This content originally appeared on DEV Community and was authored by Wakeup Flower
Choosing networking options on EC2.
1. Elastic Network Adapter (ENA)
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What it is:
- Default high-performance network interface for EC2.
- Provides high throughput (up to 100 Gbps) and low latency networking.
Protocol: Uses standard TCP/IP stack.
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Use cases:
- General-purpose workloads.
- Web servers, databases, enterprise apps.
- Applications that need high bandwidth but don’t require specialized HPC communication.
2. Elastic Fabric Adapter (EFA)
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What it is:
- A specialized network interface for HPC (High Performance Computing) and ML training workloads.
- Built on top of ENA, but adds OS-bypass networking with the Message Passing Interface (MPI).
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Protocol: Supports libfabric API with EFA-specific extensions.
- Allows applications to bypass parts of the kernel networking stack → reducing latency & jitter.
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Performance:
- Provides ultra-low latency, consistent performance for tightly coupled workloads.
- Can scale HPC clusters to thousands of nodes.
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Use cases:
- HPC simulations (e.g., weather modeling, CFD, molecular dynamics).
- Machine learning distributed training (e.g., TensorFlow, PyTorch with Horovod).
- Workloads using MPI that require frequent, small, low-latency communications between nodes.
Key Differences
| Feature | ENA | EFA |
|---|---|---|
| Protocol | TCP/IP stack | OS-bypass + MPI (via libfabric) |
| Latency | Low, but limited by TCP/IP | Ultra-low (microsecond-level) |
| Throughput | Up to 100 Gbps | Up to 100 Gbps (but optimized for small-message, HPC traffic) |
| Use cases | General apps, web servers, DBs, analytics | HPC, ML distributed training, tightly coupled workloads |
| Cluster scaling | Scales fine for throughput-heavy apps | Scales to thousands of nodes with consistent latency |
| Complexity | Easy — works out of the box | Requires HPC/ML apps built for MPI/libfabric |
When to Use What
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Use ENA if:
- You need general-purpose, high-bandwidth networking.
- Workloads are fine with TCP/IP latency (databases, streaming, web apps, microservices).
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Use EFA if:
- You’re running HPC or distributed ML workloads that rely on MPI-style communication.
- Your workloads require very low latency and consistent communication between nodes.
- You want to scale workloads across thousands of EC2 instances efficiently.
Quick analogy:
- ENA = highway built for moving lots of traffic fast (bulk data transfer).
- EFA = dedicated racing track for specialized cars (HPC/ML apps needing ultra-low latency).
This content originally appeared on DEV Community and was authored by Wakeup Flower