WS-X6724-SFP Cisco Gigabit Ethernet Interface Module

Cisco WS-X6724-SFP Ethernet Interface Module Overview

The Cisco WS-X6724-SFP is a powerful Gigabit Ethernet switching module designed to enhance network performance in enterprise, core, and data center environments. Built for reliability and scalability, this module delivers advanced traffic handling and seamless integration with Cisco Catalyst 6500 Series switches.

General Product Details

• Brand: Cisco Systems
• Model Number: WS-X6724-SFP
• Product Category: Network Switching Module

Expansion and Port Configuration

This Cisco interface module provides flexible expansion options, making it ideal for growing network infrastructures.

• Total Ports: 24 expansion slots
• Port Type: SFP (mini-GBIC) for fiber connectivity

Performance and Traffic Management Features

Engineered for high-throughput environments, the WS-X6724-SFP ensures optimized data flow and efficient packet processing.

Primary Applications

• Enterprise distribution layer deployments
• Core network switching
• High-demand data center operations

Interface Architecture

• Module Class: CEF720
• Scheduling Method: Weighted Round Robin (WRR)

Queue and Buffer Specifications

• Transmit Queues: 1p3q8T per port
• Receive Queues: 1q8T (up to 2q8T with CEF enabled)
• Receive Buffer Capacity: 166 KB
• Transmit Buffer Capacity: 1.17 MB

Technical Architecture and Core Features

Understanding the internal architecture of the WS-X6724-SFP is key to appreciating its capabilities within the modular chassis ecosystem.

Hardware Specifications and Data Plane

Built on a high-performance ASIC design, the module provides 24 dedicated Gigabit Ethernet ports, each supporting a wide range of Cisco SFP (Small Form-Factor Pluggable) transceivers. The module connects to the chassis backplane via a high-bandwidth channel, ensuring non-blocking performance for all ports simultaneously. Its shared memory architecture and sophisticated queuing mechanisms prevent head-of-line blocking and ensure predictable latency, even under extreme load.

Backplane Connectivity and Bandwidth Allocation

The WS-X6724-SFP typically utilizes a 20 Gbps full-duplex connection to the Catalyst 6500 Series Switch Fabric (when installed in a fabric-enabled chassis). This design guarantees that all 24 ports can operate at wire speed simultaneously without contention, a crucial requirement for aggregation and server connectivity roles. The module intelligently manages buffer allocation to optimize throughput for mixed traffic profiles.

Port-by-Port Autonegotiation and Capabilities

Each of the 24 ports independently negotiates speed (10/100/1000 Mbps) and duplex settings when using copper SFPs (like GLC-T), while fiber SFPs operate at fixed rates. Advanced features like IEEE 802.3x flow control, jumbo frame support (up to 9216 bytes), and Layer 2 protocol tuning are configurable per port, providing granular control for diverse connected devices.

Supervisor Engine Compatibility and System Synergy

The module's functionality is deeply integrated with the chassis Supervisor Engine. It is compatible with a wide range of supervisors, from the Supervisor Engine 720 to the Supervisor Engine 2T, with features and performance scaling accordingly. Key integrated services include:

Advanced QoS: Leverages the chassis policing and marking capabilities for complex service policies.
Unified Management: Configured entirely through the Supervisor's Cisco IOS® or Cisco IOS® XE Software CLI.
High Availability: Works in tandem with supervisor redundancy and Stateful Switchover (SSO) for hitless failover.

Deployment Scenarios and Use Cases

The versatility of the WS-X6724-SFP makes it suitable for several critical network roles, often defining the aggregation layer of modern enterprise networks.

Data Center Server Farm Aggregation

In server consolidation projects, multiple WS-X6724-SFP modules can be deployed within a Catalyst 6500-E chassis to provide hundreds of Gigabit Ethernet server connections. Proximity to core routers and integrated services like Firewall and Load Balancer modules (via the chassis backplane) make it an ideal top-of-rack or end-of-row aggregation switch. Features like NIC teaming (EtherChannel) support and rapid spanning-tree convergence are essential here.

Virtualization Host Connectivity

For VMware ESXi or Microsoft Hyper-V hosts, the module provides the high-density, low-latency ports required for vSphere distributed switches, VM traffic, vMotion, and storage networking (iSCSI or NFS). Configuring dedicated VLANs and QoS policies per port group is streamlined through the module's flexible interface configuration.

Enterprise Campus Building Distribution

Acting as a building distribution switch, the module aggregates traffic from multiple wiring closet access switches (e.g., Catalyst 3750 stacks) over Gigabit Ethernet fiber uplinks. It performs inter-VLAN routing, applies security policies, and aggregates traffic toward the campus core. Its support for routing protocols (via the supervisor) and high resilience makes it perfect for this role.

