WS-C3750X-24T-S Cisco Catalyst Switch 24 Port Layer 3 Rack-mountable Module

In-Depth Focus: Cisco WS-C3750X-24T-S 24-Port Switch

The Cisco WS-C3750X-24T-S is a specific configuration within the 3750-X family that has seen widespread deployment. Its part number decodes its key attributes: WS-C (Cisco Switch), 3750X (Series), 24T (24 x 10/100/1000BASE-T RJ-45 ports), and S (Standard LAN Base software image). This model is the workhorse of the line, providing a dense array of Gigabit Ethernet copper ports for connecting everything from desktop PCs and IP phones to wireless access points and servers.

Hardware Architecture and Physical Specifications

This 1 rack unit (1RU) switch is built with a robust, metal chassis designed for installation in standard 19-inch equipment racks. Its defining hardware characteristic is its modularity.

Modular Power Supply & Fan Tray

Every Catalyst 3750-X switch, including the 24T-S, features a field-replaceable power supply bay at the rear. It can accept either a standard AC power supply or, critically, a redundant AC or DC power supply for high-availability deployments. Similarly, the fan tray is modular and hot-swappable, allowing for maintenance without network downtime. This design dramatically improves mean time to repair (MTTR) and is a key differentiator from fixed-configuration switches.

Network Module Uplink Bay

On the rear of the switch, next to the power supply, is a slot for optional uplink modules. While the base WS-C3750X-24T-S comes with its 24 built-in Gigabit Ethernet ports, this slot allows for significant uplink flexibility.

Optional Uplink Module Examples:

C3KX-NM-1G: Provides two additional Small Form-Factor Pluggable (SFP) slots for Gigabit fiber (e.g., 1000BASE-SX/LX) or copper uplinks.
C3KX-NM-10G: Provides two 10 Gigabit Ethernet SFP+ ports (e.g., for 10GBASE-SR or LR connections), enabling high-speed aggregation to the network core or storage.

This modularity future-proofs the investment, allowing network bandwidth to be upgraded as needs evolve without replacing the entire switch.

Software & Feature Set: LAN Base Image

The "S" in the model number denotes the LAN Base software image. This is a foundational, yet powerful, software tier that provides essential enterprise features.

Layer 3 Routing Capabilities

The LAN Base image supports static routing and Routing Information Protocol (RIP) for IPv4 and IPv6. This allows the switch to perform inter-VLAN routing, effectively collapsing the traditional router-on-a-stick model and improving latency for traffic moving between VLANs locally.

Advanced Switching Features

It includes a full suite of IEEE protocols: Spanning Tree Protocol (STP, RSTP, MSTP) for loop prevention, VLAN Trunking Protocol (VTP) for VLAN management simplification, and Link Aggregation Control Protocol (LACP) for bundling multiple ports into a single logical EtherChannel for increased bandwidth and redundancy.

Security and Management

Security features are robust, including 802.1X port-based authentication for network access control (NAC), Access Control Lists (ACLs) for filtering traffic, and SSH/SNMPv3 for secure management. It also supports advanced QoS for prioritizing latency-sensitive traffic like voice and video.

Typical Deployment Scenarios and Use Cases

The versatility of the Cisco WS-C3750X-24T-S makes it suitable for a wide array of networking environments. Its blend of density, Layer 3 intelligence, and reliability addresses core business connectivity needs.

Enterprise Office Access Layer

This is the most common deployment. The switch is deployed in wiring closets, providing Gigabit to the desktop for employees. Its PoE+ capability (on the PoE model variant, the 24P-S) can power IP phones, wireless access points, and video surveillance cameras. The Layer 3 functionality allows for local routing between departmental VLANs (e.g., Engineering, Finance, HR) without traversing the core.

Branch Office Backbone

In a regional or branch office, a stack of 3750-X switches can serve as the entire network foundation, combining user access, server connectivity, and WAN/router interconnection. The optional 10G uplinks can connect to a local server or storage device, while the robust routing and security features ensure the branch is secure and efficiently connected to the corporate headquarters.

Data Center Server Access (Top-of-Rack)

While later series like the Nexus line are purpose-built for data centers, the 3750-X is often deployed at the top of server racks in small to mid-sized data centers or for specific application tiers. Its low latency, high throughput, and 10G uplink options provide excellent connectivity for physical and virtual servers.

MDF/IDF Aggregation

The switch can act as an aggregation point for multiple downstream switches from various floors or departments, consolidating traffic and applying policy before handing off to the network core via high-speed fiber uplinks.

Software Image Hierarchy and Upgrades

The Catalyst 3750-X series historically operated with three main software images: LAN Base (S), IP Base, and IP Services. The WS-C3750X-24T-S ships with LAN Base. It is possible to upgrade the software license to a more feature-rich image (like IP Services for dynamic routing protocols like OSPF and EIGRP) by purchasing a separate software license from Cisco, though this typically requires a support contract. It's vital to verify the current installed image when procuring equipment.

Stacking Technology: Cisco StackWise Plus

A hallmark of this category is the StackWise Plus technology. Special stacking cables and modules (like the STACK-T1-50CM cable) are used to interconnect multiple 3750-X switches into a stack. This creates a single management point and a 64 Gbps bidirectional stacking ring. Stack members can be added or removed with minimal disruption, offering linear scalability.

Comparing to Successor Models (Catalyst 9200/9300)

While the 3750-X is a mature platform, comparing it to its successors contextualizes its value. The Catalyst 9300 series offers:

Higher performance with UADP ASICs.Modern software based on Cisco IOS XE, enabling programmability with APIs.
DNA Center compatibility for intent-based networking.
Official Cisco support and warranty for new deployments.

The choice between a new 3750-X from the secondary market and a new 9300 often comes down to budget, feature requirements, and the need for official support versus the proven reliability and lower cost of a legacy, yet capable, platform like the 3750-X.