A company will migrate from an on-premises datacenter to AWS in phases. The network engineer sets up a temporary Site-to-Site VPN terminating at a virtual private gateway while awaiting a 10 Gbps Direct Connect that the provider needs 3 months to provision. The engineer observes the VPN bandwidth is capped at 1.25 Gbps despite a capable customer gateway device. What should the engineer do to increase VPN throughput until Direct Connect is available?

The maximum throughput for a single AWS Site-to-Site VPN connection is 1.25 Gbps. To exceed this, multiple VPN tunnels must be used with Equal-Cost Multi-Path (ECMP) routing. While a virtual private gateway (VPG) supports multiple VPNs, it does not support ECMP across them. A Transit Gateway, however, does support ECMP across multiple VPN connections. Therefore, creating a Transit Gateway, attaching VPCs to it, and establishing multiple VPN connections to the Transit Gateway with ECMP enabled will allow for increased aggregate throughput beyond the single-tunnel limit. Contacting AWS Support for a quota increase or upgrading the customer gateway device will not bypass the per-tunnel throughput limit imposed by AWS.