A route-based VPN creates an IPsec tunnel interface and routes traffic through it as dictated by the SDDC routing table. A route-based VPN provides resilient, secure access to multiple subnets. When you use a route-based VPN, new routes are added automatically when new networks are created.

Route based VPNs in your VMware Cloud on AWS GovCloud SDDC use an IPsec protocol to secure traffic and the Border Gateway Protocol (BGP) to discover and propagate routes as networks are added and removed. To create a route-based VPN, you configure BGP information for the local (SDDC) and remote (on-premises) endpoints, then specify tunnel security parameters for the SDDC end of the tunnel.
Important:

If your SDDC includes both a policy-based VPN and a route-based VPN, connectivity over the policy-based VPN will fail if the route-based VPN advertises the default route (0.0.0.0/0) to the SDDC.

Procedure

  1. Log in to the VMware Cloud on AWS GovCloud at https://www.vmc-us-gov.vmware.com/.
  2. Click Networking & Security > VPN > Route Based.
  3. (Optional) Change the default local Autonomous System Number (ASN).
    All route-based VPNs in the SDDC default to ASN 65000. The local ASN must be different from the remote ASN. (iBGP, which requires the local and remote ASNs to be the same, is not supported in SDDC networks.) To change the default local ASN, click EDIT LOCAL ASN, enter a new value in the range 64521 to 65535 (or 4200000000 to 4294967294) and click AActivate or deactivatePPLY.
    Note: Any change in this value affects all route-based VPNs in this SDDC.
  4. Click ADD VPN and give the new VPN a Name and optional Description.
  5. Select a Local IP Address from the drop-down menu.
    • If this SDDC is member of an SDDC group or has been configured to use AWS Direct Connect, select the private IP address to have the VPN use that connection rather than a connection over the Internet. Note that VPN traffic over Direct Connect or VMware Managed Transit Gateway (VTGW) is limited to the default MTU of 1500 bytes even if the link supports a higher MTU. See Configure Direct Connect to a Private Virtual Interface for SDDC Management and Compute Network Traffic.
    • Select the public IP address if you want the VPN to connect over the Internet.
  6. For Remote Public IP, enter the address of your on-premises VPN endpoint.
    This is the address of the device that initiates or responds to IPsec requests for this VPN. This address must meet the following requirements:
    • It must not already be in use for another VPN. VMware Cloud on AWS GovCloud uses the same public IP for all VPN connections, so only a single VPN connection (Route-based, Policy-based, or L2VPN) can be created to a given remote public IP.
    • It must be reachable over the Internet if you specified a public IP in Step 5.
    • It must be reachable over VTGW or Direct Connect to a private VIF if you specified a private IP in Step 5.
    Default gateway firewall rules allow inbound and outbound traffic over the VPN connection, but you must create firewall rules to manage traffic over the VPN tunnel.
  7. For BGP Local IP/Prefix Length, enter a network address from a CIDR block of size of /30 within the 169.254.0.0/16 subnet.

    Some blocks in this range are reserved, as noted in NSX-T Networking Concepts. If you can't use a network from the 169.254.0.0/16 subnet (due to a conflict with an existing network), you must create a firewall rule that allows traffic from the BGP service to the subnet you choose here. See Add or Modify Compute Gateway Firewall Rules.

    The BGP Local IP/Prefix Length specifies both a local subnet and an IP address in it, so the value you enter must be the second or third address in a /30 range and include the /30 suffix. For example, a BGP Local IP/Prefix Length of 169.254.32.1/30 creates network 169.254.32.0 and assigns 169.254.32.1 as the local BGP IP (also known as the Virtual Tunnel Interface, or VTI).

  8. For BGP Remote IP, enter the remaining IP address from the range you specified in Step 7.
    For example, if you specified a BGP Local IP/Prefix Length of 169.254.32.1/30, use 169.254.32.2 for BGP Remote IP. When configuring the on-premises end of this VPN, use the IP address you specify for BGP Remote IP as its local BGP IP or VTI address.
  9. For BGP Neighbor ASN, enter the ASN of your on-premises VPN gateway.
  10. Configure Advanced Tunnel Parameters.
    Option Description
    Tunnel Encryption Select a Phase 2 security association (SA) cipher that is supported by your on-premises VPN gateway.
    Tunnel Digest Algorithm Select a Phase 2 digest algorithm that is supported by your on-premises VPN gateway.
    Note:

    If you specify a GCM-based cipher for Tunnel Encryption, set Tunnel Digest Algorithm to None. The digest function is integral to the GCM cipher.

