WS-C3850-24U-E Cisco Catalyst Ethernet Switch

Product Summary

The Cisco WS-C3850-24U-E Catalyst 3850 is a high-performance, enterprise-grade managed network switch designed for modern business environments. Built for scalability, reliability, and advanced Layer 3 networking, this model delivers powerful switching, enhanced security, and intelligent traffic management for growing networks.

General Specifications

• Brand: Cisco Systems
• Model Number: WS-C3850-24U-E
• Network Device Type: Managed Layer 3 Ethernet Switch
• Total Ports: 24 Gigabit Ethernet Ports
• Form Factor: Desktop or Rack-mountable (1U)
• Stackable Design: Yes

Ethernet & Connectivity

This Cisco Catalyst switch supports Gigabit Ethernet connectivity with advanced uplink flexibility, making it ideal for campus networks, branch offices, and enterprise deployments.

• 24 x 10/100/1000 Mbps Ethernet ports
• Automatic MDI/MDI-X detection
• Auto-negotiation for optimal speed and duplex

Power over Ethernet Capabilities

Universal Power over Ethernet (UPOE)

Designed to power next-generation devices, this switch provides Universal Power over Ethernet, reducing the need for additional power sources.

• PoE Technology: UPOE
• Total PoE Power Budget: 800 Watts
• Supports IP phones, wireless access points, cameras, and IoT devices

Performance & Switching Capacity

High-Speed Data Handling

• Switching Capacity: 88 Gbps
• Stacking Bandwidth: 480 Gbps
• Optimized for low latency and high throughput

Stacking Technologies

• Cisco StackWise-480 Technology
• Cisco StackPower Technology
• Centralized management across stacked switches

Routing & Network Capacity

Advanced Layer 3 Features

• IPv4 Routing Entries: Up to 24,000
• NetFlow Entries: 24,000
• Switched Virtual Interfaces (SVIs): 1,000
• MAC Address Table: 32,000 entries
• Jumbo Frame Support: Up to 9,198 bytes

Supported Routing Protocols

• BGP-4, IS-IS, RIP v1/v2
• EIGRP and EIGRP for IPv6
• OSPFv3
• PIM-SM, PIM-SSM, RIPng

Security & Network Management

Remote Management Interfaces

• SNMP v1, v2c, and v3
• RMON 1 and 2
• SSH, Telnet, and CLI access

Integrated Security Features

• Access Control Lists (ACL)
• Dynamic ARP Inspection (DAI)
• DHCP Snooping
• RADIUS authentication support
• IPv4 and IPv6 compatibility

Traffic Optimization & Monitoring

• Quality of Service (QoS)
• Flexible NetFlow (FNF)
• Remote SPAN (RSPAN)
• Layer 3 Load Balancing

Network Reliability & Switching Protocols

• VLAN and Trunking Support
• Rapid Spanning Tree Protocol (RSTP)
• Multiple Spanning Tree Protocol (MSTP)
• Rapid Per-VLAN Spanning Tree Plus (PVST+)
• Link Aggregation Control Protocol (LACP)
• Port Aggregation Protocol (PAgP)

Energy Efficiency & Compliance

Standards & Certifications

• IEEE 802.3, 802.3u, 802.3ab, 802.3z
• IEEE 802.1D, 802.1Q, 802.1P
• IEEE 802.1W, 802.1X, 802.1S
• IEEE 802.3af and 802.3at

Power Specifications

• Input Voltage: AC 120 / 230 V
• Frequency: 50/60 Hz
• Optional Power Redundancy
• Energy Efficient Ethernet support

Core Innovation: The Convergence of Wired and Wireless

Before the Catalyst 3850, managing wired and wireless networks often required separate hardware, software, and operational teams. The 3850 eliminated this siloed approach by integrating an embedded wireless LAN controller directly into the switch stack. This allows the switch to natively manage up to 50 Cisco Aironet access points, providing a single point of configuration, policy management, and troubleshooting for all connected devices, regardless of their access medium. This convergence simplifies the network hierarchy, reduces total cost of ownership, and ensures that security and quality-of-service policies are uniformly applied from the core to the edge, whether a user connects via an Ethernet cable or a Wi-Fi signal.

