The HP 4500-48-PoE Switch (JE048A) was formerly sold as the 3Com (3CR17572-91) 4500 PWR 50-port
The JE090A and 3CR17251-91 are the same product
See Hp cross refernece look up:
3COM corporation was aquired by HP on November 11, 2009
The 3Com / HP Switch 5500G-EI 48-Port is a premium stackable 10/100/1000 switch with Enhanced Image (EI) software for businesses running the most demanding network applications requiring the highest “five 9s” network uptime.
3COM 3C17251-91 has the 3C17267 power supply installed.
48 ports operate at 10/100/1000; four of these ports are dual-purposed with four SFP-based Gigabit ports.
Expansion module slot offers additional Gigabit or 10-Gigabit Ethernet connectivity.
Stack Port Yes
Total Number of Network Ports 48
Number of Network (RJ-45) Ports 48
Port/Expansion Slot Details 48 x Gigabit Ethernet Network
Port/Expansion Slot Details 4 x Gigabit Ethernet Expansion Slot
Media & Performance
Media Type Supported Twisted Pair
Ethernet Technology Gigabit Ethernet
Network Technology 10/100/1000Base-T
Number of Total Expansion Slots 4
Expansion Slot Type SFP
Network & Communication
Layer Supported 4
Management & Protocols
Input Voltage 110 V AC
Input Voltage 220 V AC
Form Factor Desktop
Form Factor Rack-mountable
Limited lifetime Warranty with HP