How can I validate Ethernet fabric behavior before deploying a full data center rack?

Building an entire rack of switches, servers, and NICs just to validate fabric behavior is costly, time-consuming, and limits flexibility. A fabric emulator provides a software-defined way to virtualize complete Ethernet topologies, including two- and three-tier Clos architectures, with programmable oversubscription ratios, L2/L3 switching, and realistic port speeds from 25GE to 200GE. This allows you to model the full behavior of a data center fabric before hardware is available or fully integrated. By emulating realistic traffic flows, congestion, and failover conditions, you can validate switch silicon, NIC drivers, or DPU firmware in a controllable, repeatable lab environment. This reduces risk during design, accelerates bring-up, and ensures your architecture will scale effectively once deployed in production.

What makes fabric emulation different from traditional traffic generation or simulation tools?

Conventional traffic generators primarily validate link or application-level performance. Fabric emulation goes further by modeling the network as a complete system, reproducing end-to-end switching, path diversity, ECMP routing behavior, and congestion dynamics across hundreds or thousands of logical ports. Instead of requiring racks of servers, a fabric emulator acts as a virtual, rack-scale testbed where you can tune QoS policies, FEC negotiation, flow hashing, and buffer management. This system-level visibility is especially critical for AI/ML clusters, where efficiency depends on how data moves across the entire fabric, not just on raw throughput. Emulation gives engineers, hyperscalers, and integrators the ability to evaluate large-scale topologies with precision before real infrastructure is deployed.

How can I test congestion, packet drops, and edge-case scenarios without real workloads?

One of the most powerful advantages of a fabric emulator is its ability to introduce controlled impairments and stress conditions. You can generate congestion hotspots, inject bursty microtraffic, simulate background loads, or drop packets deliberately to test recovery mechanisms. These capabilities let you observe how your fabric responds to ECN marking, queue buildup, head-of-line blocking, or flow control events. Rather than relying on hundreds of test servers to create unpredictable workloads, a fabric emulator gives you direct control over when and where stress occurs. Combined with built-in telemetry and analytics, this enables deeper debugging, faster iteration, and more confident optimization of data plane behavior. For chipmakers, system vendors, and cloud providers, it means validating large-scale network resilience and fairness long before deploying the first rack.

Fabric Emulator

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Test complex topologies to accelerate data center validation

Keysight Fabric Emulator is a software-defined platform that emulates complex, multi-switch Ethernet-based data center topologies. It enables engineers to validate adjacent switches, network interface cards (NICs), data processing units (DPUs), and high-performance interconnects for network infrastructure during design, validation, and pre-deployment stages. It emulates realistic traffic patterns, congestion, and failure conditions to help chipmakers, hyperscale cloud providers, and system integrators reduce risk, accelerate development, and validate large-scale network performance in the lab. Select a model based on the number of concurrent hardware switches you need to achieve your desired scale, typically one or two. Request a quote for one of our popular configurations today. Need help selecting? Check out the resources below.

Realistic topology emulation

Emulate entire two- or three-tier Clos network topologies with programmable oversubscription, Layer 2 switching, Layer 3 routing, and configurable port speeds.

Configurable data plane

Test realistic load balancing and routing using five-tuple or three-tuple hashing, with configurable quality-of-service and explicit congestion notification.

Impairment testing

Simulate congestion, packet drops, and background load up to 1 Tbps to observe system behavior under failure and stress conditions.

Scenario experimentation

Analyze network response to congestion and failures using controlled background traffic, packet loss simulation, and multi-tier chaos experiments.

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Fabric Emulator Emulate data center networks on a single hardware appliance