DCS-7124S-F Arista DCS-7124S 10GbE SFP+ 24 Ports Layer 4 Managed Rear-to-Front Airflow Switch

Arista DCS-7124S-F 24 Ports Airflow Switch

The Arista 7100 Series represents a cornerstone of modern data center and high-performance computing (HPC) networks, delivering robust, low-latency 10 Gigabit Ethernet switching. Designed with performance and reliability at its core, this series is built to handle the most demanding workloads. Within this esteemed family, the Arista DCS-7124S-F emerges as a specialized solution, offering a unique combination of port density, advanced traffic management, and a cooling design tailored for specific data center architectures.

Focus of the DCS-7124S-F Model: Core Architecture

The Arista DCS-7124S-F is a 1U rack-mountable, Layer 4 managed Ethernet switch providing twenty-four fixed 10 Gigabit Ethernet SFP+ ports. It is engineered on Arista's Extensible Operating System (EOS®), a fully programmable and highly resilient network operating system. This switch distinguishes itself with its rear-to-front airflow design, a critical feature for deployment in data centers with alternating hot and cold aisle containment configured for this specific airflow pattern.

Core Specifications

The switch is built with a robust metal chassis designed for standard 19-inch rack mounting. Its 1U form factor optimizes rack space, allowing for high port density per rack unit. The power supplies and fan modules are field-replaceable units (FRUs), ensuring minimal downtime in the event of a component failure and facilitating easy maintenance.

Port Configuration and Connectivity

The front panel of the DCS-7124S-F is dedicated to network connectivity, housing all 24 SFP+ ports. These ports support 10GbE connectivity via SFP+ direct-attach copper cables or optical transceivers, providing flexibility for short-reach (DAC) or long-reach (optical) connections. The switch does not include embedded 1GbE or management ports on the front; out-of-band management is typically achieved via a dedicated 10/100/1000BASE-T Ethernet port located on the rear.

Cooling System and Airflow Direction

The rear-to-front (F) airflow is the defining characteristic of this model. In this configuration, ambient air is drawn in from the rear of the switch and exhausted out the front. This is the inverse of the more common front-to-rear design. This is essential for proper thermal management in data centers where the hot aisle is at the front of the rack and the cold aisle is at the rear. Deploying a switch with mismatched airflow can lead to overheating and reduced hardware lifespan.

Power Supply Options

The DCS-7124S-F is typically offered with multiple, redundant AC power supply options. These hot-swappable power supplies enhance system availability. The specific wattage and efficiency (e.g., 80 Plus Platinum) vary by configuration but are selected to support the full load of all 24 SFP+ ports populated with optical transceivers.

Layer 3 and Layer 4 Feature Set

While a Layer 2/3 switch, the DCS-7124S-F is classified as Layer 4 managed due to its advanced capabilities that operate at the transport layer. It supports static routing and dynamic routing protocols such as OSPF, BGP, and IS-IS, making it suitable for both data center spine and leaf roles in smaller deployments or as a top-of-rack (ToR) switch.

Advanced Layer 4 Switching

As a Layer 4 managed switch, the DCS-7124S-F provides intelligence that extends beyond basic Layer 2 switching and Layer 3 routing.

Comprehensive Layer 2/3 Protocols

The switch supports a full suite of standards-based protocols. Layer 2 features include IEEE 802.1Q VLANs, 802.1ad (Q-in-Q), Multiple Spanning Tree Protocol (MSTP), Rapid Spanning Tree (RSTP), and Link Aggregation Control Protocol (LACP) for bundling up to 16 ports into a single logical trunk. Layer 3 routing includes static routing, OSPFv2/v3, BGP, and VRRP for first-hop redundancy.

