RRAS VPN Demand Dial Router Connection May Be Delayed

When you attempt to connect to a Routing and Remote Access Service (RRAS) server using a virtual private networking (VPN) port, the connection may be delayed or unsuccessful.

This behavior occurs because RRAS is unable to use VPN ports that are not configured to "Dial out and receive calls as a demand dial router."

When this behavior occurs, RRAS searches sequentially for the next available VPN interface that is configured to accept a demand dial router connection. If RRAS finds this interface before a client timeout occurs, the demand dial connection is successful. When a VPN interface is unavailable (either because it is currently in use by another client or because it is configured only to "Receive Calls as a RAS server"), the RRAS server must move on to the next available port.

To resolve this issue:

1. Determine the combined maximum number of VPN interfaces needed for Remote Access Service (RAS) clients and RRAS demand dial connections.
2. Configure all VPN interfaces to "Dial out and receive calls as a demand dial router" and "Receive Calls as a RAS server" (RRAS determines what type of connection is needed).

The following example illustrates this problem. The server in this example has five VPN interfaces (VPN1-VPN5), and no connections are made to the RRAS server:

• VPN1, VPN3, and VPN5 are configured to "Receive Calls as a RAS server" and "Dial out and receive calls as a demand dial router."
• VPN2 and VPN4 are configured to "Receive Calls as a RAS server."

If all interfaces are available, the first demand dial router connection attempt from another RRAS server to the example server is successful and a connection is made to VPN1.

If you disconnect and reconnect from the other RRAS server, RRAS attempts to connect to the next available VPN interface. There is a longer time delay in connecting because RRAS checks VPN2 to determine if the interface is configured for "Dial out and receive calls as a demand dial router." RRAS determines that VPN2 is not configured as a demand dial router and moves on to the next VPN interface.

When the second connection attempt succeeds, the RRAS Administration tool of the example server shows a connection to VPN3.