WS-C3850-12S-S Cisco Catalyst 3850-12S-S 12 Ports Switch

Product Overview

The Cisco WS-C3850-12S-S Catalyst 3850-12S-S is a high-performance, enterprise-grade managed network switch designed for scalable and secure business environments. Built with Cisco’s advanced switching architecture, this model delivers reliable Layer 3 routing, flexible stacking, and intelligent traffic management for modern networks.

General Specifications

• Brand: Cisco Systems, Inc.
• Model / SKU: WS-C3850-12S-S
• Device Category: Managed Layer 3 Switch
• Total Ports: 12 Gigabit Ethernet SFP interfaces
• Form Factor: Desktop or 1U rack-mountable
• Switch Type: Stackable enterprise switch

Network Performance

Engineered for high-throughput networking, this Cisco switch ensures smooth data transmission and optimal performance even in demanding environments.

• Switching Throughput: Up to 68 Gbps
• Forwarding Rate: 68.4 Mpps
• Stacking Bandwidth: 480 Gbps with Cisco StackWise-480
• Jumbo Frame Support: Up to 9198 bytes

Capacity and Scalability

• IPv4 Routing Entries: 24,000 routes
• NetFlow Records: 24,000 entries
• Switched Virtual Interfaces (SVIs): Up to 1,000
• MAC Address Table: 32,000 entries

Routing and Management Capabilities

The Catalyst 3850-12S-S supports a wide range of dynamic routing and management protocols, making it ideal for enterprise and campus networks.

Supported Routing Protocols

• RIP v1 and v2
• EIGRP
• RIPng

Remote Management Protocols

• SNMP v1, v2c, and v3
• RMON v1 and v2
• SSH and Telnet access
• Command Line Interface (CLI)

Advanced Features

This Cisco managed switch is packed with enterprise-level features to enhance security, efficiency, and network visibility.

Switching and Security Features

• VLAN and trunking support
• Auto-negotiation and Auto-MDI/MDIX
• Access Control Lists (ACLs)
• DHCP Snooping and Dynamic ARP Inspection
• IGMP and MLD Snooping
• Port aggregation with PAgP and LACP

Traffic Optimization and Reliability

• Quality of Service (QoS) prioritization
• Rapid Spanning Tree (RSTP) and MSTP
• Per-VLAN Rapid Spanning Tree Plus (PVRST+)
• Layer 3 load balancing
• Energy Efficient Ethernet

Cisco Exclusive Technologies

• Cisco StackWise-480 Technology
• Cisco StackPower Technology
• Flexible NetFlow (FNF)
• Remote SPAN (RSPAN)

Standards and Compliance

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

Power and Reliability

• Power Input: AC 120/230V, 50/60 Hz
• Redundant Power: Optional power redundancy supported

Core Architecture and StackWise-320 Technology

The defining superiority of the WS-C3850-12S-S Catalyst 3850 series lies in its innovative StackWise-320 technology, and the 12S-S model brings this capability to the desktop. This is not merely a stackable switch; it's a system that operates as a single, logical entity.

Unified Stacking Performance

Traditional stackable switches share a single, often limited, stacking bandwidth. The StackWise-320 architecture revolutionizes this by providing a resilient, high-bandwidth stacking ring.

Stacking Bandwidth and Flexibility

Each stack member contributes a massive 160 Gbps of bidirectional bandwidth to the ring, creating a total of 320 Gbps per stack ring. This ensures that inter-unit traffic, critical for control plane communication and data forwarding between switches in the stack, never becomes a bottleneck. You can stack up to nine Catalyst 3850 switches of any port type (copper, SFP, or mixed) together, creating a single, logical switch with hundreds of ports managed from one IP address.

Hitless Stacking and High Availability

The stack operates with a single control plane, simplifying management immensely. Features like hitless failover ensure that if the stack master fails, a new master is elected within sub-seconds without disrupting data forwarding on the stack members. This level of redundancy and high availability is extraordinary for a switch in this form factor and price point.

Hardware Specifications and Physical Design

Meticulously crafted, the WS-C3850-12S-S is built for reliability and silent operation, making it perfect for office spaces.

Port Configuration and Connectivity

The "12S" in its name denotes 12 dedicated SFP (1G) ports. There are no built-in copper RJ-45 ports, emphasizing its role as a fiber aggregation or distribution point.

SFP Flexibility and Uplink Considerations

Each SFP port supports a vast array of Cisco-certified SFP modules, allowing network architects to choose the exact transceiver for the task: multimode fiber (SX) for shorter campus runs, single-mode fiber (LX/LH) for long-distance connections, or even copper SFP (T) for short RJ-45 connections. This allows the switch to serve as a perfect fiber-to-the-desktop unit or a compact distribution switch linking multiple wiring closets via fiber. It also includes 4 x 1G SFP or 4 x 10G SFP+ uplink ports, providing flexible and high-speed connectivity options to core network infrastructure.

Performance and Power Specifications

With a forwarding rate of up to 176 Gbps and a switching capacity of 256 Gbps, the 3850-12S-S handles high-throughput, low-latency traffic with ease. It supports advanced queuing and congestion management mechanisms, ensuring voice, video, and data traffic are prioritized appropriately.