    Perfect Forward Secrecy Activate or deactivate to match the setting of your on-premises VPN gateway. Enabling Perfect Forward Secrecy prevents recorded (past) sessions from being decrypted if the private key is ever compromised.
    Preshared Key Enter the preshared key string.

    The maximum key length is 128 characters. This key must be identical for both ends of the VPN tunnel.

    Remote Private IP Leave this blank to use the Remote Public IP as the remote ID for IKE negotiation. If your on-premises VPN gateway is behind a NAT device and/or uses a different IP for its local ID, you need to enter that IP here.
    IKE Encryption Select a Phase 1 (IKE) cipher that is supported by your on-premises VPN gateway.
    IKE Digest Algorithm Select a Phase 1 digest algorithm that is supported by your on-premises VPN gateway. The best practice is to use the same algorithm for both the IKE Digest Algorithm and the Tunnel Digest Algorithm.
    Note:

    If you specify a GCM-based cipher for IKE Encryption, set IKE Digest Algorithm to None. The digest function is integral to the GCM cipher. You must use IKE V2 if you use a GCM-based cipher

    .
    IKE Type
    • Specify IKE V1 to initiate and accept the IKEv1 protocol.
    • Specify IKE V2 to initiate and accept the IKEv2 protocol. You must use IKEv2 if you have specified a GCM-based IKE Digest Algorithm.
    • Specify IKE FLEX to accept either IKEv1 or IKEv2 and then initiate using IKEv2. If IKEv2 initiation fails, IKE FLEX will not fall back to IKEv1.
    Diffie Hellman Select a Diffie Hellman group that is supported by your on-premises VPN gateway. This value must be identical for both ends of the VPN tunnel. Higher group numbers offer better protection. The best practice is to select group 14 or higher.
    Connection Initiation Mode Connection initiation mode defines the policy used by the local endpoint in the process of tunnel creation. The following modes are available.
    Initiator
    The default value. In this mode, the local endpoint initiates VPN tunnel creation and responds to incoming tunnel setup requests from the peer gateway.
    On Demand
    N/A for route-based VPN.
    Respond Only
    In this mode, the VPN never initiates a connection. The peer site always initiates the connection request and the local endpoint responds to that connection request.
    TCP MSS Clamping To reduce the maximum segment size (MSS) payload of the TCP session during the IPsec connection, enable TCP MSS Clamping, select the TCP MSS direction value, and optionally set the TCP MSS Value. See Understanding TCP MSS Clamping in the NSX-T Data Center Administration Guide.
  11. (Optional) Under Advanced BGP Parameters, enter a BGP Secret that matches the one used by the on-premises gateway.
  12. (Optional) Tag the VPN.

    See Add Tags to an Object in the NSX-T Data Center Administration Guide for more information about tagging NSX-T objects.

  13. Click SAVE.

Results

The VPN creation process might take a few minutes. When the route-based VPN becomes available, the tunnel status and BGP session state are displayed. The following actions are available to help you with troubleshooting and configuring the on-premises end of the VPN:
  • Click DOWNLOAD CONFIG to download a file that contains VPN configuration details. You can use these details to configure the on-premises end of this VPN.
  • Click VIEW STATISTICS to view packet traffic statistics for this VPN. See View VPN Tunnel Status and Statistics.
  • Click VIEW ROUTES to open a display of routes advertised and learned by this VPN.
  • Click DOWNLOAD ROUTES to download a list of Advertised Routes or Learned Routes in CSV format.

What to do next

Create or update firewall rules as needed. To allow traffic through the route-based VPN, specify VPN Tunnel Interface in the Applied to field. The All Uplinks option does not include the routed VPN tunnel.