WS-X6248-RJ-45 Cisco Ethernet Switching Module 48 Ports

Detailed Specifications of the Cisco WS-X6248-RJ-45 Module

The Cisco WS-X6248-RJ-45 is a 48-port 10BASE-T/100BASE-TX Ethernet switching module. It represents a specific era of network design, optimized for delivering desktop connectivity and server access in a reliable, manageable form factor.

Understanding the Uplink Ports

The integrated 100BASE-FX uplinks are a distinguishing feature. They eliminate the need for external transceivers or separate uplink modules, providing a built-in path for aggregating traffic from the 48 user ports to network distribution layers. The MT-RJ fiber connector is a small-form-factor interface common in its deployment period.

Performance and Switching Architecture

This module operates as a Layer 2 switching module. All switching decisions are made at the data link layer (MAC address) based on the forwarding tables managed by the chassis supervisor.

Advanced Features and Network Benefits

Beyond basic connectivity, the WS-X6248-RJ-45 module, when paired with a capable Supervisor Engine, unlocks a suite of enterprise-class networking features essential for building secure, controlled, and efficient networks.

Comprehensive VLAN Support and Management

The module fully supports IEEE 802.1Q VLAN trunking and VLAN Trunking Protocol (VTP), allowing for logical network segmentation across the chassis.

Key VLAN Capabilities

Port-Based VLANs: Assign each of the 48 ports to specific VLANs for broadcast isolation.
802.1Q Trunking: Utilize the uplink ports or any user port to carry multiple VLANs to other switches or routers.
VLAN Query Protocol (VQP): Support for dynamic VLAN assignment.
Private VLAN (PVLAN) Support: When configured on the supervisor, provides further isolation within a primary VLAN.

Quality of Service (QoS) for Traffic Prioritization

The module includes robust QoS features to prioritize latency-sensitive traffic like voice and video over standard data traffic.

QoS Mechanisms Implemented

Classification and Marking: Can trust or classify traffic based on IP Precedence, DSCP, or 802.1p CoS bits.
Policing and Shaping: Supports committed access rate (CAR) and traffic shaping to manage bandwidth.
Congestion Management: Uses weighted round robin (WRR) and strict priority queuing on egress ports.

Voice over IP (VoIP) Readiness

A critical use case. The module can be configured to automatically trust and prioritize traffic from Cisco IP Phones (via CDP), ensuring high voice quality. It can also provide inline power (via a separate power module, WS-X6248A-TEL) for early-generation IP phones.

Security and Access Control Features

Network security is enforced at the port level through various mechanisms.

Port Security Suite

MAC-Based Port Security: Restricts port access to specific MAC addresses, preventing unauthorized device attachment.
802.1X Authentication: Provides network access control using RADIUS servers for user authentication.
Dynamic ARP Inspection (DAI) & IP Source Guard: When supported by the supervisor, these features prevent ARP spoofing and IP address theft.
ACL Support: Standard and extended IP ACLs can be applied to filter traffic on the module's ports.

Primary Use Cases and Deployment Scenarios

The WS-X6248-RJ-45 module was engineered for specific network roles, predominantly in large enterprise and campus environments during the late 1990s and 2000s.

Enterprise Wiring Closet / Access Layer Deployment

This was its most common role. A Catalyst 6509 chassis, populated with multiple WS-X6248-RJ-45 modules, could provide connectivity for hundreds of users on a floor or building.

High-Density User Access: Connect desktop PCs, analog phones (via adapters), and printers.
Integrated Uplinks: The 100BASE-FX uplinks aggregated traffic to a 1 Gbps or 10 Gbps core/distribution layer switch.
Consolidated Management: One chassis managing hundreds of ports simplified network administration.

Server Farm or Data Center Access Module

In its era, it was used to provide connectivity for racks of servers operating with 10/100 Mbps NICs.

Reliable Server Connectivity: Offered a stable, low-latency connection for business applications.
VLAN Segmentation: Isolate server tiers (web, application, database) into separate VLANs.
QoS for Critical Servers: Ensure bandwidth for priority applications.

Considerations for Modern Retrofits

While largely superseded by Gigabit and Multi-Gigabit access technologies, these modules are still found in:
Industrial control systems (ICS) with long refresh cycles.
Legacy lab or test environments.
Organizations with a "if it ain't broke, don't fix it" philosophy for non-critical segments.

Technical Considerations and Compatibility

Deploying or maintaining this module requires careful attention to system requirements and limitations.

Hardware and Software Prerequisites

The module cannot function independently. Specific chassis and supervisor engine combinations are required.

Compatibility Matrix Essentials

Minimum Supervisor Engine: Requires Supervisor Engine 1A or later for full functionality.
Minimum Cisco IOS Software: Requires Cisco IOS Software Release 7.5(1) or later. Recommended release is 12.2SX for stability and feature support.
Chassis Power: The module itself has moderate power requirements, but a chassis with adequate power supplies for the total number of modules is critical.
Fabric Compatibility: Works with both classic shared bus (Switch Fabric Module optional) and newer fabric-enabled chassis, but performance is optimized with a Switch Fabric Module (like WS-X6500-SFM).