ENA Express for Amazon EC2 instances now supports traffic between Availability Zones

Amazon Web Services has expanded its Elastic Network Adapter (ENA) Express networking feature to support high-bandwidth traffic between EC2 instances across different Availability Zones within a region. The enhancement delivers up to 25 Gbps single-flow bandwidth for cross-zone traffic, a five-fold increase over the previous 5 Gbps limit with standard ENA. ENA Express leverages AWS's Scalable Reliable Datagram (SRD) protocol, which improves network performance through advanced congestion control and multi-pathing capabilities. The feature automatically detects compatibility between EC2 instances and establishes SRD connections when both communicating instances have ENA Express enabled. Once active, the protocol uses multi-pathing to route traffic and avoids head-of-line blocking by eliminating the requirement for packets to arrive in order. This improvement particularly benefits distributed storage systems, databases, and file systems that require multi-zone deployments for resilience but previously faced bandwidth limitations for cross-zone communication. The expanded ENA Express capability is now available across 35 AWS regions at no additional cost, supporting all compatible instance types and sizes. The feature works transparently with existing TCP and UDP protocols, requiring no application modifications to realize the performance benefits.