C1-N5624-B-24Q Cisco ONE Nexus 5624Q Chassis

The Foundation of High-Density, Low-Latency Data Centers

The Cisco C1-N5624-B-24Q ONE Nexus 5624Q Chassis represents a pivotal evolution in data center switching, engineered for environments where uncompromising performance, ultra-low latency, and flexible connectivity are non-negotiable. As a standalone 1-Rack-Unit (1RU) switch, the Nexus 5624Q is not merely a piece of hardware; it is the core architectural element for unifying storage and data networks, enabling high-performance computing (HPC), and providing critical fabric extender (FEX) aggregation. Its defining characteristic is the innovative design featuring four fixed 40 Gigabit Ethernet QSFP+ ports and 24 fixed 10 Gigabit Ethernet SFP+ ports, a configuration that offers unparalleled deployment flexibility for a wide array of data center topologies.

This switch belongs to the esteemed Cisco Nexus 5600 platform family, renowned for its lossless Ethernet capabilities and deep buffer memory, which are essential for handling bursty traffic patterns common in financial trading, virtualized server farms, and converged storage environments. By deploying the Nexus 5624Q, organizations build a network foundation that is both robust for today's demands and agile enough to adapt to tomorrow's technologies, such as 40GbE uplinks and beyond.

Architectural Overview and Key Specifications

At its core, the Cisco Nexus 5624Q is built to deliver wire-speed performance across all ports simultaneously, ensuring no bottlenecks in high-throughput applications. Its architecture is optimized for deterministic latency and high availability, making it a trusted component in mission-critical infrastructure.

Hardware Design and Form Factor

The compact 1RU chassis is designed for maximum port density and power efficiency. The front panel's clear division of 10G and 40G ports allows for intuitive cabling and planning.

Port Configuration and Flexibility

The fixed port arrangement is strategically designed:

24 x SFP+ Ports: These 10 Gigabit Ethernet ports support a vast ecosystem of Cisco and third-party optics, including Twinax copper cables for short-reach connections and optical modules for longer distances. They are ideally suited for server access, connecting to blade chassis, or aggregating traffic from top-of-rack switches.
4 x QSFP+ Ports: These 40 Gigabit Ethernet ports are the workhorses for high-bandwidth aggregation. Each QSFP+ port can operate natively at 40G, or it can be broken out (using a cable like QSFP-4xSFP10G-CU1M) into four independent 10 Gigabit Ethernet connections. This breakout capability effectively transforms the switch into a 40-port 10G switch (24 fixed + 16 from breakouts), offering incredible design flexibility.

Performance and Buffering Engine

Beyond raw port count, the internal architecture defines its capability. The switch features a deep packet buffer of 2 GB shared across all ports. This substantial buffering is critical for preventing packet loss during periods of congestion, especially in converged networks carrying storage traffic (like FCoE or iSCSI) where a single dropped frame can cause significant performance degradation.

Latency Characteristics

The Nexus 5624Q provides consistently low latency, typically in the sub-microsecond range for cut-through switching mode. This deterministic performance is a key requirement for latency-sensitive applications like high-frequency trading (HFT) and real-time data analytics.

Switching Capacity and Throughput

With a total switching capacity of 1.28 Tbps and a forwarding rate of 960 million packets per second (Mpps), the chassis ensures full non-blocking performance, guaranteeing that traffic can flow seamlessly between any port at line rate without contention.

Primary Deployment Use Cases and Applications

The versatility of the Nexus 5624Q's port configuration allows it to excel in several distinct roles within the data center. Its value is realized in how it simplifies architecture while boosting performance.

Unified Fabric and Data Center Convergence

The Nexus 5624Q is a cornerstone of Cisco's Unified Fabric strategy, which aims to consolidate LAN, SAN, and HPC clusters onto a single Ethernet fabric.

Fibre Channel over Ethernet (FCoE) and Storage Integration

By supporting Data Center Bridging (DCB) protocols—Priority Flow Control (PFC), Enhanced Transmission Selection (ETS), and Data Center Bridging Exchange (DCBX)—the switch creates a lossless Ethernet fabric. This allows the reliable transport of Fibre Channel storage traffic (FCoE) alongside traditional IP data. Organizations can use the 5624Q as a Converged Network Adapter (CNA) aggregator, reducing the number of adapters per server, cabling, and switches while maintaining SAN integrity.

High-Performance Computing (HPC) and Financial Networks

In environments where microseconds matter, the switch's low-latency and high-throughput characteristics are paramount.

Clustering and Grid Computing Interconnect

The high-bandwidth 40G ports are perfect for building low-latency leaf-and-spine or mesh topologies for HPC clusters. The ability to use the QSFP+ ports for 40G spine links or break them out for high-density 10G server connections provides excellent topology flexibility for compute and render farms.

Cisco Fabric Extender (FEX) Aggregation

A quintessential role for the Nexus 5624Q is acting as a parent switch for Cisco Nexus 2000 Series Fabric Extenders (such as the 2248TP or 2232PP).

Scalable Server Access Topology

By connecting FEXs via the 10G SFP+ ports, the 5624Q can manage hundreds of server ports as if they were locally attached, creating a single management domain and a highly scalable, cost-effective server access layer. The deep buffers in the 5624Q effectively absorb traffic bursts from the dozens of servers connected downstream through the FEXs.

Data Center Interconnect (DCI) and Core Aggregation

The native 40G QSFP+ ports make the switch an excellent candidate for cost-effective data center interconnect links or for serving as a compact core/aggregation switch in medium-sized deployments, providing high-speed connectivity between server blocks and to the WAN/router edge.

Software Features and Capabilities (NX-OS)

The hardware is empowered by Cisco's robust, carrier-class NX-OS operating system. This mature, Linux-based OS provides stability, feature richness, and automation capabilities that are critical for modern data centers.

Virtualization and Segmentation

NX-OS offers comprehensive network virtualization features that maximize resource utilization and enhance security.

Virtual Device Contexts (VDCs)

A powerful feature that allows a single physical Nexus 5624Q chassis to be partitioned into multiple logical switches (up to 4 VDCs). Each VDC operates independently with its own management, control plane, and data plane. This enables operational separation (e.g., dev/test vs. production) or functional separation (storage vs. data traffic) on a single device.

VRF-Lite and VLANs

Support for thousands of VLANs and Virtual Routing and Forwarding instances (VRF-lite) enables multi-tenant segmentation and efficient IP routing within a shared infrastructure.

High Availability and Resiliency

The platform is designed for continuous operation, a necessity for 24/7 data centers.

In-Service Software Upgrades (ISSU)

Allows for system software upgrades with no disruption to data traffic, dramatically reducing maintenance windows and improving network availability.

Graceful Insertion and Removal (GIR)

Enables an administrator to take a switch out of service for maintenance in a controlled manner, redirecting traffic before the switch is powered down.

Management and Automation

NX-OS provides multiple pathways for efficient management.

CLI, DCNM, and API Integration

The switch features a familiar Cisco CLI for precise control. For orchestration at scale, it integrates seamlessly with Cisco Data Center Network Manager (DCNM). Furthermore, it supports modern automation tools via XML API and Python scripting, laying the groundwork for Software-Defined Networking (SDN) integration and DevOps-style workflows.