Power over Ethernet (PoE) Capability

It's crucial to note that the 12S-S model, with its all-SFP ports, does not provide Power over Ethernet. SFP ports are data-only. If PoE is a requirement for powering phones, wireless access points, or cameras, the copper-port variants of the Catalyst 3850 (such as the 48-port PoE models) would be necessary, potentially in a stack with the 12S-S.

Software Intelligence: Cisco IOS XE and the IP Base Feature Set

The switch runs on Cisco IOS XE, a modern, modular operating system that provides enhanced stability, serviceability, and programmability. The pre-installed IP Base software image delivers a comprehensive set of features for most enterprise access layer deployments.

Advanced Layer 3 Routing Capabilities

Unlike many access switches limited to Layer 2, the IP Base license on the 3850-12S-S enables static routing and RIP (Routing Information Protocol). This allows the switch to perform inter-VLAN routing locally, improving performance and reducing load on core routers. It supports up to 1000 static routes, making it capable of handling complex internal routing designs.

Security and Identity Management

Security is embedded at every layer. The switch offers a robust suite of features to protect the network infrastructure and control user access.

Network Access Control with 802.1X and Cisco TrustSec

It supports IEEE 802.1X for port-based network access control, ensuring only authorized users and devices can connect. Integrated with Cisco Identity Services Engine (ISE), it can enforce dynamic policies based on who you are, what device you are using, and the device's security posture. Cisco TrustSec technology simplifies access policy enforcement through security group tags (SGTs).

Threat Defense and Visibility

Features like Dynamic ARP Inspection (DAI), IP Source Guard, and DHCP snooping protect against common man-in-the-middle and IP spoofing attacks. Control Plane Policing (CoPP) safeguards the switch's CPU from malicious traffic, ensuring network stability.

Unified Wired and Wireless with Cisco Converged Access

One of the most groundbreaking features of the WS-C3850-12S-S Catalyst 3850 series is its converged access architecture. The switch can integrate a Wireless LAN Controller (WLC) function directly into its operating system.

Benefits of Embedded Wireless Controller

By hosting a wireless controller for up to 50 access points (with the appropriate license), the 3850-12S-S can manage a fleet of Cisco Aironet access points, creating a unified wired and wireless network. This eliminates the need for a separate, physical wireless controller appliance, reducing cost and complexity. It provides a single point of management and policy enforcement for all connected devices, whether they connect via Ethernet or Wi-Fi.

Application Visibility and Control (AVC)

Leveraging Cisco's powerful NetFlow and NBAR2 (Network-Based Application Recognition) technologies, the switch provides deep visibility into the applications flowing across the network. Administrators can identify, classify, and apply policies to thousands of applications, ensuring business-critical software receives priority while potentially limiting bandwidth for recreational applications.

Deployment Scenarios and Use Cases

The unique characteristics of the 3850-12S-S make it ideal for several specific deployment models.

Fiber-Based Workgroup or Departmental Switching

In engineering departments, research labs, or design studios where workstations are equipped with fiber network interface cards (NICs) for high-throughput data transfers (like CAD/CAM files or genomic data), this switch provides a direct, high-performance fiber connection. The low latency and EMI immunity of fiber are critical in these environments.

Compact Distribution/Aggregation Layer Switch

In a small branch office or a single floor of a building, the 3850-12S-S can act as a distribution switch. It can aggregate links from multiple access switches (potentially other 3850s with copper ports) over its fiber uplinks and provide Layer 3 routing between VLANs locally. Its stacking capability allows it to grow as the branch grows.

Backbone for High-Density Wireless Deployments

For environments with a dense deployment of wireless access points, such as schools or conference centers, the 12S-S is an excellent choice. Its SFP ports can connect via fiber to APs located throughout a building, and its embedded wireless controller capability allows it to manage those APs directly, creating a streamlined, high-performance wireless infrastructure.

Secure and Managed Desktop Switch for Sensitive Environments

In settings like financial trading floors, government secure rooms, or industrial control system networks, the need for electromagnetic-secure (TEMPEST) connectivity or simply a physically compact, highly manageable switch is paramount. The all-fiber, silent, and feature-rich 3850-12S-S fits this role perfectly, offering advanced security controls in a discreet package.

Management and Programmability

Managing the Catalyst 3850-12S-S is designed to be intuitive and powerful, catering to both traditional CLI experts and modern automation frameworks.

Traditional and Modern Management Interfaces

It is fully manageable via the industry-standard Cisco IOS CLI, a familiar environment for network professionals. For a graphical interface, it supports Cisco Prime Infrastructure and the embedded device manager web GUI (HTTP/HTTPS) for day-to-day monitoring and configuration. SNMPv1, v2c, and v3 are fully supported for integration into existing network management systems like SolarWinds or LibreNMS.

Embracing Network Programmability

As part of the IOS XE family, this switch is ready for software-defined access (SD-Access) and automation. It supports open APIs including RESTCONF and NETCONF/YANG, allowing network operators to automate provisioning, configuration, and policy deployment using tools like Ansible, Python scripts, or Cisco DNA Center. This future-proofs the investment, aligning it with modern DevOps and NetOps practices.