AWS ENI, EN & EFA

Chloe McAree
2 min readFeb 22, 2021

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This is part of a blog series giving a high level overview of the different services examined on the AWS Solution Architect Associate exam, to view the whole series click here.

Elastic Network Interface (ENI) Summary

  • Essentially a virtual network card that can be attached to instances within your VPC.
  • Used to enable network connectivity for your instances.
  • Can use multiple network interfaces to create a management network.
  • Used for low budget and highly available solutions.

Enhanced Networking (EN) Summary

  • Uses single root I/O virtualisation to provide high performance networking.
  • Provides higher bandwidth and packets per second
  • No additional charges for EN, but your EC2 instances needs to support it
  • You would use EN instead of ENI when you have more network throughput.
  • Used when you need a reliably high throughput and speeds between 10–100Gbps.

Depending on instance type EN can enable:

  1. Elastic Network Adapter(ENA) → Supports network speeds of up to 100Gbps
  2. Intel 82599 Virtual Function (VF) → Supports network speeds up to 10Gbps, used for older instances.

Elastic Fabric Adapter (EFA) Summary

  • Network device you attach to EC2 instances to accelerate High Performance Computing (HPC) & ML applications.
  • Can use OS Bypass to by pass operating system and communicate directly with EFA device which enhances inter-instance communications
  • Can scale to thousands of CPUs or GPUs

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