VIF VS ENI

ENI is like a network card for an EC2 instances, while VIF is more like a virtual cable connecting on-premises network to AWS.

The key differences between ENI (Elastic Network Interface) and VIF (Virtual Interface) are:

ENI (Elastic Network Interface):

• It's a virtual network card for EC2 instances within AWS

• Lives inside a VPC

• Operates at the instance level

• Primary uses:

  • Attaching multiple network interfaces to an EC2 instance

  • Creating management networks

  • Using network/security appliances

  • Moving network interfaces between instances

  • Having multiple IP addresses per instance

• Each ENI belongs to a specific subnet in a VPC

• Can have security groups attached

• Attributes include: private IP addresses, MAC address, source/destination check flag

VIF (Virtual Interface):

• It's a configuration object for AWS Direct Connect

• Lives at the Direct Connect level

• Operates at the connection level between AWS and on-premises

• Primary uses:

  • Creating private connections to VPCs (Private VIF)

  • Accessing AWS public services (Public VIF)

  • Connecting to Transit Gateway (Transit VIF)

• Requires BGP for routing

• Has attributes like VLAN tags and BGP ASN

• Can connect to Direct Connect Gateway or VPC

Simplified comparison:

ENI:
On-premises → Direct Connect → VPC → ENI → EC2 Instance
(Network interface inside AWS)

VIF:
On-premises → VIF → Direct Connect → AWS
(Connection interface between on-premises and AWS)