Use of AWS Direct Connect is optional. If traffic between your on-premises network and your SDDC workloads requires higher speeds and lower latency than you can achieve with a connection over the public Internet, configure VMware Cloud on AWS to use AWS Direct Connect.

There are a couple of ways you can configure your VMware Cloud on AWS SDDC to take advantage of AWS Direct Connect for traffic to and from your on-premises datacenter:
Configure Direct Connect to a private VIF in your VPC.
AWS Direct Connect (DX) provides a dedicated network connection between your on-premises network infrastructure and a virtual interface (VIF) in your AWS VPC. A private VIF provides direct private access to your SDDC. Configure DX over a private VIF to carry workload and management traffic, including VPN and vMotion, between your on-premises data center and your connected VPC. A DX connection over a private VIF can be used for all traffic between your on-premises data center and your SDDC. It terminates in your connected Amazon VPC, provides a private IP address space, and uses BGP to advertise routes in your SDDC and learn routes in your on-premise data center. Provisioning procedures for this VIF depend on the type of DX connection you choose.
Associate a Direct Connect Gateway with your SDDC Group's VMware Managed Transit Gateway.
If you have created an SDDC Group in your VMware Cloud on AWS organization, you can connect an on-premises SDDC to that group's Direct Connect Gateway to give it DX connectivity to all members of the SDDC group. See Attach a Direct Connect Gateway to an SDDC Group in the VMware Cloud on AWS Operations Guide.
Access AWS services over a public VIF
If you just want to use DX to access AWS services in a VPC you own, you can do so over a public VIF. You cannot use a public VIF to carry the same kinds of SDDC traffic (such as vMotion) that require a private VIF or Direct Connect Gateway.