WS-C3850-24S-E Cisco Catalyst Ethernet Switch 24 Ports

Product Outline: Cisco Catalyst WS-C3850-24S-E Switch

The Cisco Catalyst WS-C3850-24S-E is a high-performance, enterprise-grade Layer 3 managed switch designed to deliver reliability, scalability, and advanced network control. Built for modern business networks, this Cisco Catalyst switch provides robust routing, enhanced security, and seamless stacking capabilities for growing infrastructures.

General Specifications

Manufacturer & Model Details

• Brand: Cisco
• Model Number: WS-C3850-24S-E
• Device Type: Managed Layer 3 Ethernet Switch
• Form Factor: Desktop or Rack-Mountable (1U)
• Stackable: Yes

Port Configuration

• 24 x Gigabit Ethernet SFP ports
• Optimized for fiber-based network deployments
• Ideal for enterprise core and access layer switching

Performance and Capacity

Switching & Forwarding Performance

• Switching Capacity: 92 Gbps
• Forwarding Rate: 68.4 Mpps
• Stacking Bandwidth: 480 Gbps with Cisco StackWise-480

Network Scalability

• 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

Advanced Routing and Protocol

Layer 3 Routing Protocols

• BGP-4
• IS-IS
• RIP v1 & v2
• EIGRP (IPv4 and IPv6)
• OSPFv3
• PIM-SM and PIM-SSM
• RIPng

Key Features and Network Enhancements

Security, Control, and Optimization

• VLAN and trunking support
• Access Control Lists (ACLs)
• DHCP Snooping and Dynamic ARP Inspection (DAI)
• IGMP and MLD Snooping
• IPv4 and IPv6 compatibility
• Quality of Service (QoS) for traffic prioritization
• RADIUS authentication support
• VRF-Lite for network segmentation

Spanning Tree and Link Management

• Rapid Spanning Tree Protocol (RSTP)
• Multiple Spanning Tree Protocol (MSTP)
• Per-VLAN Rapid Spanning Tree Plus (PVRST+)
• STP Root Guard and UDLD

High Availability and Efficiency

• Link Aggregation Control Protocol (LACP)
• Port Aggregation Protocol (PAgP)
• Layer 3 Load Balancing
• Energy Efficient Ethernet
• Cisco StackPower Technology
• Flexible NetFlow (FNF)

Compliance and Industry Standards

Supported IEEE Standards

• IEEE 802.3, 802.3u, 802.3z, 802.3ab
• IEEE 802.1D, 802.1Q, 802.1P
• IEEE 802.3x and 802.3ad (LACP)
• IEEE 802.1W, 802.1X, 802.1S

Core Architecture and Hardware Specifications

At its heart, the WS-C3850-24S-E is built to handle high-density, high-performance networking environments where reliability and speed are non-negotiable.

Port Configuration and Uplink Capabilities

This model is equipped with 24 dedicated Gigabit Ethernet SFP ports, providing maximum flexibility for fiber connectivity. These ports support a wide range of SFP modules (GLC-SX-MMD, GLC-LH-SMD, etc.) for connectivity over multimode or single-mode fiber, allowing for tailored reach and media options. The "S" designation signifies an all-fiber front panel, ideal for backbone connections, server access, or environments requiring EMI immunity and longer cable runs. For uplink expansion, the switch includes four built-in 1G/10G SFP+ uplink ports, offering high-speed aggregation and future-proofing network capacity.

Performance and Switching Fabric

The switch boasts a robust forwarding rate of 176 Gbps and a packet forwarding performance of up to 240 Mpps. This is powered by a scalable switching fabric that can be multiplied through stacking. The device supports the Cisco StackWise-480 technology, allowing you to logically interconnect up to nine physical switches to operate as a single, highly resilient logical unit with a collective stacking bandwidth of 480 Gbps.

Key Hardware Components:

CPU & Memory: Advanced multi-core processor with ample DRAM for control plane functions and TCAM for high-speed ACL and routing table lookups.
Power Supplies: Supports modular, redundant power supplies (such as the PS1K12A) for critical deployments requiring high availability.
Cooling: Designed with redundant, variable-speed fans for efficient and quiet operation in wiring closets.