High-Performance Workgroup Cluster

In engineering, financial, or scientific environments, workgroups often require high-speed access to localized servers and storage. A dedicated WS-X6724-SFP module can segment this cluster, providing wire-speed Layer 2 switching and low-latency Layer 3 routing within the workgroup, while controlling upstream traffic via policy.

Advanced Software Features and Configuration

Running Cisco IOS® Software, the module supports the full suite of Catalyst 6500 features, turning a simple interface module into an intelligent switching powerhouse.

Layer 2 Switching Capabilities

The module delivers comprehensive Layer 2 features essential for any modern switched network.

VLAN and Spanning Tree Protocol Suite

It supports 4094 VLANs (per IEEE 802.1Q), with VLAN Trunking Protocol (VTP) modes for efficient management. For loop prevention and convergence, it offers Per-VLAN Spanning Tree Plus (PVST+), Rapid PVST+ (IEEE 802.1w), and Multiple Spanning Tree (MST) Protocol, allowing for optimized path selection and sub-second recovery.

EtherChannel and Link Aggregation

Up to eight physical ports can be bundled into a single logical EtherChannel group (using PAgP or LACP), providing fault tolerance, load balancing, and scalable bandwidth up to 8 Gbps (full-duplex) for critical uplinks or server connections.

Layer 3 IP Routing Performance

When paired with a Supervisor Engine supporting Layer 3 switching, the WS-X6724-SFP ports become fully routable interfaces.

Routing Protocol Support

The module participates in the chassis's distributed routing architecture, supporting static routing, RIP, OSPF, EIGRP, and BGP. Routing is hardware-accelerated, ensuring wire-speed performance regardless of protocol or table size.

Access Control Lists and Security

It supports the application of standard and extended IP ACLs (and MAC ACLs) on any interface to control traffic flow. These ACLs are compiled into Ternary Content-Addressable Memory (TCAM) entries on the module itself, enforcing security policies at line rate without performance degradation.

SFP Transceiver Compatibility and Optical Considerations

The "SFP" in the module's name highlights its flexibility; the physical media is determined by the plugged-in transceiver.

Supported SFP Types and Distance Limitations

The WS-X6724-SFP accepts a vast array of Cisco-branded and compatible SFP modules, including:

GLC-T & GLC-TE: 1000BASE-T Copper RJ-45 SFP for Cat5e/6 up to 100m.
GLC-SX-MM: 1000BASE-SX Multimode Fiber for distances up to 550m.
GLC-LH-SM: 1000BASE-LX/LH Single-mode Fiber for distances up to 10km.
GLC-ZX-SM: 1000BASE-ZX Extended Reach Single-mode for distances up to 70km.
CWDM SFPs: For bandwidth consolidation over colored optics.

This allows a single module to connect to a mix of copper server NICs, short-haul multimode fiber, and long-distance single-mode fiber uplinks.

Integration in Virtual Switching System (VSS)

In advanced deployments, the Catalyst 6500 chassis housing WS-X6724-SFP modules can be configured in a Virtual Switching System (VSS).

VSS Benefits for Module Ports

VSS combines two physical chassis into a single logical management entity. From the perspective of the WS-X6724-SFP ports, this enables:

Multi-Chassis EtherChannel (MEC): Ports on modules in two separate chassis can be bundled into a single EtherChannel, providing unparalleled uplink redundancy and active/active load balancing.
Hitless Failover: In a VSS pair, if one supervisor fails, the other instantly assumes control of all modules in both chassis, with sub-second data plane convergence.
Simplified Management: The entire VSS pair is managed as one switch, halving the management overhead for configurations spanning the aggregation layer.

Redundancy and High-Availability Features

Network uptime is paramount, and the WS-X6724-SFP operates within a chassis designed for maximum resilience.

Module-Level Redundancy

While the module itself is not hot-swappable in all chassis modes without potential service impact (depending on configuration), multiple WS-X6724-SFP modules can be deployed for port density and redundancy. Link-level redundancy is achieved via EtherChannel or spanning tree across modules.

Chassis-Level Support Systems

The module fully benefits from the Catalyst 6500's robust platform:

Dual Supervisors with SSO/NSF: Stateful Switchover (SSO) and Non-Stop Forwarding (NSF) ensure control plane and data plane continuity during supervisor switchover.
Redundant Power Supplies: The module draws power from the chassis's redundant power bus.
Online Insertion and Removal (OIR): Modules can be added or replaced while the system is operational, minimizing downtime for upgrades.