N3K-C3432D-S Cisco Nexus 3432D-S Manageable 400 Gigabit Ethernet 32 Ports Layer 3 Switch

Cisco N3K-C3432D-S 32 Ports Layer 3 Switch

The Cisco Nexus 3432D-S (N3K-C3432D-S) represents a pivotal evolution in data center access and spine-layer switching. Designed for modern, high-performance workloads, this fixed-port switch delivers unprecedented port density and speed in a compact 1-Rack-Unit (1RU) form factor. As a core component of the Cisco Nexus 3000 Series, the 3432D-S is engineered to provide cost-effective, low-latency, and high-bandwidth connectivity, making it an ideal foundation for cloud-scale deployments, high-frequency trading environments, and data centers transitioning to 400 Gigabit Ethernet architectures.

Architectural Overview and Form Factor

Housed in a sleek 1RU chassis, the Cisco N3K-C3432D-S maximizes rack space efficiency while delivering massive throughput. Its design is centered on a non-blocking, wire-rate switching fabric that ensures consistent performance across all ports simultaneously. The switch is built with a fixed configuration, simplifying deployment and reducing the operational complexity associated with modular systems. The front panel layout is meticulously organized, grouping ports logically to facilitate cabling and management in dense data center environments.

Physical Port Configuration and Layout

The defining characteristic of the Nexus 3432D-S is its innovative port arrangement, which provides flexible connectivity options for diverse network roles.

High-Density 100/400 Gigabit Ethernet Ports

The switch features 32 fixed QSFP-DD (Quad Small Form-Factor Pluggable Double Density) ports. These ports are the workhorses of the system, offering exceptional flexibility. Each QSFP-DD port can operate as a native 400 Gigabit Ethernet interface using a single QSFP-DD transceiver. Alternatively, through breakout cabling, each port can be split into either 4x 100 Gigabit Ethernet links (using QSFP-DD to 4x SFP-DD breakout cables) or 2x 200 Gigabit Ethernet links. This breakout capability effectively allows the 3432D-S to support configurations of up to 128 x 100G ports, making it one of the densest 100G platforms available in a 1RU form factor.

Dedicated Management and Uplink Slots

In addition to the 32 QSFP-DD ports, the switch includes two dedicated 1/10 Gigabit Ethernet SFP+ slots. These slots are typically utilized for switch management, out-of-band connectivity, or as traditional uplinks to higher-tier switches or routers. Their separation from the high-speed data ports ensures reliable management access even under heavy load. The switch also includes a serial console port and a USB management port for initial setup and diagnostics.

Performance and Switching Capacity

The Cisco N3K-C3432D-S Nexus 3432D-S is engineered for performance-critical applications where latency and throughput are paramount. It is built on Cisco's cutting-edge switching ASIC technology, delivering deterministic low latency and consistent performance regardless of traffic pattern or feature enablement.

Non-Blocking Fabric and Throughput

With an aggregate switching capacity of 12.8 Terabits per second (Tbps), the 3432D-S ensures full line-rate, non-blocking performance across all 32 ports simultaneously, even when operating at 400G. This massive capacity future-proofs the network, accommodating data growth and bandwidth-intensive applications like AI/ML clustering, big data analytics, and high-performance storage.

Forwarding Rate and Latency

The switch boasts a packet forwarding rate of up to 9.5 billion packets per second (Bpps), enabling it to handle massive amounts of network flows with ease. Engineered for ultra-low latency, the switch provides consistent sub-microsecond port-to-port latency, a critical feature for financial trading, high-performance computing (HPC), and distributed database applications where every nanosecond counts.

Layer 3 Features and Protocol Support

As a fully functional Layer 3 switch, the Nexus 3432D-S provides comprehensive routing capabilities, making it suitable for both leaf and spine roles in a Clos fabric architecture.

Advanced Routing Capabilities

The switch supports a full suite of IPv4 and IPv6 unicast routing protocols, including static routing, OSPF (Open Shortest Path First), OSPFv3, ISIS (Intermediate System to Intermediate System), and BGP (Border Gateway Protocol) with full Internet-scale routing tables. This enables seamless integration into existing enterprise or service provider network cores.

Multicast and Overlay Networking

For modern data centers, the switch offers rich multicast support with Protocol Independent Multicast (PIM) Sparse Mode, Source-Specific Multicast (SSM), and Bidirectional PIM. It also natively supports VXLAN (Virtual Extensible LAN) bridging and routing with EVPN (Ethernet VPN) control plane, facilitating the creation of scalable, multi-tenant network overlays that decouple the physical infrastructure from the logical network design.

Access Control and Security

Security is embedded into the switch's architecture. It offers comprehensive Access Control List (ACL) capabilities for both IPv4 and IPv6, with granular policy enforcement applied at line rate. Security features also include Control Plane Policing (CoPP) to protect the switch's CPU from malicious traffic, DHCP snooping, Dynamic ARP Inspection (DAI), and IP Source Guard to mitigate spoofing attacks.

High Availability and Reliability

Engineered for mission-critical operations, the Nexus 3432D-S incorporates multiple levels of redundancy and fault tolerance.

Hardware Resilience

The switch features redundant, hot-swappable power supplies and fan trays with front-to-back or back-to-front airflow options to match various data center cooling designs. N+1 power and cooling redundancy ensures continuous operation in the event of a component failure.

Protocol High Availability

NX-OS offers hitless failover with Stateful Switchover (SSO) and non-stop forwarding when deployed in a virtual PortChannel (vPC) configuration. The vPC technology allows dual-homing of servers or downstream switches to two upstream Nexus switches, eliminating the Spanning Tree Protocol blocking state and utilizing all available uplink bandwidth.

Traditional and Modern Management Interfaces

Management options include CLI, SNMP (v1, v2c, v3), SSHv2, and a web-based GUI (Cisco DCNM LAN Fabric Manager can also be used for centralized management). For modern monitoring, the switch supports streaming telemetry, which pushes operational data in real-time to collectors for analysis, providing a more efficient and scalable alternative to SNMP polling.

Detailed Visibility with SPAN and ERSPAN

The switch offers Switched Port Analyzer (SPAN) and Encapsulated Remote SPAN (ERSPAN), allowing traffic mirroring to local or remote monitoring tools. Advanced features like sFlow and NetFlow provide data on traffic flows for capacity planning and anomaly detection.

Deployment Use Cases and Applications

The versatility of the Cisco N3K-C3432D-S Nexus 3432D-S allows it to excel in several key data center roles.

High-Density Leaf Switch in Spine-Leaf Architecture

Its high port density and flexible breakout capabilities make it an ideal leaf switch, connecting hundreds of servers running at 25G, 100G, or 400G to a 400G spine layer, forming a scalable, low-latency Clos fabric.

Compact Spine Layer

With 32 native 400G ports, a pair of 3432D-S switches can effectively serve as the spine layer for a medium-sized leaf-spine fabric, providing high-bandwidth interconnectivity for dozens of leaf switches.

High-Performance Computing

The ultra-low latency and massive bisectional bandwidth are perfectly suited for HPC, where fast data exchange between GPU and compute nodes is critical for training times and model performance.

Data Center Interconnect (DCI)

The high-speed 400G ports can be used to link geographically dispersed data centers over dark fiber or DWDM networks, using protocols like VXLAN EVPN for extending Layer 2 domains across sites.