What is the switching performance?

Switch fabric speed is 3.8 Gbps with 4.67 million pps throughput, 10,000 MAC address table entries, and latency under 10 µs (LIFO). As a store-and-forward switch, it provides low-latency performance for high-speed workgroup networking.

How is the switch managed?

Management via web interface, console interface, and SNMP. Supports RMON (groups 2,3,9), with protocols including VLAN (up to 30 port-based with 802.1Q tagging), CoS 802.1p, and protocol filtering for traffic control.

What are the environmental specs?

Operating temperature range is 32°F to 131°F (0°C to 55°C). Form factor is desktop/rack-mountable chassis with single fixed internal power supply and optional redundant supply for reliability.

What expansion options are available?

5 universal slots accept HP ProCurve modules like Gigabit-LX (J4114A) or 10Base-FL. Preinstalled 10/100 modules in first 5 slots; supports distances up to 500m on 50 µm cable for fiber modules.

What LEDs are on the switch?

Status LEDs for power, fault, self-test, engine fail, and per-port link/activity/mode. Console port and mode select button with indicators aid troubleshooting and configuration.

J4121A - HP Switch 4000m 40 RJ-45 auto-sensing 10/100 ports (IEEE 802.3 Type 10Base-T); 5 open module slots Switch

Name: J4121A - HP Switch 4000m 40 RJ-45 auto-sensing 10/100 ports (IEEE 802.3 Type 10Base-T); 5 open module slots Switch
Brand: HP
SKU: J4121A
Price: 185 USD
Availability: InStock

J4121A - HP Switch 4000m 40 RJ-45 auto-sensing 10/100 ports (IEEE 802.3 Type 10Base-T); 5 open module slots Switch | US IT Hardware

Product overview

The HP ProCurve Switch 4000m (J4121A) is a managed modular Ethernet switch designed for enterprise environments requiring scalable networking. It features 40 RJ-45 auto-sensing 10/100 ports and 5 open module slots for flexible expansion with Gigabit uplinks or other modules. With a switching capacity of 3.8 Gbps and throughput of 4.67 million pps, it supports a MAC address table of 10,000 entries and latency under 10 µs (LIFO). Management options include web interface, console, and SNMP, with protocols like VLAN support (up to 30 port-based VLANs), 802.1p CoS, and protocol filtering. The desktop/rack-mountable chassis operates from 32°F to 131°F (0°C to 55°C) using a single fixed internal power supply. Status LEDs indicate power, status, and port activity. Ideal for high-performance workgroups, it enables low-cost migration to 10/100 switching while building high-availability networks.

40x10/100 ports + 5 module slots for scalable connectivity
3.8 Gbps switching, 4.67 Mpps throughput, <10 µs latency
10,000 MAC entries for large-scale enterprise networks
Up to 30 VLANs, 802.1Q, CoS 802.1p prioritization
Web, console, SNMP management interfaces
Rack-mountable, 0-55°C operation, single power supply

Expedited and overnight shipping options are available at checkout, priced by destination and service.
Purchase orders accepted from qualified institutions.
Refunds within 14 days and replacements within 30 days of delivery with an RMA (25% restocking fee on customer-initiated returns), and every part carries our Standard 30-Day Warranty - see our return policy or contact US IT Hardware.

Featuring

Manufacturer part #	J4121A
Brand	HP
Condition	Refurbished
RMON	2 (history), 3 (alarm), 9 (events); XRMON
Model	Switch 4000m
Status LEDs	LED indicators for power, status, and port activity
Product Line	ProCurve
Product Type	Managed Modular Ethernet Switch
Supported Protocols	VLAN support and 802.1Q tagging (up to 30 port-based VLANs); Class of Service (CoS) 802.1p tagging; Protocol filtering
Management Interface	Web interface; Console interface; SNMP support

Compatible systems

No specific system or OS compatibility listed in sources; managed via web/console/SNMP.

Best for

Workgroup Networking
Builds high-performance switched workgroups with 40 auto-sensing 10/100 ports and 3.8 Gbps switching capacity, delivering low latency under 10 µs for high-speed networking.
VLAN Segmentation
Supports up to 30 port-based VLANs with 802.1Q tagging and protocol filtering, enabling secure traffic segmentation in enterprise environments.
Scalable Expansion
5 open module slots allow addition of Gigabit uplinks or other modules, supporting MAC table of 10,000 entries for growing networks.
Managed Environments
Web, console, and SNMP management interfaces provide comprehensive control, with CoS 802.1p for prioritized traffic handling.

Latency	<10 µs (LIFO)
Throughput	4.67 million pps
MAC Address Table	10,000 entries
Switching Capacity	Switch fabric speed: 3.8 Gbps

Max Wattage	250 W (maximum)
Power Supplies	Single fixed internal power supply

Depth	20.3 in.
Width	14.1 in.
Height	17.5 in.
Weight	35.0 lb. (15.88 kg)
Form Factor	Desktop/Rack-mountable chassis

HP Switch 4000m 40 RJ-45 auto-sensing 10/100 ports (IEEE 802.3 Type 10Base-T); 5 open module slots Switch

Product overview

Featuring

Compatible systems

Best for

Frequently asked questions

Details

Shipping, warranty & returns

Customer reviews

Network & Communication

Power Consumption

Physical Characteristics

Environmental

Interface/Ports

Console Port	RJ-45
Ethernet Ports	40 RJ-45 auto-sensing 10/100 ports (IEEE 802.3 Type 10Base-T); 5 open module slots
Expansion Slots	5 open module slots