Deep Dive: Cisco WS-C3850-24U-E Model Specifications

The Cisco WS-C3850-24U-E Catalyst 3850 is a specific, feature-rich configuration within the series. The model number breaks down as follows: WS-C3850 denotes the series, 24U indicates 24 Ethernet ports with Universal PoE capability, and the suffix -E signifies the enhanced feature set software license. This combination makes it one of the most versatile and powerful fixed-configuration access switches for demanding environments.

Hardware Architecture and Performance

Built on a powerful multi-core CPU architecture, the 3850-24U-E is designed for high-performance forwarding and intelligent services. It features a generous onboard buffer memory to handle traffic bursts common in converged networks. The switch's stacking capabilities are a key performance differentiator.

StackWise-480 Technology

The switch supports Cisco StackWise-480 technology, allowing you to interconnect up to nine individual Catalyst 3850 switches to operate as a single, logical entity. The stacking ring provides an aggregate 480 Gbps of backplane bandwidth, creating a resilient, high-throughput system for uplinks and inter-unit communication. This simplifies management (one IP address for the entire stack), enhances redundancy (automatic failover if a stack member fails), and enables flexible scaling of port density.

Port Configuration: Versatility and Power

The "24U" in the model name is critical. It provides:

24 x RJ-45 Ethernet Ports: All 24 are Universal PoE/PoE+ capable.
4 x 1G SFP Uplink Ports: Dedicated ports for high-speed fiber or copper uplinks to the network core.

Understanding Universal PoE (UPoE)

This is a standout feature. While standard PoE (802.3af) provides up to 15.4W and PoE+ (802.3at) up to 30W per port, Cisco's UPoE (a pre-standard implementation of 802.3bt) can deliver a groundbreaking up to 60 watts of power over a standard Ethernet cable. This future-proofs the switch for powering a new generation of devices beyond phones and access points, such as:

High-performance PTZ video conferencing camerasThin clients and desktop computers
Digital signage and kiosks
Building automation and IoT sensors with higher power needs

The total power budget is substantial, allowing administrators to fully utilize the UPoE capability across multiple ports simultaneously.

Software and Feature Set: The "-E" License Advantage

The "-E" designation indicates the pre-installed IP Services feature set license. This is the most comprehensive software tier for the Catalyst 3850, unlocking advanced Layer 3 routing, security, and analytics capabilities.

Advanced Layer 3 Routing

Unlike basic Layer 2 access switches, the 3850-24U-E operates as a full-featured router. It supports static routing, RIP, OSPF, EIGRP, and BGP for IPv4 and IPv6. This enables routed access designs, where the switch acts as the default gateway for connected endpoints, collapsing the traditional distribution layer and creating a flatter, more efficient network architecture with fewer hops and reduced latency.

Cisco IOS XE: A Robust Operating System

The switch runs Cisco IOS XE, providing a consistent operational experience with Cisco routers. It offers features like:

Programmability: APIs (RESTCONF, NETCONF) and support for Python scripting for automation and integration with modern IT tools.
High Availability: In-Service Software Upgrade (ISSU) allows for software updates with minimal downtime.
Resiliency: Graceful restart protocols for OSPF, EIGRP, and BGP.

Key Technologies and Use Case Applications

The combination of hardware and software in the WS-C3850-24U-E makes it ideal for a wide array of demanding deployment scenarios.

Network Foundation: Security and QoS

Cisco TrustSec and Security Hardening

The switch provides comprehensive security. Cisco TrustSec uses Software-Defined Access (SDA)-like principles to enforce policy based on user or device identity, not just IP address. It includes:

802.1X Authentication: For both wired and wireless clients.
MACsec Encryption: Hardware-based 256-bit encryption on every port for secure, hop-by-hop communications.
ACI Integration: Can operate as an Application Policy Infrastructure Controller (APIC) leaf switch in a Cisco ACI fabric.
Advanced ACLs, DHCP snooping, IP Source Guard, and Dynamic ARP Inspection to prevent attacks.

