This whitepaper is for historical reference only. Some content might be outdated and some links might not be available.

# AWS DX – DXGW with VGW, Single Region
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 **This model is constructed of:** 
+  Single AWS Region. 
+  Dual AWS Direct Connect Connections to independent DX locations. 
+  AWS DXGW directly attached to the VPCs using VGW. 
+  Optional usage of AWS Transit Gateway for Inter-VPC communication. 

![\[Diagram showing AWS DX – DXGW with VGW, Single AWS Region\]](http://docs.aws.amazon.com/whitepapers/latest/hybrid-connectivity/images/dxgw-with-vgw-single-region.png)


 **Connectivity model attributes:** 
+  Provides the ability to connect to VPCs and DX connections in other Regions in the future. 
+  Offers automated failover with dynamic routing (BGP). 
+  With AWS Transit Gateway you can control the desired communication model among the VPCs. For more information, refer to [How transit gateways work](https://docs.aws.amazon.com/vpc/latest/tgw/how-transit-gateways-work.html). 

 **Scale considerations:** 

 Reference [AWS Direct Connect quotas](https://docs.aws.amazon.com/directconnect/latest/UserGuide/limits.html) for more information about other scale limits, such as such number of supported prefixes, number of VIFs per DX connection type (Dedicated, hosted). Some key considerations: 
+  The BGP session for a private VIF may advertise up to 100 routes each for IPv4 and IPv6. 
+  Up to 20 VPCs can be connected per DXGW over a single BGP session. If more than 20 VPCs are needed, additional DXGWs can be added to facilitate the connectivity at scale, or consider using Transit Gateway integration.
+  Additional AWS Direct Connects can be added as desired. 

 **Other considerations:** 
+  Does not incur AWS Transit Gateway related processing cost for data transfer between AWS and on-premises networks. 
+  Security groups of a remote VPC cannot be referenced over AWS Transit Gateway (need VPC peering). 
+  VPC peering can be used instead of AWS Transit Gateway to facilitate the communication between the VPCs, however, this adds operational complexity to build and manage large number VPC point-to-point peering at scale. 
+  If Inter-VPC communication is not required, neither AWS Transit Gateway nor VPC peering is required in this connectivity model.