In order to achieve your desired configuration, Company 1 can connect to Company 2 via an S2S VPN. This setup would enable Company 1 to communicate with Company 3's SAP HANA application via Company 2's infrastructure. Essentially, by utilizing Azure Virtual WAN's capabilities, Company 1 can connect to Company 2 via an S2S VPN and then make use of the already-existing connectivity between Company 2 and Company 3 to access the SAP HANA application. This method is predicated on the assumption that all necessary routing and permissions are set up correctly across the involved networks.
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Small Guide
Company 1 needs to set up a Site-to-Site VPN connection with Company 2. This involves configuring a VPN device at Company 1's end and connecting it to Company 2's Azure Virtual WAN hub.
Ensure that the Azure Virtual WAN hub in Company 2 is configured to allow transit connectivity. This means that the hub should facilitate communication not just to and from Company 2, but also between Company 1 and Company 3.
Set up appropriate routing rules and permissions within Company 2’s Azure Virtual WAN hub to ensure that traffic from Company 1 can reach Company 3's SAP HANA application. This includes configuring network routes and access control lists.