Did you know that access points can behave differently depending on how much power they are receiving? The addition of a new device drawing the smallest amount of power might be enough to reduce an access point's radio functionality, downgrade the network interface between the AP and switch, or even disable an AP altogether.
PoE (Power over Ethernet) budgeting can impact network performance if under budget, or be a source of waste if overbudgeted. The amount of DC power provided by switches (or switch ports) has been rapidly increasing. The introduction of 90W UPoE+ has opened a whole new world of opportunities. Laptops, cameras, sit-stand desks, LED lighting, even refrigerators and air conditioners are all on the brink of being powered by a network switch.
So, what is PoE? In short, PoE is simply DC power delivered over copper wire. The younger generation reading this article might not be familiar with a plain old telephone (or POT as we used to call them), but if you are, you know that plugging a telephone into a phone outlet generates a dial tone. This was because 48V DC power was being provided by your phone service provider's switching infrastructure. The PoE we're talking about is the same thing provided by our switching infrastructure.
The table above shows the different IEEE standardized “types” of PoE that are currently available. In the past, if a deficient amount of power was being provided, the devices wouldn’t power on. As the products have evolved, the manufacturers are building in a certain level of fault tolerance to make sure some services can still be offered with a lesser amount of power.
Real quick, the PoE standard refers to the port capability, not the switch itself. A C9300-48U switch is a UPoE capable switch, but only comes with an 1100W power supply by default. Even adding another 1100W power supply will only allow PoE+ if all 48 ports are used. With 300W dedicated to other switch services, dual 1100W powers offers a max of 1,800W PoE budget. That's just 37.5W per port if all 48 ports are providing PoE. For full UPoE, only 30 of the 48 ports could provide 60W.
And so back to my opening question. Do you need UPoE? The answer is probably yes. And if not yet, how long before it is?
Flexibility - PoE+ as a standard is waning. There are thousands of network products already requiring more than 30W per port. If we're purchasing hardware, deploying UPoE switches today may save us from prematurely needing a switch upgrade. The cost increase from PoE+ to UPoE is small, and we'll be better positioned to handle future requirements which seem almost to be a certainty.
Supportability - We don't want unusual and sporadic network issues, nor any device that isn't fully functioning. All APs are coming from the manufacturers with varying behavioral differences determined by how much power is being provided. Some combination of reduced radios, reduced spatial streams, LAN1 and/or LAN2 ports speed reduced or disabled, transmit power reduced, USB ports disabled. Aruba already has APs that require UPoE+ (90W) to fully function. Otherwise, UPoE (60W) is the only standard that will light up every Cisco, Juniper, or Meraki AP without any restrictions. Aruba has a feature known as Intelligent Power Management (IPM) which allows us to program how our AP might behave without full power, but why? We're trying to avoid bottlenecks, not create them. Why not purchase a lower-end AP and save money?
The same sentiment is true with Multi-Gig or mGig ports. All enterprise-grade APs manufactured after 2024 has network interfaces of at least 2.5G, so why would we plug them into a 1G switch?
Did you know that Edgeium has used C9300 switches with Multi-Gig ports and UPoE at a lower cost than the C9300-48P?
So, what kind of behavioral differences can we expect? Radios will be downgraded or disabled, network interfaces will be downgraded or disabled, USB ports disabled, PoE-PD can be downgraded or disabled, etc. Lets take a quick look at the different OEMs.
Cisco:
Aruba:
Juniper:
Meraki:
Thank you for reading!