Unified Access and Software Capabilities

The "E" in the model number denotes the IP Base feature set, which includes advanced Layer 3 routing protocols. However, the true differentiator of the Catalyst 3850 platform is its unified software architecture.

Cisco IOS XE and Feature Sets

The switch runs on Cisco IOS XE Software, a modern, Linux-based operating system that provides enhanced stability, serviceability, and programmability. The IP Base image supports essential enterprise features:

Layer 3 Routing: Static routing, RIP, EIGRP Stub, and OSPF for basic routing.
Advanced QoS: Granular classification, marking, policing, and queuing to ensure optimal performance for voice, video, and data.
Security: Comprehensive ACLs (standard, extended, VLAN-based), DHCP snooping, Dynamic ARP Inspection (DAI), and IP Source Guard.
High Availability: Features like Hot Standby Router Protocol (HSRP), StackWise for sub-second failover, and optional redundant power.

Deployment Scenarios and Use Cases

The Cisco Catalyst WS-C3850-24S-E is versatile and suited for a range of demanding network roles.

Enterprise Building/Campus Access Layer

Its primary role is as a high-performance access switch. The 24 SFP ports make it perfect for connecting to other switches in a fiber-rich campus distribution layer or to servicedirectly via fiber NICs. Its Layer 3 capabilities allow for routing at the edge, segmenting departments or floors into different VLANs while maintaining inter-VLAN routing locally.

Example Configuration:

Deploying multiple WS-C3850-24S-E switches in a StackWise configuration across a campus building. This creates a single management point, simplifies spanning-tree topology, and allows for inter-switch link aggregation across the stack for unparalleled resilience.

Data Center Server Access

In mid-sized data centers or server rooms, the switch's high throughput, 10G uplinks, and low latency make it an excellent Top-of-Rack (ToR) switch. The all-fiber ports are ideal for connecting to blade servers or storage arrays equipped with SFP network interfaces.

Medium to Large Business Backbone

With its powerful routing and high-speed uplinks, the switch can effectively serve as a distribution or collapsed core switch for medium-sized organizations, aggregating traffic from multiple access layer switches and routing between subnets.

Advanced Features and Network Management

Beyond basic switching and routing, the Catalyst 3850 is packed with features for optimized control and visibility.

Energy Efficiency and PoE Capabilities (Note on Model Variant)

It's important to note that the WS-C3850-24S-E is an SFP-only model and does not provide Power over Ethernet (PoE). For locations requiring PoE to power devices like IP phones, wireless access points, or cameras, the PoE-capable variants (like the WS-C3850-24T-E or 48P models) should be considered. However, this model still incorporates Cisco EnergyWise technology for monitoring and managing power usage of connected devices and the switch itself.

Network Virtualization and Segmentation

The switch supports Cisco TrustSec® technology, which uses software-defined segmentation to classify and enforce security policies based on user roles, not just IP addresses. This simplifies ACL management and enhances security posture.

Flexible NetFlow for Enhanced Visibility

Integrated Flexible NetFlow (FNF) allows for detailed monitoring of network traffic patterns, providing data for capacity planning, security analysis, and billing. It enables the identification of applications and users consuming the most bandwidth.

Management and Programmability

Administrators can manage the switch via multiple avenues:

CLI: The traditional, powerful Cisco IOS command-line interface.
Cisco Prime™ Infrastructure: For holistic, network-wide provisioning, monitoring, and troubleshooting.
Cisco DNA Center: For intent-based networking, automating day-0 to day-N operations, and applying policy across the entire network fabric.
APIs: Support for RESTCONF/NETCONF YANG models, enabling automation and integration with DevOps tools like Ansible or Python scripts.

Comparison with Successor Platforms

While the Catalyst 3850 is a mature and highly capable platform, it is part of Cisco's earlier generation of unified access switches. Its natural successor is the Cisco Catalyst 9300 Series, which offers higher port densities, more advanced security (encrypted traffic analytics), and is the flagship platform for Cisco's Software-Defined Access (SD-Access) solution. The 3850 remains an excellent, cost-effective choice for robust, proven wired/wireless convergence, especially in environments not immediately transitioning to intent-based networking.