Basics

There are two types of VPC Endpoints:

• Interface Endpoint (ENI)

• Gateway Endpoing (used for S3 and Dyname DB)

There are three types of Network Interface Types in AWS:

1. Elastic Network Interface (ENI):

• Basic networking interface that serves as a virtual network card

• Real-world example: A financial services company running both customer-facing applications and internal audit systems on the same EC2 instance

  • Primary ENI handles customer transactions on the production network

  • Secondary ENI connects to a separate, isolated network for audit logging and compliance monitoring

  • This separation ensures audit logs cannot be tampered with via the production network

• Another example: Multi-homed web application

  • Primary ENI for public internet traffic

  • Secondary ENI connected to internal services like databases

  • Enables security through network segregation without need for additional instances

1. Elastic Fabric Adapter (EFA):

• Specialized network interface for high-performance computing (HPC) workloads

• Real-world example: Pharmaceutical company running molecular dynamics simulations

  • Uses EFA-enabled instances in a cluster to simulate protein folding

  • Achieves near-bare-metal performance with OS-bypass capability

  • Reduces simulation time from days to hours

• Another example: Financial risk analysis

  • Investment bank running Monte Carlo simulations across a cluster

  • EFA enables low-latency communication between nodes

  • Processes millions of scenarios in real-time for risk calculations

1. Enhanced Networking:

• High-performance networking using SR-IOV (Single Root I/O Virtualization)

• Real-world example: Video streaming service

  • Uses enhanced networking with throughput between 10 Gbps and 100 Gbps

  • Handles thousands of concurrent video streams

  • Provides consistent low-latency delivery to end users

• Another example: Real-time gaming platform

  • Leverages enhanced networking for reliable, high-throughput game server instances

  • Supports thousands of concurrent players with minimal latency

  • Uses either Intel 82599 VF or Elastic Network Adapter (ENA) depending on instance type

Key Differences and When to Use Each:

• Use ENI when you need network segregation or multiple networks at minimal cost

• Choose EFA when you need HPC-level performance and OS-bypass capabilities

• Implement Enhanced Networking when you need reliable high bandwidth but don't require the specialized capabilities of EFA

Note that Enhanced Networking is automatically enabled on most modern EC2 instance types, while ENI and EFA require specific configuration and are used for specialized use cases.

Feature	ENI	Enhanced Networking	EFA
Protocol	TCP/IP, UDP/IP	TCP/IP, UDP/IP	SRD + libfabric
Kernel bypass	No	No	Yes
Use case	General networking	Optimized general networking	HPC/ML workloads
MPI support	No	No	Yes

Feature	Elastic Network Interface (ENI)	Elastic Fabric Adapter (EFA)	Enhanced Networking
Primary Purpose	Network connectivity for EC2 instances	High Performance Computing (HPC) and ML workloads	Improved network performance
Performance	Standard EC2 networking performance	Ultra-high performance, low latency	High performance, low latency
Max Bandwidth	Varies by instance type	Up to 100 Gbps	Up to 100 Gbps (with ENA)
Latency	Standard	Ultra-low	Low
OS-bypass	No	Yes	No
Multiple IP Addresses	Yes	No (uses single ENI)	No (feature of underlying ENI)
Attached to Instance	Can be attached/detached	Permanent for instance lifetime	Built into instance networking
MPI Support	No	Yes	No
RDMA Support	No	Yes	No
Use Cases	Network segmentation, multiple IPs, security groups	HPC, large-scale parallel processing, ML	General high-performance networking needs
Instance Type Support	All EC2 instance types	Select HPC-optimized instances	Most current generation instances
Implementation	Virtual network interface	Custom network interface	SR-IOV (ENA or Intel 82599 VF)
Additional Configuration	Manual attachment and IP configuration	Requires specific enablement	Often enabled by default, may need driver installation

AWS Network Adapters:

Feature	Elastic Network Adapter (ENA)	Intel 82599 VF	Elastic Fabric Adapter (EFA)
Primary Use	Enhanced Networking	Enhanced Networking	High Performance Computing (HPC)
Max Bandwidth	Up to 100 Gbps	Up to 10 Gbps	Up to 100 Gbps
Latency	Low	Low	Ultra-low
OS-bypass	No	No	Yes
Supported Instance Types	Most current generation	Older generation (C3, C4, R3, I2, M4)	Select HPC-optimized instances
MPI Support	No	No	Yes
RDMA Support	No	No	Yes
Libfabric Support	No	No	Yes
Best For	General purpose high performance networking	Legacy instances requiring enhanced networking	HPC and ML applications requiring the lowest latency
Implementation	SR-IOV	SR-IOV	Custom
Default on New Instances	Yes (for supported types)	No	No (requires specific enablement)