754 PPTPN0008589 3.3IPSec tunnel modesIn the IPSec Specification, there are two tunnel modes defined: tunnel mode and transport mode.Business Communications Manager supports only tunnel mode. Tunnel mode describes a methodof packetizing TCP/IP traffic to create a virtual tunnel.Tunnels are created between servers, which are also known as gateways. This is called a BranchOffice Connection. The end nodes connect to each other through gateways. These gateways set upthe tunnel over the PDN on behalf of the end nodes. The establishment of the tunnel, and the PDNin between, is transparent to the end nodes which behave as if they are interacting through a router.Typically, the edge devices connecting the branches of a corporation to the ISP use VPN in thismode.Business Communications Manager is compatible with the Contivity Extranet Switch and theShasta 5000.The following sections describe configuring the tunnel portion of Business CommunicationsManager using PPTP or IPSec.PPTPPPTP is a tunneling protocol supported by Nortel Networks, Microsoft, and other vendors. ThePPTP client is available for Windows 95 (www.microsoft.com) and is built-in to Windows 98 andlater. Third-party vendors have developed PPTP clients for Windows 3.1 and the Macintoshoperating system.The PPTP client and PPTP server software are components on Business CommunicationsManager.This section includes information about:• “Settings required for PPTP tunnels” on page 755• “Changing the PPTP settings” on page 756• “Adding a PPTP client” on page 757• “Deleting a PPTP client” on page 758• “Adding a PPTP tunnel” on page 758• “Configuring a PPTP tunnel” on page 759• “Deleting a PPTP tunnel” on page 764• “Encryption” on page 766Note: PPTP uses Remote Access Service (RAS) to establish connections. For this reason,you must do some Dial Up resources configuration when you configure for some of thePPTP configuration parameters.
