A demand-dial PPTP (Point-to-Point Tunneling Protocol) connection between two Windows servers that use the RRAS (Routing and Remote Access Service) disconnects every 1 minute and 30 seconds.

If you set Log the maximum amount of information on the Event Logging tab in the RRAS MMC, an event similar to the following is logged in the System event log every time the PPTP tunnel disconnects:

Event Type: Information Event Source: RemoteAccess
Event Category: None
Event ID: 20048
Date: DD/MM/YYYY
Time: HH:MM:SS
User: N/A
Computer: <ServerName>
Description: The user <DomainName\UserName> connected on port VPN4-127 on MM/DD/YYYY at HH:MM and disconnected on MM/DD/YYYY at HH:MM. The user was active for 1 minutes 32 seconds. 749 bytes were sent and 10349 bytes were received. The port speed was 10000000. The reason for disconnecting was user request.

This behavior may occur if the VPN servers have been configured to use two PPTP tunnels, and if the end that initiates that the PPTP control channel is running NAT (Network Address Translation).

NOTE: NAT may be active if it has been configured in RRAS or if the ISA (Internet Security and Acceleration) server Firewall service is started.

Two PPTP tunnels may be established if the user name of the calling server does not match the remote server's demand-dial interface.

When NAT is running on a RRAS VPN server, all outbound connections are subject to NAT.

To alter this behavior, configure the Demand Dial interfaces and user names so the interfaces are associated and only one PPTP tunnel is used. If both ends are running ISA you can use the ISA server VPN wizard, or you can use the following, replacing the names SiteA and SiteB with the location of each site.

On SiteA

  1. Open the RRAS MMC and then expand Server.
  2. Right-click Routing Interfaces and press New Demand-Dial Interface.
  3. Press Next to start the wizard.
  4. In the Interface Name dialog box, use the SiteA_SiteB interface name and press Next.
  5. In the Connection Type dialog box, select Connect using virtual private networking (VPN) and press Next.
  6. In the VPN Type dialog box, select Point To Point Tunneling Protocol (PPTP) and press Next.
  7. In the Destination Address dialog box, type the IP address or the DNS name of the destination VPN server and press Next.
  8. In the Protocols and Security dialog box, leave the default settings and press Next.
  9. In the Dial Out Credentials dialog box, use SiteB_SiteA as the user name, type the domain name and password, and press Next and Finish.
  10. Right-click the newly-created demand-dial interface and press Properties.
  11. On the Options tab, change Connection Type to Persistent Connection and press OK.
  12. Expand IP Routing and press Static Routes.
  13. Right-click Static Routes and New Static Route.
  14. In the Interface list, select the newly-created interface SiteA_SiteB.
  15. In the Destination field, type the network destination for SiteB.
  16. In the Network Mask field, type the subnet mask for SiteB and press OK.

On SiteB

  1. Open the RRAS MMC and expand Server.
  2. Right-click Routing Interfaces and select New Demand-Dial Interface.
  3. Press Next to start the Wizard.
  4. In the Interface Name dialog box, use the SiteB_SiteA interface name, and press Next.
  5. In the Connection Type dialog box, select Connect using virtual private networking (VPN) and press Next.
  6. In the VPN Type dialog box, select Point To Point Tunneling Protocol (PPTP) and press Next.
  7. In the Destination Address dialog box, type the IP address, or the DNS name of the destination VPN server, and press Next.
  8. In the Protocols and Security dialog box, leave the default settings and press Next.
  9. In the Dial Out Credentials dialog box, use SiteA_SiteB as the user name, type the domain name and password, press Next and Finish.
  10. Right-click the newly-created demand-dial interface and press Properties.
  11. On the Options tab, change Connection Type to Demand dial, change Idle time before hanging up to Never, and press OK.
  12. Expand IP Routing and select Static Routes.
  13. Right-click Static Routes and select New Static Route.
  14. In the Interface list, select the newly created interface SiteB_SiteA.
  15. In the Destination field, type the network destination for SiteA.
  16. In the Network Mask field, type the subnet mask for SiteA and press OK.