Layer 4-Awareness

The Layer 4 capabilities allow the switch to make forwarding and prioritization decisions based on TCP/UDP port numbers. This enables advanced Quality of Service (QoS) policies. Network administrators can classify, police, shape, and queue traffic based on application type (e.g., prioritize VoIP traffic on UDP port 5060, or storage traffic on TCP port 3260 for iSCSI). The switch supports 8 hardware queues per port and sophisticated scheduling algorithms like Deficit Weighted Round Robin (DWRR) and Strict Priority Queuing.

Access Control Lists (ACLs) and Security

The switch supports large-scale ingress and egress ACLs that can match on Layer 2, 3, and 4 fields. This provides powerful security and traffic control at wire speed. Features like DHCP snooping, Dynamic ARP Inspection (DAI), and IP Source Guard help secure the network edge against spoofing and man-in-the-middle attacks.

Performance and Scalability Characteristics

The DCS-7124S-F is designed for wire-speed performance. Its switching capacity is 480 Gbps (full-duplex), providing non-blocking throughput for all 24 ports simultaneously. The packet buffer memory is sized to handle microbursts and traffic spikes common in data center environments, ensuring low jitter and predictable latency.

Latency and Jitter Performance

Arista switches are renowned for their predictable, low latency. The DCS-7124S-F utilizes cut-through switching technology where possible, which significantly reduces forwarding latency compared to store-and-forward switches. This is crucial for financial trading, HPC, and real-time analytics applications.

Scalability and Virtualization Features

The switch supports large Layer 2 and Layer 3 forwarding tables. For network virtualization, it fully supports VLANs (802.1Q), VXLAN routing and bridging (with hardware-based VXLAN gateways), and Multi-Chassis Link Aggregation (MLAG), which allows two switches to act as a single logical device for high availability.

Primary Use Cases and Deployment Scenarios

The specific airflow design and performance profile of the DCS-7124S-F make it ideal for several targeted deployment scenarios within modern data centers.

Data Center Top-of-Rack (ToR) Deployment

This is the most common role for the 7124S-F. It serves as the network aggregation point for a rack of servers, providing high-bandwidth 10GbE connectivity to each server. Its rear-to-front airflow makes it perfect for racks where server fans also exhaust front-to-rear, creating a consistent thermal zone. It connects upstream to spine switches or data center core switches via its SFP+ ports, often using 40GbE or 100GbE uplink modules if supported by the specific variant or via breakout cables.

High-Performance Computing Clusters

In HPC environments, low and predictable latency is paramount. The DCS-7124S-F's performance characteristics, combined with support for lossless Ethernet (Data Center Bridging - DCB) and integration with RDMA over Converged Ethernet (RoCE) workloads, make it a strong candidate for building high-speed compute and storage interconnects.

Consistent Airflow Containment Environments

Data centers employing hot aisle/cold aisle containment rigorously enforce equipment airflow direction to maximize cooling efficiency. The DCS-7124S-F is purpose-built for racks designated as "reverse airflow" or where the cold aisle is located at the rear of the rack. Using this switch ensures compliance with the thermal design, preventing hot air recirculation and cooling inefficiencies.

Comparison and Context Within the 7100 Series

Understanding the DCS-7124S-F requires seeing its place in the broader 7100 Series portfolio. The series includes variants with different port densities (e.g., 48-port models), mixed speed ports (1GbE/10GbE), and different airflow directions (front-to-rear and rear-to-front). The "S" in the model name typically denotes a "scalable" or "specialized" SKU, often with deep buffers or specific feature optimizations compared to the base 7124 model. The "F" suffix explicitly denotes the rear-to-front airflow, whereas a similar model with front-to-rear airflow might carry an "R" suffix or no suffix.

Key Differentiators of the DCS-7124S-F

The primary differentiator is the rear-to-front airflow, making it a niche but critical product for specific thermal designs. It offers a balanced 24-port configuration, which is often the sweet spot for server rack density. Its advanced Layer 4 capabilities and programmability via EOS set it apart from more basic managed switches, positioning it as an intelligent, software-driven platform rather than just a hardware appliance.