Advanced Quality of Service (QoS)

In a converged network carrying voice, video, data, and IoT traffic, QoS is essential. The 3850 provides granular, hardware-based classification, marking, policing, and scheduling. It can recognize thousands of applications via Network Based Application Recognition (NBAR2), allowing policies to prioritize business-critical applications (like VoIP or SAP) while limiting bandwidth for recreational traffic.

Cisco Application Visibility and Control (AVC)

This powerful analytics feature uses NBAR2 and Flexible NetFlow to provide deep visibility into application usage on the network. Administrators can create detailed reports on which applications are consuming bandwidth, who is using them, and their performance metrics. This data is crucial for capacity planning, troubleshooting, and enforcing acceptable use policies.

Ideal Deployment Environments

Enterprise Campus and Branch Offices

As a primary access layer switch in large campuses or as a consolidated stack in a branch office, the 3850-24U-E provides the perfect blend of port density, PoE power, routing intelligence, and wireless convergence. It can serve as the sole networking device in a smaller branch, handling all wired, wireless, and WAN routing needs.

Modern Workspaces and IoT-Ready Buildings

With UPoE, the switch is ideal for smart buildings and modern offices deploying extensive digital signage, video conferencing systems, and IoT sensors. The ability to power and network these diverse devices from a single, centrally managed switch infrastructure drastically simplifies deployment and operations.

Medium to Large Enterprise Access Layer

For companies undergoing network modernization, the 3850 serves as a strategic upgrade from older Catalyst 3750X or 2960 series switches. Its StackWise capability allows for easy growth, while the advanced feature set supports initiatives like network segmentation, IPv6 deployment, and software-defined access.

Considerations for Deployment and Operation

Successfully integrating the Catalyst 3850-24U-E requires understanding its operational context.

Stacking and Physical Design

When planning a stack, use dedicated stacking modules and cables. Physically arrange stack members across different power circuits or racks for enhanced redundancy. The active switch in the stack (the "master") controls all members; planning for master election priorities is a key design step.

Power and Cooling Requirements

The switch typically ships with one or two hot-swappable power supplies. For full UPoE utilization across all ports, redundant power supplies and adequate AC circuit capacity are mandatory. Ensure the installation site meets the specified airflow and thermal guidelines, as a fully loaded switch generates significant heat.

Migration and Interoperability

The Catalyst 3850 interoperates seamlessly with other Cisco switches and routers. For networks with existing Cisco Wireless LAN Controllers (WLCs), the 3850's embedded wireless controller can co-exist or be part of a migration plan to a converged access architecture.

Legacy and Transition in the Cisco Portfolio

While the Catalyst 3850 has been a workhorse, it is important to note its position in Cisco's evolving portfolio. It has been succeeded by the Catalyst 9000 series (e.g., Catalyst 9300, 9400, 9500), which are built on a modern, programmable ASIC architecture and are designed for intent-based networking with Cisco DNA Center.

When to Choose the Catalyst 3850-24U-E

This model remains an excellent choice for:

Cost-Effective Upgrades: Organizations seeking advanced features like UPoE and converged access at a potentially lower initial cost than the latest generation.
Stable, Proven Technology: Environments that value the maturity and reliability of the IOS XE code base on this hardware platform.
Specific Feature Needs: Projects with an immediate requirement for full UPoE or embedded wireless controller functionality in a stackable form factor.

The Evolution to Catalyst 9000 and DNA

The Catalyst 9000 series offers higher performance, greater security with Encrypted Traffic Analytics (ETA), and full integration with Cisco's Software-Defined Access (SD-Access) solution through Cisco DNA Center. For greenfield deployments or organizations committed to a full intent-based networking strategy, the Catalyst 9300 would be the modern equivalent. However, the Catalyst 3850-24U-E continues to be a highly capable, robust, and viable solution for a vast range of enterprise networking needs, representing the pinnacle of the pre-DNA, converged access era.