There are three possible protocol choices for 70-270 Exam 2003 virtual private networks (VPNs)
. Knowing which one to use where is simply a matter of understanding the characteristics and limitations of the protocols, the requirements of the planned remote access connection, and the possible types of VPNs. Thorough knowledge of the protocols and VPN types will assist you in designing secure remote access connectivity.
After this lesson, you will be able to
Explain the purpose of a VPN.
Describe the types of VPNs that work with Windows Server 2003.
Describe the VPN protocol that Windows Server 2003 can use.
Explain the uses of IPSec tunnel mode.
Explain the MCP certification considerations for comparing VPN protocols.
Select a VPN protocol for a specific communication task.
Estimated lesson time: 30 minutes
What Is a VPN?
A virtual private network (VPN) is a way of connecting two networks over a third net-work. VPNs allow us to think of and configure the connection as if it were a connec-tion between two computers on the same network, and they allow us to treat the data as if it were traveling on such a network. This emulation of a point-to-point connection is possible because each packet is encapsulated by adding an additional IP header. It is the information in this header that is used to route the data from one VPN endpoint to the other. Within the packet, the data can be of any type. In fact, a VPN can be used to transport NetBEUI, Internetwork Packet Exchange (IPX), or any other network protocol across a Transmission Control Protocol/Internet Protocol (TCP/IP) network. The encapsulation of the data allows us to treat the communication as if a physical tunnel were created between the two endpoints. Figure 7-1 shows the VPN concept. In the figure, the actual routing path of the free Cisco practice exam questions data is shown by using solid lines. A pipe-like drawing represents the logical tunnel between the two networks.