on DC. The JPSU-650W-DC-AFO is a 650 W DC supply that Juniper lists for the MX204 router and the EX4650-48Y switch.
Airflow suffix
Then check airflow. AFO means front-to-back airflow, while AFI means back-to-front. Because Juniper does not support mixing airflow directions in one chassis, a replacement supply must match the fans and the other supply.
Juniper power supplies by platform
Here is a quick map of common replacements. For example, the JPSU-150-AC-AFO fits the EX3400-24T and EX3400-48T. The JPSU-920-AC-AFO fits the EX3400-48P, and many sellers also offer it for the EX4100 Series, so confirm the wattage your EX4100 shipped with.
For DC sites, the JPSU-650W-DC-AFO powers the MX204 and the EX4650-48Y. Meanwhile, the AC version of the MX204 uses the JPSU-650W-AC-AO, so order the one that matches your feed.
Matching 25G optics to your ports
Similarly, optics need the same care as power. The JNP-SFP-25G-SR is a 25GbE SFP28 short-reach optic at 850 nm over multimode fiber. It uses a duplex LC connector and reaches up to 100 m on OM4 fiber.
It fits SFP28 ports on switches such as the QFX5120-48Y, EX4650-48Y and EX4100. So it works well for server links inside a rack or between nearby racks. However, longer runs or single-mode fiber need a different optic, so measure the distance and check the fiber type first.
Common mistakes with spares
First of all, do not order by wattage alone. A 650 W supply comes in both AC and DC versions, so check the label before you order. Also, do not assume every optic works in every port, since an SFP28 port and a QSFP28 port take different modules.
Another mistake is keeping no spares at all. Because power supplies and optics fail more often than a chassis, a small shelf of spares cuts downtime. For example, one spare JPSU-920-AC-AFO can cover a whole floor of EX3400-48P switches.
How to find the right part number
The fastest way to confirm a replacement is to read it off the device. On Junos OS, the show chassis hardware command lists each power supply and optic with its part number. So you can copy the exact model instead of guessing from memory.
When the unit has failed, check the label on the supply itself. Then send us that part number along with the switch or router model. That way, we can confirm wattage, input type and airflow before anything ships.
Juniper power supplies and optics part numbers we supply
Silverback supplies every part below in new or used condition. So send us the part number, and get pricing and lead time within one business day.
| Part number | Product | Notes |
|---|---|---|
| JPSU-150-AC-AFO | 150 W AC power supply, front-to-back airflow | Default PSU for EX3400-24T and EX3400-48T |
| JPSU-920-AC-AFO | 920 W AC power supply, front-to-back airflow | Default PSU for EX3400-48P; also offered for EX4100 |
| JPSU-650W-DC-AFO | 650 W DC power supply, front-to-back airflow | DC PSU for MX204 and EX4650-48Y |
| JNP-SFP-25G-SR | 25GBASE-SR SFP28 transceiver | 850 nm, multimode, duplex LC, up to 100 m on OM4 |
New vs used Juniper power supplies
Used power supplies and optics are among the safest used purchases, because they are simple parts and easy to test. As a result, many teams buy used spares and keep new units for fresh builds.
Silverback supplies new and used power supplies and optics, tested before they ship. So ask for new or used condition, and read refurbished vs new enterprise hardware for more on the trade-offs.
Why buy Juniper power supplies from Silverback
Silverback is a trusted supplier of Juniper hardware and a certified HPE Business Partner. We also buy back retired gear and offer certified data destruction under R2v3, ISO 14001 and ISO 45001. See how IT buyback value works for details.
For the switches and routers these parts fit, see the full Juniper product range, our EX access switch guide and our QFX data center guide.
Of course, full specs live on juniper.net. Meanwhile, you can browse our inventory or request pricing for any part above.
Frequently Asked Questions
Can I use a JPSU-150-AC-AFO in an EX3400-48P?
It is not the right choice. The EX3400-48P ships with the 920 W JPSU-920-AC-AFO to power its PoE ports, while the 150 W unit is the default for non-PoE models.
What does AFO mean on a power supply?
AFO means front-to-back airflow. It must match the fans and the other supply, because Juniper does not support mixing airflow directions in one chassis.
Which power supply does the MX204 use?
The MX204 takes the JPSU-650W-AC-AO for AC power or the JPSU-650W-DC-AFO for DC power.
How far does the JNP-SFP-25G-SR reach?
It reaches up to 100 m on OM4 multimode fiber at 850 nm, with a duplex LC connector.
Do you sell used power supplies and optics?
Yes. Silverback supplies new and used power supplies and optics, tested before they ship. Ask for new or used condition when you request a quote.
Get a quote for Juniper power supplies
Whether you need one JPSU-920-AC-AFO or a box of JNP-SFP-25G-SR optics, Silverback can help. Send us your part list with the chassis model, and we will reply with pricing and lead time within one business day.
Then call (888) 391-5211 or get a free quote online. Ask for new or used condition, and we will check wattage, input and airflow for you.
